The problems using iron liners for bore scoring - Page 5 - Porsche General - PistonHeads UK

I have been commenting for some time about the problems associated with recent practice of fitting steel liners to the M96 and M97 engines (to save a few quid over the cost of quality alloy Nikasil plated liners - that we use) and warned that we have received several fitted with steel liners elsewhere sent here for re-doing with Nikasil alloy liners due to various problems. These include the differential expansion causing them to sink and head gaskets leaking, twisting in the block, and mainly smoking through the need for excessive piston clearances (necessary with steel) and high wear rates. These were the reasons most performance engines dropped this technology several decades ago (including Porsche). There can be a case for fitting them in smaller diameter bores if they are cast into the main block but fitting wet liners in steel as an after market solution has not been used in most applications for ages. It seems to me that it must be a poor solution if after paying elsewhere for them to be rebuilt with steel the same engines soon come to us for a further rebuild - doing the job properly - and as our liners cost only £417 each (if fitted as a batch of 6) or £600 (just for one) the difference in cost compared to steel is relatively small compared to the whole rebuild cost for something that will last forever - but still they keep coming in - so someone somewhere is doing a lot of trade that isn't working. As we also offer to re-round remaining cylinders and fit securing rings to keep them round (that costs much less than steel liners) or fit all 6 alloy Nikasil liners for a permanent solution - I am surprised so many people still fall for this options that costs more in the relatively short term (not even reaching the "long run"). So I wondered if people believed my posts or thought it was just to drum up business - so I asked the engine building technicians if they kept any of the steel liners we removed? Unfortunately most have been thrown away but we did find the most recent ones that I have photographed. These show three basic designs - all of which needed replacing. The block shows the top of some that have sunk as well. Considering the numbers involved - there must also be plenty running around with high oil consumption etc and others that have not been sent to us yet to do properly - so as most of these liners came in as single fits or three on one bank - the pictures prove just how many are failing - be warned. Pictures of the top of a block with a steel liner that has dropped, our alloy liner and a set of cylinder blocks we have not yet removed the liner from and a few different liners recently taken from other engines and replaced with alloy Nikasil alternatives (as Porsche themselves use in the GT3 and Turbo engines). Baz Edited by hartech on Friday 16th August 15:43

you pays your money and takes your chances,rebuilding with steel liners is a false economy but so many things are built like that today. why didn't Porsche fit nikasil in the m96/7 in first place and in the 9A1 block ?I know they are more expensive but surely on a £60k+ car it wouldn't add that much.even my friends tuned lambretta has a nikasil bore and forged piston,he even tried expensive ceramic bores but they too weren't that good either. Edited by itsybitsy on Friday 16th August 16:11

What is the actual difference in price between steel liners and the other?

Hi Barry, We have had an engine reworked by Capricorn and they use steel liners... They bore the complete old liner/cylinder out and install a full liner like the ones you show in the picture with top hat. Have you come across any of these ? Mike

It is an interesting subject - sorry if it comes over as a bit of a lecture explaining the issues - but they are actually not that challenging to understand. Racing engines have less of a problem with differential expansion and clearances because the engines are only ever going to be used flat out and no one is interested in emissions at tickover. Smaller domestic cars have small pistons and low temperature gradients to work with but powerful large sports car engines have quite a problem to overcome. On the one hand they need tight piston clearances at low output (both for emission readings and driving in say town/city situations without high oil consumption or emissions) and tight clearances flat out (to stop the piston faces overheating from too much blow by). The difference in thermal rates between 30 mpg and 160 mph are massive. Iron or steel has an expansion coefficient half to just over half that of aluminium – so does not expand as much. This can cause problems both with trying to keep close piston clearances for low and high speed runs and also for keeping the right surface contact when it is fitted inside an aluminium cylinder block that is expanding at different rates. Similarly iron and steel have thermal conductivity rates about 1/3rd of aluminium – so do not transfer as much heat through them as aluminium does. An iron or steel liner therefore expands at different rates to the piston and also does not dissipate as much heat. In racing engines this heat transfer problem can be compensated for somewhat by the design of the coolant channels (often with holes drilled along the side of the liners to cool them closer to the inside reducing the wall thickness for the heat to transfer across). Similarly the clearances between the piston and cylinder bore can be set larger for the temperatures reached at racing speeds and coolant flow design can compensate somewhat. It is well known by racing engine engineers that one of the most important breakthroughs 4 stroke engine tuners made some decades ago when tuning standard production engines was to alter the coolant flows to equalise cylinder and piston temperatures by changing the flow design often with external pipework High performance road engines suffer from having to perform at very light power outputs (actually for most of their life) while also being able to perform flat out at racing speeds and often actually on race tracks – and this creates difficulties over setting the right piston to cylinder wall clearances for both extremes. Manufacturers have for decades spent millions trying to get away from steel liners in engines as a consequence. Engines with smaller diameter pistons (usually multi cylinder V8 or smaller 4 cylinder engines) have less of a problem that larger capacity engines with fewer cylinders -because the growth in size of the cylinders and pistons is greater in proportion in a larger bore than a smaller cylinder or piston at the same temperature range). Some iron liners that are cast in overcome the expansion differential problem by ribs cast into the liner and aluminium to force the liner to expand at the same rate. This was OK in small bore engines but not so successful in larger bore ones. The early 911’s had steel liners but soon converted to Nikasil plated alloy cylinders (that ran with closer clearances and didn’t wear out as quickly) and the 3 litre 944 S2 and 968 had at the time some of the biggest pistons fitted to similar sports cars and to solve this problem Porsche introduced a wholly alloy cylinder block and pistons with a homogeneous silicon particle mix (Alusil) and that worked brilliantly. When we consider the M96 and M97 engines – they already have a weak open deck cylinder design and an unbalanced coolant flow that results in the thrust face of bank 2 cylinders (where all the problems are) running hotter than on bank 1 (where there are very few problems). As liners cannot be retrospectively cast in the only option is to fit them to a machined cylinder bore. This can be done 2 ways – fit the liner inside the alloy remaining (as most others do) – or completely machine away the upper alloy (where the coolant is) and fit a new solid liner therefore directly in contact with the coolant on one side and the cylinder bore on the other (as we do see photo) – and in the process make it sit inside the outer top diameter converting the cylinder block to a favoured closed deck design. Furthermore you may notice the ribbed exterior which increases the contact area with coolant and increases heat dissipation even further (a great improvement over any other solution). Heat transfer through 2 dissimilar materials is always reduced so even though steel transfers less heat this is exacerbated by connecting it to the alloy before it reaches the actual coolant. Our solution has the new alloy liner directly in contact with the coolant providing something like 4 times the ability to transfer heat away from the piston and combustion chamber. Fitting a steel liner therefore has several disadvantages. (1) The expansion of the alloy gradually reduces the interference fit so that the liner may even become loose (we have seen several rotate in the block) or it reduces the already much poorer heat transfer rates. (2) The top deck height varies between the steel and aluminium and the head gaskets are solid triple layer steel with very little ability to adjust into changes in the sealing face. (3) The wear rates of steel are well known to be poor compared to Nikasil (that is why previously manufacturers made oversized pistons for re-boring) but Porsche did not make any oversized pistons removing that option when they wear. (4) The steel liners that are plated with Nikasil overcome that “wear rate” disadvantage but still have the problem of differential expansion and lower heat transfer and as the main cost is in the machining, rebuild labour costs and Nikasil plating – the minute difference in liner cost between steel and alloy is so small it seems hardly worth putting a recognised inferior product into the rebuild to save a few quid. None of the steel liners we have had back to replace have Nikasil plated bores. Only time will tell if the extra cold clearances they must run with and the higher piston temperatures that must result will reduce longevity compared to an alloy Nikasil solution. This is particularly relevant since the original piston coating applied both to the first Lokasil engines and all the original Alusil engines – is not longer available as a process in the West resulting in even the Gen 2 engines running with a different “plastic” coating to the pistons that the previously successful Alusil 944 and 968 engines - and time will also tell if this is as good (which I have my doubts about). It is no coincidence that Porsche themselves fit alloy Nikasil plated liners to their GT3 and Turbo engines and have reverted away from Lokasil to Alusil for their Gen 2 engines – nor that these engines have excellent longevity. As we are expanding our engine rebuild facilities (now including CNC machining of the blocks) we have been reducing our prices as production efficiency increases (and this also allows us to machine a better coolant flow rate for the cylinders – all thrown into the job FOC). I don’t know what the prices are for fitting steel liners and Nikasil plated steel liners (perhaps others could post that information) because I am frankly not interested in building an inferior engine and have such a huge success rate building far more engines than anyone else – any extra cost speaks for itself – in my opinion. However there are always those that will want a rebuild at the lowest possible cost regardless of how short a time it works successfully and these will also be liable not to change other things to help the engines survive the longest – probably not a low temperature thermostat (that we pioneered), supported cylinder bores, etc etc. Regardless of any other arguments others may like to raise or promote - It is clear from the number of engines we have had to rebuild to replace steel liners that for many it has not worked out for very long at all and was a false economy. I am just trying to point out these issues and demonstrate that they a real and active problems. I have no axe to grind about anyone preferring steel liners and although steel liners with Nikasil plating may be OK for wear rates – they must still run with bigger cold and low speed running clearances than you can achieve with an alloy Nikasil plated liner. They may also be OK in engines designed for them with appropriate cooling changes and piston materials and especially for narrower applications. We are trying our best to match prices with these to encourage customers to make the right choices technically in their own best interests. We are not stopping others offering similar alloy liners – so are not just promoting our own product – we are genuinely trying to make sure customers do not get led by the nose to a solution that possibly increases the supplying businesses profits or saves them a small amount if the short term only to cost more in the long run. We fit these alloy Nikasil liners for many other independent businesses and are even setting up to do so Worldwide – because we believe in the quality of this solution and understand the short comings of many of the alternatives on the market. For those struggling to afford such a repair we offer another alternative that is actually less expensive than three steel liners – just replacing the scored bore with an alloy Nikasil liner and then re-rounding the remaining good Lokasil cylinders (converting them to a closed deck in the process) and increasing the coolant flow there while fitting a low temperature thermostat – that is working out very wel and reliably – but it is not as good a fitting three or all six alloy Nikasil liners which we have heavily discounted to encourage uptake. Compared to the cost of a replacement new engine (with the same faults that caused the original to fail) even one rebuilt with 6 Nikasil liners can be half the price and includes lots of other technical benefits. We predicted the continual growth of failed engine numbers and really cannot cope with anymore than we presently handle – so this issue is not in any way to “drum up business” it is just that as an engineer that first was involved in the manufacture of Nikasil plated alloy cylinders over 40 years ago (with two stroke racing motorcycles) I happen to coincidentally know a lot more about the subject than most other specialists and this is the only proper solution. I am putting the technical arguments forward to counter those talked into a less satisfactory solution by engineers that either don’t know any better or are trying to get the business on the back of potentially a little less cost and don’t care about the long term consequences for the customer. Our solution may be a little more expensive but we are trying to subsidise that as much as possible with more efficient production methods and quantity price reductions – and I don’t think there is much (if anything) in it any more. If things continue as planned we will one day be able to invest in an automatic multi tool change CNC machine and then we may even be able to beat the prices for inferior steel liner fitting – giving customers the best of both Worlds. Arguments about what other manufacturers or racing cars do are irrelevant because the whole design is different and often so is the application. There are not many road cars that can also reach 160mph or more and it is this technical problem that encouraged Porsche (and others) to find solutions that involved alloy cylinders. They seemed to go a little bit wrong with the Lokasil solution – but that hasn’t changed the principle – nor the best solution. It seems that at some time in the near future most engines will have alloy blocks with plasma coated cylinder bores and this may well be the final solution but we have had to deal with an existing problem with an engine with other short comings and fitting steel liners into that already flawed scenario is in my view asking for trouble and the engines coming here to replace steel liners – seems to me – to confirm that totally. Meanwhile I do not believe that the difference in our alloy liner prices is significant compared to the whole cost of the job and not enough to risk the obvious consequences. Baz

One other way to look at the problem is that a small engine'd car (sat 1 or 0.4 litre) travelling at say 40mph is working its small pistons quite hard and they are quite hot and have already expanded quite a lot compared to fully expanded flat out at say 100 mph. A big 3.6 litre 6 cylinder engine has piston area many time greater and a longer stroke and so the pressure force on each piston @ 40mph is very much less because it multiplies by the area of the top of the bigger piston (and all 6 of them) - so the temperature of the burning fuel is much lower and the area of the larger piston to dissipate that heat through the much larger cylinder walls is also much greater. This means the pistons in a larger engine @40mph will not have expanded as much (as a proportion of the full power expansion) as the much smaller engine at the same speed. However when the big engine is flat out - the output needed to propel a car @ say 160mph compared to 100mph for the smaller engine is much higher and as the pistons are bigger the difference in the size of the small and large pitons between running at 40mph and flat out is much greater for the bigger engine. So piston clearances become more of an issue for the bigger engine. This is why different solutions reach a technical limit of their suitability sooner with bigger more powerful sports car and why the introduction of all alloy blocks and cylinders became a solution to this difference in expansion rates managing to keep the piston clearances much closer at all levels of power than is mecessary with smaller engines and steel liners. Baz

..Baz, Interesting reading here, I use to be involved with race engine development myself for TWR where we had considerable success on the track from group C to BTTC, and many others too. I've seen (and measured) more bores/liners/pistons than I care to remember, and the different materials coefficients of expansion is something that you can never get away from it's always a compromise in mixed metal solutions. Most OEM blocks I saw came in with cast iron liners pre-cast into alloy blocks, some race engines we would bore them out and fit machined cast iron liners into, I think we tried just about every variant on coated liners too, Nikasil was a frequently used one, some chromed bores too. The problems I saw with the coated bores were that after honing there was often a lot of pitting in the surface, you can't see this until the bores are sized as the cavities are hidden in the coating until it's honed, it was often a reason why I sent liners back, I don't know how many rejects you get, maybe the process is a lot better now. The step height from location surface to gasket face tolerance was 20 microns and these were always hand selected to get uniform critical deck heights, are you using a stock head gasket or using machined rebates for Cooper rings or similar in your liners ..? What is the thermal expansion rate for the Nikasil compared to your parent alloy liner..?, I've seen examples of flaking here too when the coating comes away, gets picked up and makes a big mess very shortly afterwards, so this solution does have potential downsides, compared to say a cast liner which is all the same material. Are you using stock OEM rings..? On a subnote, it still makes me chuckle that most people think pistons are round.. Edited by RatBoy M3CSL on Sunday 18th August 12:48

Yes that's all correct Ratboy but of course all your work was it seems with racing engines and as I already explained that is not a problem because you only ever run at one temperature area and can apply clearances to suit. It seems difficult to get over the reason why a road sports car with large capacity has a much greater problem over the range of pistons sizes it experiences during different uses - perhaps it needs reading again. We have no problems with flaking nor pitting and the Nikasil is now recognised as the perfect solution (until the next one comes along I guess). Porsche thought it was Lokasil but it wasn't. Nikasil is so well bonded in the liner it moves with it no problem there the only problem is if it ever badly overheats when it can come away but the engine would be finished by then any way. The key to understanding this issue is to recognise that a large capacity road car piston goes through bigger size changes than a smaller one and therefore if you have a liner that doe not expand as much as alloy - you simply have to start out with greater clearances - even though this is the speed range the engine spends most of its life covering. Baz

..Interesting to know you have worked thro' your own solution, made the parts and have bought them to market. My 996 engine hasn't let go so far, seems to run cool and doesn't use any oil, but if it does I will come and see you..! The principle of 'the bigger it is the more it expands' still stands and you can run out of clearance quickly thro' a temp range as you point out. What bore distortion are you getting after assembly torque is applied..? if any ..? We used to use a dummy honing plate, torque it up to assembly figures then hone the bores. Take the plate off and they were not round any more, but on assembly they came back in very close. All the best. Edited by RatBoy M3CSL on Sunday 18th August 18:37

We do not suffer any distortion but how is our secret - sorry! What a lot of people don't realise is that Porsche found a way to overcome this variation in piston and cylinder expansion for a large engine'd road sports car and the huge range of temperatures and size changes the piston would go thought) when they changed from an iron block with the 924 to an Alusil one for the 944 and the result was an outstanding car. It was a brilliant piece of engineering that would not have worked had they not also followed the lead from the USA in pioneering ferrous coated pistons to survive in the Alusil bores. They managed to push those boundaries to a 3 litre version with 104mm pistons with the S2 and 968 versions but if they had done this with steel liners they would have encountered the very problems I have been discussing - it would not have worked out like it did with 944 and 968 engines having covered 200K or so still running great. Alusil proved to be so good some even ran for quite high mileages with a new type of "plastic" piston coating. But Alusil has silicon in the whole block and is hard to machine and expensive to produce as a result (but extremely strong and more stable than commercial cast aluminium). They also succeeded in increasing the piston sizes with the 3.6 and then 3.8 996 and 997 but two very significant changes were made that have caused these problems. (1) They change to Lokasil (which needs a ferrous piston coating - or something new yet to be identified - to survive) and Lokasil is less stable and less strong as is the aluminium they cast around it - resulting in the very migration to oval we speak about in the thrust direction. Running the engines at a higher temperature (to assist with emission control) didn't help the plastic coated piston material to last as long as it could have done if run cooler either. (2) It seems they were unable or unwilling to use the original piston ferrous coating (I undertstand due to environmental health and safety limitations to the process). They have now returned to Alusil in the Gen 2 engines but still are not using the original ferrous coated pistons that worked so well in Alusil in the 944 and 968. However they seem to have found a suitable new piston coating The early M96 2.5 to 4.3 engines still used the ferrous coating with pistons supplied first by the block manufacturer (KS) and at the end by Mahle who then supplied pistons with a plastic coating. This combination in block 2 is the problem side (because the thrust face runs hotter and platics don't like excessive heat). Nikasil (as I am sure you already know) provides such a good long life wear resistant coating that it can run with pistons with almost any coating or no coating at all - unfortunately it is relatively expensive - but so much so that they use it in the GT3 and turbo engines - because they know their stuff and can charge more for the end product to cover the extra costs. Two cylinders inside each other never work as well, are as stable with temperature changes or transfer heat as well as one homogeneous material and we use a very high strength alloy and replace the whole original Lokasil and alloy block material so our new liner is totally in contact with the coolant. I am extremely frustrated that the vast majority of people and specialists simply don't understand these issues or the significance of them and many are resorting to a solution that is never going to be as good or as reliable as ours - especially when the owners who chose steel have to get the engines done for a second time. I wish I had the ability to explain this phenomenon better so everyone "got it". You would think the facts speak for themselves but unfortunately it seems they do not even for people with the engineering experience to know better. I guess there is a limit therefore to what I can do to convince them and anyway we could not handle many more engine repairs than we do now without some major expansion and investment that is not currently planned. It really is simple - if you want to use steel or iron there is a limit to how big the pistons can be to cover the whole range of temperatures they go through in a road car in road use. Hence if you want a bigger capacity with steel or iron liners you have to have more cylinders. Porsche found a way to have large capacity engines with fewer cylinders thanks to this new alloy cylinder technology (and balance shafts) - but the change to Lokasil in the 6 cylinder engines just didn't work out for enough cars once the original piston ferrous coatings were replaced by plastic ones. By lowering the cylinder temperatures and re-rounding the oval Lokasil cylinders - we have found a way to reduce the problem so in most instances they work OK with the original Lokasil - but a much better solution is obviously to replace them all with Nikasil - so we offer both solutions - one less expensive anyway than steel and so far working out very well indeed and the other the best you could possibly get with current technology. The practice of using steel (even if it is Nikasil plated which we have not yet seen) is IMHO a flawed solution introduced to either save a small amount of money or increase the profit for those applying it on their customers behalf. It is a typical cheap solution and the usual consequences will follow. The additional cost of ally Nikasil liners is a small additional price to pay for the best solution yet to be found or applied to engines with such large pistons and already proven by Porsche in their other trouble free models. However in our research and development we have engines running around with LOkasil bores and new piston coatings - some of which have never been tried before (one of which looks very encouraging) but we should really not be trying to carry out such expensive and time consuming work form such a small business - and it is a huge financial and labour intensive task and unfortunately takes thousands of test miles and engines strips to asses - but we are trying. It should have been undertaken by the manufacturers but if someone like us didn't - it would be new engines for everyone at usually more than twice the price and with the same flawed technology. Meanwhile we offer the best solution and are continually trying to bring the Nikasil cost down to match steel - and to find a new psiton coating that lasts well in Lokasil - to encourage even the most impecunious owners to choose the best solution for their rebuilds. Baz

Are we referring to these things? http://www.westwoodcylinderliners.co.uk/products/b...

Hi Sump, We do not name competitors products and never have - life is difficult enough on the internet and people have different opinions and experiences - so we feel that is unfair to do so (and anyway the value of our contribution would be diminished by those assuming it was pure self promotion) so we always only refer to either our own products or purely technical considerations (as in this case). Again the issue is not which steel/iron liner is used or who made or fitted it but a broader issue about the ability of pistons in large bore engines being able to fit into the bore with the correct clearances for very slow and very fast speeds the engines are capable of. Try and imagine the amount of combustion pressure the engine has to create to push 6 relatively big pistons along so the car travels at say 30 to 40 mph (which if you refer to the hours running records and mileages covered is about the norm). That pressure pushes on the whole area of the piston creating a downward force - so the larger the piston the less the pressure has to be to be above it to achieve the same force (and the difference increases with the square of the diameter). So big pistons running at modest power outputs are really relatively cool and have not expanded much. However the force neccessary to push a car along against air resistance at say 160mph is huge and once again is a factor of the square of the speed (or even more) greater than at a slower speed - so a car that will only do 100 mph needs a lot less force to get there than one capable of 160mph. Making an engine that will run with the right clearances for both scenarios is therefore easier as the piston diameter is smaller and the top speed lower - so is the biggest problem technically for an engine with big pistons capable of 160 mph - like these engines. Large pistons (and therefore less cylinders) means fewer parts to make (less cost) and less internal engine resistance at low revs/speed so makes a fuel and emission efficient engine - so is desirable. The problem however in designing such an engine is in keeping the piston to cylinder bore clearances right for such very different thermal conditions (between the maximum potential top speed with can be up to say 60% different in different cars - and the minimum speed most cars drive around at all day long - which is much the same)and using materials with dissimilar expansion rates makes it a lot more difficult - especially in engines with accepted problems over unbalanced and reduced cylinder coolant flow. That is why, many years ago, manufacturers tried lots of different ways to find pistons and coatings and cylinder finishes that would allow the cylinders to be made of materials with more similar expansion rates to the pistons - something that the practice of fitting steel/iron liners goes completely against for this type of applications. Bearing in mind that there must be relatively few engines out there fitted with these liners, that it has only been a recent phenomenon and how much extra someone must be paying to remove and replace them so soon after rebuilding them - I am amazed and concerned about the numbers that we are getting through here and can only conclude that since there is such strong technical and historical evidence against their suitability and such high practical "real World" evidence at their failings - that it is not the best solution and as such I hope that explaining all this enables some owners or businesses to justify the better solution - for the sake of all involved. Although we do use the better alloy Nikasil plated liners - please remember there is nothing to stop our competitors doing the same and in the same way that several have copied things (like our IMS solutions etc) - this technical warning is not about our product promotion but is a real absolute technical issue that we have got right - that others could follow - but that they seem not to do - for reasons no one yet has tried to defend (for rather obvious reasons). Baz

.Thanks Baz, I'm sensing your frustration, but over time now you have a reliable fix, the best advertising for your product is always going to be durability in the field and customer referrals. Thanks for typing your journey up to get here, a wet liner has better heat transfer properties, but requires some extra machining to make a space for it, and they do need to have thicker walls than a steel to withstand the cylinder pressures. Similarly making a round bore @ 20C is 1 thing, but keeping it round after it's torqued up and running hot is another thing altogether..! I was head of the dept @ TWR responsible for measuring the results of all the variations of materials / coatings / processes used and resulting shapes achieved, and I know it was a long journey even with the resources and equipment we had back then to do it. Interestingly we tried low friction piston coatings too, Xylan it was called and a green very slippery plastic, ultimately it wears off tho'. We did a few road car engines too, notably the XJ220, and the prototype DB7 straight 6 supercharged one which I remember well, as we had some piston slap to figure out and the resulting rattle was not a good sound on the early engines..! Edited by RatBoy M3CSL on Monday 19th August 10:05

That's very interesting Ratty and we too have tried Xylan (in green and orange - don't think that makes any difference) and the problem with the Lokasil is interesting - and I think you will be interested so I will explain it further - just for your benefit. When the silicon was mixed in with the aluminium and cast in everywhere (as with Alusil) - it resulted in a very strong but difficult to machine block that was extremely stable. It had an open deck design but was so strong it only ever went oval and cracked if used in turbo applications at very high boost pressures and then only after a lot of use. The Lokasil solution was thought to end up the same and was advertised and promoted technically as just the same. It was made from a preform cylinder that was explained as a porous moulding entrapping silicon in a porous matrix. This was then fitted into the metal moulds and molten aluminium was applied under pressure. The result was that the molten aluminium flowed into the porous spaces and burned off the original bonding agent leaving the silicon suspended in the aluminium in exactly the same way it was in Alusil. It was therefore claimed to be just the same but of course only entrapped the silicon content at the surface where it was needed hence it was called "localised silicon" or lokasil. The block material was not as strong as the original Alusil and the Lokasil preform was even weaker than either - so the combination of the two resulted in a relatively weak and unstable open deck cylinder and no wonder it soon goes oval and eventually cracks. This could have been improved if Porsche had increased the diameter of the outer alloy (but they reduced it instead) or secured the tops with a ring (but they didn't). In reality the silicon particles in Lokasil are not IMHO as well secured in place as they are when mixed in with molten aluminium in the Alusil solution. I also do not expect the distribution to be as even nor the individual particle bonding to be as good. They also changed the sizes and concentration of the silicon from Lokasil 1 to Lokasil 2 but I cannot find out any more about why or when. I also cannot find out what the particle size is and the concentration % in the original Alusil - but it stands to reason that to make a porous preform there may not be as many particles - but that is just conjecture on my part. Because the whole situation went pear shaped it is very difficult to find out as much as I would like. I did obtain a lot of help direct with the original engineers at KS but since things have gone worse and more in the public domain - that source has dried up! What I do know is that the distribution of the silicon in Lokasil is not as even in the resulting cylinders and the positioning of the preform is not always perfectly central. I think the particles are not as securely fixed in the matrix as they are in Alusil giving rise to a random number falling out and this exposes new sharper particles to score the plastic coated pitons. After boring and honing the Lokasil with diamond cutters it is necessary to expose the silicon particles with a special material and this also reduces the sharpness of the edges of the silicon particles - but of course if they then fall out they expose new particles that have not been similarly treated. We have the surface measuring equipment to check all this and the manufacturing equipment to carry out the reboring, honing and exposing of the Lokasil to do this (and had the quality of the end result confirmed by KS as correct) but so far have failed to obtain a piston with a coating that will survive long enough. For sure an aluminium piston will not survive in a Lokasil bore without a coating of some kind. The Mahle pistons have a screen printed material called Feroprint - but unlike the original Ferrous coated pistons they are not magnetic (as the ferrous coated ones were) so I am not sure what the coating material actually is (or where the ferrite is) - but I am sure it can flake off and rub off over time - resulting in a problem. In contrast Nikasil will run with anything. It is interesting that another specialist worked out that the earlier cast pistons were better than the later forged ones (and thought this was the explanation) but missed the fact that it was the change in coating that coincided with the change in pistons supplier and it was the coating that was the relevant issue not the method of production. As I said before - this level of research should not need to be undertaken by such small businesses as ours when such a large manufacturer gets things wrong and tries to wriggle out of responsibility by putting up smoke screens. Like all plastics - temperature is important for the key to the piston surface and the unbalanced coolant flow results in bank two pistons running hotter on the side that scores than bank 1, so temperature comes into the problem (hence our increasing coolant flow through the block and fitting a lower temperature thermostat). The new coatings we are testing will remain our secret for now but this has been part of a long term plan to enable us to overbore the Lokasil and provide oversized pistons. It has cost us a small fortune but will pay off for us and our customers if we can find something durable enough. Meanwhile the Nikasil solution works brilliantly - it is just more expensive than reboring the original Lokasil and fitting the alloy rings to the top to comvert the engine to a closed deck and prevent them going oval. To help reduce this cost we have automated the machining out of the original block but until we can afford to invest in an auto tool changing CNC the result of the added cost of the Nikasil plating still makes us a little more expensive than steel or iron (although I believe our trade price is the same anyway). There is very much more that we have researched and tested that I could explain but from your position I think you will already know from these responses that we are extremely competent at what we do and have carried out more research and development in a proper professional manner than you would expect inside our Independent Porsche sector - and basically - that we know what we are talking about. It is a shame for those who are persuaded to resort to steel or iron (for possibly a very small saving) that they do not appreciate these issues in the same way you probably do! If they did I cannot imagine anyone going that route. Baz

Thanks RatBoy - so nice to communicate with someone that knows their onions! You are very welcome here any time. Baz

Baz, Would it be possible to fit a nikasil plated Alusil/alloy dry liner to a 944 104mm block ?. Edited by blade7 on Monday 19th August 16:59

RatBoy M3CSL said: .someone who will remain nameless wheeled a complete RC45 Honda GP bike into my office and said have a look at that engine and see what we're doing wrong will you.. ! Calling a superbike a GP bike probably...

blade7 said: RatBoy M3CSL said: .someone who will remain nameless wheeled a complete RC45 Honda GP bike into my office and said have a look at that engine and see what we're doing wrong will you.. ! Calling a superbike a GP bike probably... A lot of chat going on here, but not knowing the difference between a Honda GP bike and a world superbike/ road bike? Utter shocking behaviour. What's even worse, back in the day of the RC45 it was a 4 stroke, the then GP bikes were 2 strokes. I'm only a woodworker, its all castrol R to me. :-)

What diameter bore was it? Baz

Yes it is possible to machine the block to not only accept an alloy Nikasil liner bit also have a top hat design locating in machining recesses in the top as well. Our unfinished 3 litre turbo engine is just that - a 994 block machined out for liners already finished @ 104mm diameter, pistons to suit and made to fit to a 16 valve 968 head. We chose the 944 block because it has nearly twice the coolant channel depth and allowed us to redirect the coolant into 2 separate flows (through the 2 block inlets from the coolant pump - the 968 has only one) each dividing the coolant to the front 2 or rear 2 cylinders and out from the front and the rear original heater outlet. Sadly although I am going to try and find time to finish the engine this winter - we will never now find time to build it into the car it was originally intended for - time has moved on and our racing has taken over - but it was planned to suit well over 500 bhp. Baz

Baz - whats your view of the 997.1 CSR that RPM have been in the press with? Is their engine conversion ok?

..Thanks Baz, I can see I will have to come and have a chat with you 1 day..! I've worked extensively with Nikasil coated liners, steel/chrome plated ones, the cast iron liners we machined ourselves from centrifugally spun castings, which were about 90% scrap by weight by the time we had cut the finished liner out in several stages...!, The solid billets are expensive for openers to get the shape as they are 1 piece, you will know this as you are paying for your billets..! Most of our pistons were Mahle or Cosworth, sometimes Accralite or CP. I was head of quality for Pankl a few years after TWR too, who know a little about making nice con-rods..! They took over an American company later and make cranks/pistons too now I believe. Always been interested in the Porsche Alusil/Lokasil solutions, but never had the chance to get too close to the oppositions oily bits when we were in group 'C', or other racing, except the time someone who will remain nameless wheeled a complete RC45 Honda GP bike into my office and said have a look at that engine and see what we're doing wrong will you.. !, I really enjoyed the BTCC program for Volvo too, which we won, that 5 cylinder 2.0 litre on the dyno flat chat sounded lovely @ 8250rpm, we had a great battle with Cosworth as their 2.0 V6 wasn't as powerful and they didn't like it much..! Good to talk to a guy who knows his Ra from his Rz, and what plateau honing is, good luck with your repair package sales moving forward after all your time invested in a fix, as the batch sizes go up the profitability will come back .. Edited for clarity.. as pointed out, it was a '94 GP bike and defo a 2 stroke, not the RC45..! Edited by RatBoy M3CSL on Tuesday 20th August 09:38

csmith319 said: Baz - whats your view of the 997.1 CSR that RPM have been in the press with? Is their engine conversion ok? Not sure that's a question to far for Baz, I have to say it's very good of him to spend time that he has on this thread given that he should be doing other things, so good on you Baz. Some could say it's in his companies best interest to promote his idea's but I'm sure we all know he's better than that, not that I'd know him if I tripped over him in the street!

hartech said: Yes it is possible to machine the block to not only accept an alloy Nikasil liner bit also have a top hat design locating in machining recesses in the top as well. Our unfinished 3 litre turbo engine is just that - a 994 block machined out for liners already finished @ 104mm diameter, pistons to suit and made to fit to a 16 valve 968 head. We chose the 944 block because it has nearly twice the coolant channel depth and allowed us to redirect the coolant into 2 separate flows (through the 2 block inlets from the coolant pump - the 968 has only one) each dividing the coolant to the front 2 or rear 2 cylinders and out from the front and the rear original heater outlet. Sadly although I am going to try and find time to finish the engine this winter - we will never now find time to build it into the car it was originally intended for - time has moved on and our racing has taken over - but it was planned to suit well over 500 bhp. Baz Thanks Baz, If the 2.7 block I have wont clean up at .5 oversize a plated alloy dry liner seems the best option for expansion and heat transfer reasons. I think iron liners can stay put but the fitting process isn't as straight forward as most shops think. I'm surprised someone hasn't snapped up your 944 block/pistons, I would have been interested but I'm using a 8v 2.7 head. Paul.

Tony 1234 said: Not sure that's a question to far for Baz, I have to say it's very good of him to spend time that he has on this thread given that he should be doing other things, so good on you Baz. Some could say it's in his companies best interest to promote his idea's but I'm sure we all know he's better than that, not that I'd know him if I tripped over him in the street! Sorry, should have been more specific! I believe their conversion uses iron or steel liners, so thats what I was asking about. It might not be appropriate, but wondered if he had any insight from his perspective on whether that was a good long term conversion or not as I'm considering the engine modes for mine.

anonymous said: [redacted] I would just like to make a couple of points. We do not make liners out of Steel, never have and never will. All our liners are either made from Spun Cast Iron or Ductile iron.

Baz, Are you using barrel shaped rings to prevent the dislodging of the silicon particles from the alusil walls? I remember reading some stuff on alusil and nikasil way back that suggested it was the solution along with an appropriate coating. Edit to put up links. http://www.aera.org/ep/downloads/ep4/EP10-2008_18.... http://www.aera.org/ep/downloads/ep2/EP04-2008_20-... Nice easy info if folks are interested in the differences in the two after reading earlier posts. Its from 2008 so hopefully there's been more learned since but gives good additional info nonetheless. Edited by fioran0 on Tuesday 20th August 17:08

anonymous said: [redacted] Wow, now that is interesting. Looks like this is another scare mongering thread

fioran0 said: Baz, Are you using barrel shaped rings to prevent the dislodging of the silicon particles from the alusil walls? I remember reading some stuff on alusil and nikasil way back that suggested it was the solution along with an appropriate coating. Edit to put up links. http://www.aera.org/ep/downloads/ep4/EP10-2008_18.... http://www.aera.org/ep/downloads/ep2/EP04-2008_20-... Nice easy info if folks are interested in the differences in the two after reading earlier posts. Its from 2008 so hopefully there's been more learned since but gives good additional info nonetheless. Edited by fioran0 on Tuesday 20th August 17:08 Interesting reading fioran0, enjoyed those... it's the engineer in me, can't help it you see..!

You will see from the title of the original post that we refer almost exclusively to iron liners but the difficulty with the Internet is that you are presenting information for readers at all levels and trying to present the information at a level that can be understood by non engineers and equally for specialists to realise you know more and what you are talking about - is very hard in one post. Others around the World seem to understand them as steel liners so to avoid confusion I have often referred to them as that but clarified it is steel or iron - the consequences are similar except that steel needs a coating and iron does not. The stuff about the Vega engine and geenral technical information has been around for ages and is interesting to many (thanks fioran0). We have researched all this to a much deeper level and with direct communications with KS, Mahle etc but I neither have time nor would it be at a level for most readers to follow if I tried to reproduce it all here. Hopefully it does show how Lokasil got paired with (and was implied was the same) Alusil early on - and we invested in the reboring solution and oversized pistons early on as a result but so far the material has turned out to be too different. However - to get back to the point - this is about using iron or steel liners as a solution to bore scoring in M96 and M97 engines and the real problems it seems to have created. I could just have pointed out the numbers we get to re-do - but I took the trouble to explain in great detail (and hopefully at about the right level) some real technical reasons for those failures in this engine. Where is the corresponding technical arguments that all that was wrong? I appreciate iron liners work well in many applications and I am not naming anyone or any supplier in my general comments and technical explanations. I have explained why I do not think they work well in this application and the evidence from people who have tried some of them and had to replace them supports all the technical arguments as well and the evidence from Porsche themselves. Throwing in some other model and manufacturer in which it worked is not relevant since this is about fitting them to Porsche M96 and M97 engines. How they are fitted, the coolant design, the piston coatings and shapes, the ring design etc all may make one engine OK with iron liners and another not. It is a typical and unhelpful cop out to refer to all this as scare mongering (from sources that seem to often set-up against my posts but never offer any constructive alternative technical arguments just tabloid sensational journalism with no content). Anything that tells the truth about a problem can also be referred to in the same way but does not make it untrue. You could put children cleaning their teeth or immunisation into the same pot - it may be scaring to realise the consequences of making the wrong choices but better the public understand the issues and alternatives than live in ignorance. Informing them about the options does not force anyone to choose anything at all whereas not informing them leaves them in ignorance and more likely to make a mistake. The evidence of making a wrong choice is in the outcome and it is here I concentrated on our evidence here at work replacing iron liners chosen by others with alloy Nikasil plated ones. At least in this scenario the mistakes can be rectified if customers want to (unlike losing your teeth or suffering from serious illnesses) you just end up poorer. If it is regarded as scare mongering to explain in detail the truth about a situation and provide evidence of it - set against the total lack of any alternative support from the opposite opinion (either evidential or technical) - then perhaps I am guilty - but I am glad I was informed about other issues in life and am pleased I had all the evidence before I made my decisions. It seems to me that others that approved the fitting of iron liners and then had to have them replaced (at a much greater overall cost) must have been steered towards that original choice without being in full possession of all the facts and all I am doing is providing solid technical and practical proof that there is another side to the story (and I think an overwhelmingly and blindingly obvious one). There is nothing wrong with the quality of the material of the liners we have replaced and I know the suppliers often provide good solutions for others and have no wish to damage their businesses (and some are clearly better than others) - but in this particular case I think the cost difference to do it in a way that has proven better, has been largely adopted by the manufacturer in other models and the sports car World at large in similar circumstances is so negligible (if at all) that I think we have a duty to at least present the information we have on the subject to allow others to make informed decisions. By discussing this readers can make their own choices (and now realise there is a choice) and businesses wanting to save a few quid even though they may have customers come back complaining later - can make that choice if they want to. I don't see what the success of fitting iron liners to other models has to do with this argument - this engine is an odd one on its own with known problems and the manufacturers clearly did not get it completely right and the Lokasil design, unbalanced coolant flow, lightweight short pistons (designed for an aluminium expansion rate not iron) etc etc all make the ideal solution an alloy Nikasil liner. I am perfectly happy to defend this post at any level except histrionic over reaction and easy political points scoring - that sounds good but actually offers nothing constructive to the situation. You must also remember it took several years before the problems emerged (as wear took place to cylinder bores and piston coatings), it has taken years to research and discuss with the original manufacturers, make test components, build test engines, put thousands of miles on them and finally develop reliable solutions. Iron liners have been an easy and quick fix in many similar circumstances and there is a good place for them and their suppliers in the wider market but also very good technical reasons why they are not the best solution in this case. This does not prevent them being a solution but the speed with which some of them are proving unsuitable has surprised us and suggests there will be more pain for those adopting this answer. I think that if the cost of the better solution was hugely more you could understand some people taking a risk but the difference is too small to justify that risk against the evidence we see and remember that whereas Nikasil plated alloy liners have a proven track record for lasting for many years and thousands of miles - whereas even iron done properly has always been associated with re-bores and oversized pistons (that are not available and anyway would cost a small fortune stripping and rebuilding the engine every time) because unlike a lot of engines the whole lot needs to be taken apart to fit a liner or rebore it one day. I think that is about my lot on this subject - make your own choices and don't say you were not warned if and when you find out it was the wrong one. Baz

Baz, Thanks for posting up some genuinely interesting technical information. However, it has put me off a 996 - until I can afford one with the engine sorted!

That's a great shame and they are brilliant cars and what's more prices reflect their weaknesses and not many suffer - but there are an increasing number of cars suitably repaired that are beginning to fetch a premium. Baz

Ive just been reading this thread and one thing from one of the earlier posts about the bmw m52 engine with it steel liners is that they usually use quite a bit of oil especailly either when stuck in traffic or long motorway use ,the 2 extremes of its useage also since I own a porsche 944 s2 and that has scored bores (I also bought a spare engine a while ago cheap off ebay and when I tore that down it also had scored bores ) this is not a new phenomenon and If theyve started using alusil again in alot of applications then pherhaps more companies will spring up or diverse into repairing this blocks and making it cheaper

hartech said: Sadly although I am going to try and find time to finish the engine this winter - we will never now find time to build it into the car it was originally intended for - time has moved on and our racing has taken over - but it was planned to suit well over 500 bhp. Baz I've got the perfect 944 turbo for it to go into

If you are interested E-mail me directly. Baz

yes I also have a nice 944 with a broken engine ! shame you just cant buy a re-coned block

The pistons are the problem, after you have bored/honed the block. The material needs a specialist to complete the work, but when its done you still need to find oversized replacement pistons...

Wossner supply the coated pistons or Mahle if you look hard enough.

Are they still available? What about a Turbo application? Id heard that pistons were no longer available (having not been available from the 944s inception until a few years ago).

blade7 said: Wossner supply the coated pistons or Mahle if you look hard enough. I would not touch them with a barge pole. There is a very nice picture on Rennlist, posted by a very well respected German race engine builder, of a Woessner piston after the coating wore off in a 928 alusil block... I can also show you 8 very chintzy JE Pistons with fancy coating, which failed after 6hrs in my fancy 928 race engine. Precision Motorwerks in CA have forgotten more about alusil than we would ever know - they also say that nothing works in the bore as well as the OEM pistons... Or go Nikasil liners... I am personally going with uncoated JE Pistons in a Darton sleeved block for my 928 race engine... If the liners are good enough to go into an BMW S62 engine, they are good enough for my M49.50 based lump

you can have the bores plated on a 944 block with nikasil and honed back to 104mm reuse the pistons as long as the ferrous coating is removed and have 'exotic rings' apparently ,capricorn have done this for a few years now ,I spoke to one of there sales team the other day ,they come highly recomended and arnt as expensive as the alusil process and new pistons or as you might think ,theyre in basingstoke though so it would be an expensive postage accross the country for my block ,shame hartech dont do this ,they seem to have geared there buisness on 911's and boxsters these days

Were they previously called True Bore or something similar?

Perfect Bore ISTR Simon. They did all the swanky replacement cylinders that John Mitchell / Simon Peckham used in those special 3 litre turbo engines. There also in Andover rather than Basingstoke. http://www.pbm-ltd.com/about-us/history/

GC8 said: Are they still available? What about a Turbo application? Id heard that pistons were no longer available (having not been available from the 944s inception until a few years ago). A Mahle dealer said they knew what I was asking for and they could supply me but I haven't taken it further yet. I have the guts of a 3.0 engine but not the motivation at the moment to pull out and swap a 2.5 that's running well.

Can anyone explain the dangers of getting the liner hieghts wrong on a 6 cyl diesel truck engine.

My 2005 997 is showing the classic signs that it will need an engine rebuild in the not too distant future. I am aware from being a forum member that Hartech are the "Go to" company to get an engine like mine rebuilt and I have no issue with that. However I have a question to ask that I would really be interested to hear peoples opinions on, are we saying that the only place that can be relied on to re build a 997 engine properly is Hartech? The question isn't meant as any slight to Hartech but the UK has many excellent Porsche specialists, surely there are alternatives that people have actually used and been happy with.

I'd take it to Autofarm purely on the principle that Hartech comes and intervenes in every thread scaring people and plugging his business.

Sump said: I'd take it to Autofarm purely on the principle that Hartech comes and intervenes in every thread scaring people and plugging his business. Unfair. Hartech will often give advice free of charge, they have extensive knowledge and are very helpful..if they plug their business a bit too, does it really matter?

colnagoglyn said: My 2005 997 is showing the classic signs that it will need an engine rebuild in the not too distant future. I am aware from being a forum member that Hartech are the "Go to" company to get an engine like mine rebuilt and I have no issue with that. However I have a question to ask that I would really be interested to hear peoples opinions on, are we saying that the only place that can be relied on to re build a 997 engine properly is Hartech? The question isn't meant as any slight to Hartech but the UK has many excellent Porsche specialists, surely there are alternatives that people have actually used and been happy with. There are plenty of specialists other than Hartech. Try SVP, Redtek, Parr Motorsport. For machining Serdi UK, Quasar Engineering, Swansea Auto Machining, CTM engineering.

Sump said: I'd take it to Autofarm purely on the principle that Hartech comes and intervenes in every thread scaring people and plugging his business. I know why you say that but you are wrong. Barry is a character and very much of the old school and if you spend 10 minutes with him talking about anything engine related you will understand. He is fascinating. And driven. It has to be his way, and if you go along with him he looks after you. He's not for everyone, but I don't take my 993 anywhere else. Its quite possible that he wont like my comments!

Baz - I was reading this the other day: http://www.specialistvehiclepreparations.com/blog/... Any comments?

dom9 said: Baz - I was reading this the other day: http://www.specialistvehiclepreparations.com/blog/... Any comments? I have ALOT of time for SVP ........ I dunno, they just seem to get the job done right. That is a really big knock at a competitor from them ..... To be honest I'm a little surprised by this, but then again they don't go public on forums I guess, telling us all about it and dishing the opposition. I remember having a chat with Dom years ago when he hadn't been going long, about all the hype you hear on here and other forums about different companies, from suspension gurus to engine builders. I was amazed at what a lot of Indies privately think of some of them and the times they have had to put their work right.

Lol, they only "warrant" their engine rebuilds if they service the cars afterwards.

Sump said: Lol, they only "warrant" their engine rebuilds if they service the cars afterwards. What would you expect!!! Customer has engine rebuilt by SVP, then takes it to a "bodget and scarper" for servicing, and you expect SVP to rely on bodget and co to do a proper service!! I am amazed at the tunnel vision that is shown on this and many other forums. Do you really believe that in this country there is only one company that can rebuild an engine, that happens to be a water cooled Porsche type? It is just an aluminium block engine, nothing special. Just because it has the word Porsche on the badge does not make it voodoo or black magic. From my experience these engines are being rebuilt on a very regular basis, by many different companies, and with a lot of repeat business. That means their own solutions to the Bore Score issues work. To all owners, do not believe everything you read on forums....you must all be pretty bright and street wise to afford a Porsche in the first place!! I am intrigued to know how the builder of the aforementioned engine got the gudgeon pin into the piston????

westwood35 said: Sump said: Lol, they only "warrant" their engine rebuilds if they service the cars afterwards. What would you expect!!! Customer has engine rebuilt by SVP, then takes it to a "bodget and scarper" for servicing, and you expect SVP to rely on bodget and co to do a proper service!! I am amazed at the tunnel vision that is shown on this and many other forums. So you'd be ok with buying a brand new Porsche and the only way for the manufacturers warranty to stay intact would be to have it serviced at a Porsche dealer?

Silly reply. Look at it this way: you rebuild my engine and invoice me £8,000+VAT. This comprises of £5k in parts that you have bought and £3k worth of labour that you could have billed for run of the mill repairs. Will you warrant the rebuild irrespective of who services it? Of course you wont, because you have the best part £6k of your own money at stake.

So if you are 400 miles away you still have to use them for servicing??

Some interesting responses, I'm just trying to get my ducks in a row for when the seemingly inevitable happens. My 2005 997S is a keeper so when the time comes I want to get it done properly but by the same token I don't want to spend £10k if I can get a comparable job done for say £6k. On a final point does anyone have any opinions on Northway Porsche? They are local to me and seem to have a very good reputation in general although I haven't heard anything about water cooled engine re builds(though I know that they do do them). Has anyone had a rebuild there or knows someone who has?

Some interesting responses, I'm just trying to get my ducks in a row for when the seemingly inevitable happens. My 2005 997S is a keeper so when the time comes I want to get it done properly but by the same token I don't want to spend £10k if I can get a comparable job done for say £6k. On a final point does anyone have any opinions on Northway Porsche? They are local to me and seem to have a very good reputation in general although I haven't heard anything about water cooled engine re builds(though I know that they do do them). Has anyone had a rebuild there or knows someone who has?

Hatech cover is ongoing if you take their service plan is it not? http://www.hartech.org/porsche_996_997_Boxster_lif... which seems pretty cheap compasred with "official" warranty - though appreciate may be a ball ache if you live too far from Bolton.

hartech said: Porsche (among others) used Alusil reliably and Lokasil reliably (when the pistons were coated one way). When European legislation stopped that type of coating for mass production the replacement used in Lokasil was not as reliable. Whenever Porsche had more to spend on a more expensive model they replaced those solutions with Alloy Nikasil liners (GT3 and Turbo) which will work well with almost any piston coating and have proved brilliant for them and us. For less expensive models they have returned to Alusil (but with a different piston coating this time). Please answer the question - if they already know how and why to use steel for racing - why do they not for road sports cars? I think you answered your own question here, Baz. I had cast iron sleeves fitted to my race 928 engine in an effort to solve the problem of finding a suitably coated piston. Given that this particular engine does not have to meet current emission standards and is usually run flat out with very little regard to long term viabilty, I think we made the right decision here. Now, you know the proces is not easy - it takes time, it takes highly skilled and trained personnel, and the actual parts are not cheap either. Porsche AG are in business to make a profit. They try and shave a € cent from the production costs everywhere. When you are planning a production run of 150k+ cars in the case of the 996 and countless more Boxsters, a saving of €1000 per engine looks like a great idea. Sometimes the idea does not quite work out, but I guarantee you, Porsche AG is still in profit on that particular "cost saving".

Sump said: churny said: Baz volunteers so much free technical info and always defends his reasoning, many others seem to snipe from the sidelines. Do other companies defend their solutions? Whilst talking about others and putting them down? He's purely doing it to plug his business. If he wasn't then he wouldn't even mention anyone else to promote his business in the way that he does. I find a wheel is far more efficient for grinding axes.

Long story short -I'll take that as a "Yes" for Nikasil Alloy Liners & a "No" for Alusil etching with Wossner or Mahle pistons.

We have built and tested engines with several different piston coatings and only 2 work well with Lokasil (currently still under test) while most didn't last any time at all. Most specialist piston manufacturers realise they cannot coat pistons to run in Lokasil and refuse to do so. One didn't and claimed they could and we spent a lot of money having them manufactured for all models without success - they were wrong. Our research into this subject has cost tens of thousands and is still on going and is looking promising but many more miles are needed before taking another risk on manufacture. Nikail on steel (or alloy) will be OK for purely racing engines designed for that purpose but Nikasil on alloy is IMHO the only way to do a proper job of a road Sports car. Most high performance steel liners also incorporate drilled cooling holes and a cylinder blocked designed with cooling and support specifically for the purpose. The M96 and M97 engines were not designed for that purpose - already have cooling issues and IMHO benefit from maintaining the alloy liner solution and Nikasil allows any kind of piston to work reliably. One final point - I am often accused of scare mongerring. I tell you what I find scary - that people buying ageing and depreciating cars only have the option of a new engine (often costing more than the car is worth) that embodies the very same faults or a rebuild incorporating them. Some have already realised it was scary to have iron liners fitted. A specialist contributor to this very post that seemed to support steel liners was in my factory last week on the third strip down of the same engine due to excessive smoking and oil consumption and after sending the block back to the supplier once already. We helped him (without charge) by measuring everything and advised a solution (and no it was not to re-fit our alloy liners as we knew that would be too expensive in fact we made nothing out of the advice we provided). The fact that there is a solution almost identical to the one Porsche use for GT3 and turbo engines and one that works well for hundreds of customers at a fraction of the alternative cost should in my mind make the position far less scary than not knowing about it. Furthermore the discussion about the merits of different solutions empowers owners needing help with alternatives they can decide on rather than having to trust just their local provider or a business promoting the only product they manufacture. I also resent the implication that by helping people who otherwise could not afford the repair at all (and have to scrap their car) by re-rounding good cylinders and then supporting them to prevent future distortion and cracking - by turning them into a closed deck design - is in some way sub standard. Not everyone who buys a sub £15K car can afford the best solution and providing one that is sufficiently affordable for them to continue to own and drive the car is an alternative we are proud to have developed and should not be made to feel we have to suffer for. It may not be as good as 6 new alloy Nikasil liners but it is far better than a new Lokasil alternative or (IMHO) steel or iron liners. Finally if other suppliers offered similar alloy Nikasil liners fitted in a reliable way - I would not be complaining or pointing out any problems - but sometimes there is a right and a wrong way to do things and I have every right to explain my reasons and allow others to similarly support theirs - although there is rarely anyone making a sensible and technically correct support for most of the other alternatives. Baz

Baz - is Hartech the only company in the UK who provides the Nikasil-coated aluminium liner solution?

No Autofarm do http://www.autofarm.co.uk/engines/water_cooled/sil...

Any word on how Nikasil compares to Nickel Ceramic?

If Autofarm do then that is a good alternative if they also machine the recess for the top flange to fit neatly into (as we do) but better than steel if not. However I could not see the use of aluminium mentioned in their advertising and was under the impression (perhaps wrongly) that they were steel. But at least it is Nikasil and a better solution than iron. Perhaps someone could confirm this issue (obviously I might be unlikely to be able to get an answer). Capricorn (formerly Perfect Bore) offer very high quality parts for industry at a very high level and there would be nothing wrong with the accuracy of their manufactured parts. Our components were designed by us and are exclusive to us Worldwide and I know of no other similar provision although that is not to say it does not exist. Baz

Nickel Ceramic coatings sprayed directly onto aluminium cylinder blocks and bored and honed are probably the future once productionising the process is perfected and cost effective. Having said that there was nothing really wrong with Alusil except the high machining cost (due to the hard material in all the cylinder block) and the change in suitable piston coatings that took place around a decade ago. Baz

Capricorn are difficult to deal with now, as they have some sort of agreement with a German company and this affects Porsche work.

Just came across a link to this advert on 911uk ....... http://www.ebay.co.uk/itm/Porsche-997-Carrera-2S-2...

Hello, There is obviously some sort of vendetta against Hartech by what looks like a fairly newly established Porsche specialist company trying to make some noise about rebuilding Porsche 996/997 engines..... I would say most Porsche specialists can rebuild these now as times have moved on but very few if any offer the in house services Hartech do on the newer water cooled engines. We used to build aprox 15 engines a year on 996/986/997 for other specialists and this has now gone down to around 5 engines as they have learnt to do them themselves over time. I have experienced first hand the Hartech factory and must say it is damn impressive for what is what I would consider a small business (under 50 people), he shares and contributes technical solutions on this and other forums for people to read and understand what is actually happening inside these engines. Obviously he is going gain financially from this and there is nothing stopping anyone else doing that either..... The machine shop they have is brilliant and the whole production cycle I saw whilst there was quite well thought out and presented, there were easily between 40-50 engines in all sorts of stages of the repair process. I was also shown one of their test cars (997) and it looked like something Marty Mcfly and the Doc had been involved with as there were gauges and wires everywhere! Doing yet further R&D work. I very much doubt most small Porsche specialists could dedicate the manpower and resources into this area at this level as it must run up £££££ worth of time and money... I am sure it will pay in the long term...... But someone still needs to fund it now. He should be very proud of what both he and Hartech have accomplished as it by no means a light task designing and reworking engines that have got inherent design flaws such as the 996/997 range. We have not used Hartech for engine work before as we used to install new crank case halves until they became too expensive! The engines we have rebuilt were normally all sorted via the trade customer and they came back with steel liners installed which looked ok but I was unsure if they would be compatible with a Porsche piston which we advised the customer and a large percentage of them were reported to have some issues, two of them were actually stripped down and found the piston had been nipping up in the steel liner as the clearance was too small and tight. Another one had the steel liner moving in the crankcase as it had not been correctly machined out. There are a few companies offering complete packages but I am confident that Hartech are the leading company in this field and will be getting all of our engine work form here forward. It is strange for one competitor to praise another but I am very envious of what he has accomplished and wish I understood more about the technical side as I am a self taught machinist with lathe and milling machines at work and find this sort of thing fascinating... When I left Hartech all I could smell on my clothes was the old fashioned machine shop smell of cutting fluids and swarf......I loved it and maybe he should consider selling tickets for Hartech factory tours! Just kidding. Hope you keep posting Barry and keep finding new preventative measures to help more and more people out. Mike

You're not a competitor to Hartech. You don't offer the same in house services and you don#t really have the same customer catchment. You're actually a customer praising their supplier...

Sump said: You're not a competitor to Hartech. You don't offer the same in house services and you don#t really have the same customer catchment. You're actually a customer praising their supplier... 2 Porsche garages that are not competitors...? We could both quote for the same work and jobs... roughly 30 miles from each other.

Unbelievable the lengths some people will got to in order to discredit anyone that disagrees with them. The only contact I have had with Mike for years is that when our 996 lost some power at Silverstone we used our diagnostic computer to diagnose a fault in the wiring loom but didn't have the circuit diagrams with us. Marcus Carniel was helping out (and lives near Mike and sends work to him) and unknown to us contacted Mike who sent us via the Internet the information that helped us check the wiring (finding no faults which later turned out to be something else electrical). Tom had to race with the fault that pushed him back to second in race 2 and finally stopped the car in race 3. After the event I E-mailed my thanks to Mike thanking a local competitor for taking time off work to send us that information to which his response was that we were welcome but as an afterthought - perhaps we could help him with his engine problem in return (which we were happy to do). Sports and Classic are our nearest competitor offering similar services and previously were one of only two or three others in the Country offering the same Lifetime Maintenance Plan as we did years before. I have no connection with them and we have done no work for them or raised any invoices for years (if ever). In fact I cannot think of anyone more similar to us and by coincidence no one nearer. They are therefore probably our nearest and previously our most similar competitor. We offered to help because we understand the difficulty he had with another supplier and that having less staff than us - rebuilding engines again and again (especially when it was not their fault) is hard to afford. Also we had the equipment to measure the surface finish of his liners and measure the sizes, clearances and shapes and find out the fault. In view of the circumstances and as compared to our daily turnover the time taken was relatively small and in view of the difficult position it put him in we made no charge - but that is the only connection we have had with Mike for years. I do hope those among you that have read the previous criticisms can take from this the right understanding of how to read between the lines in future and who to trust. Baz

sportsandclassic said: Hello, There is obviously some sort of vendetta against Hartech by what looks like a fairly newly established Porsche specialist company trying to make some noise about rebuilding Porsche 996/997 engines..... Mike That is extremely disrespectful, I'm assuming you have not been there and seen their setup or just what the background of SVP is. I've used amongst others, Northway, SVP and Hartech. Of all the Specialists over the years I've used, I would use all three of the above again, and none of the others I've come across. On each occasion they have done exactly what I have asked or pointed out what needed doing in a professional manner, but if you asked me which one was the best then I couldn't split them. I just can't see where it states Hartech on their blog ref the engine rebuild either.

Wozy68 said: sportsandclassic said: Hello, There is obviously some sort of vendetta against Hartech by what looks like a fairly newly established Porsche specialist company trying to make some noise about rebuilding Porsche 996/997 engines..... Mike That is extremely disrespectful, I'm assuming you have not been there and seen their setup or just what the background of SVP is. I've used amongst others, Northway, SVP and Hartech. Of all the Specialists over the years I've used, I would use all three of the above again, and none of the others I've come across. On each occasion they have done exactly what I have asked or pointed out what needed doing in a professional manner, but if you asked me which one was the best then I couldn't split them. I just can't see where it states Hartech on their blog ref the engine rebuild either. I was the first to post the link to SVP to ask Baz's opinion as I had looked up SVP for something else, the other day. I have never used them, nor Hartech. It seemed reasonable since this thread was about using (or not as the case may be) iron liners as Baz had seen some failures, yet I had noticed the other day that others had seen replacement ally/ Nikasil liner failure as well. SVP appear to have seen more than one, in the relatively low number of engines they rebuild compared to Hartech, so I was interested by the failure rate, which is what these threads usually discuss. They haven't stated that it was a Hartech engine and nor has anyone else. This is all getting a bit weird now. Baz doesn't need defending against some phantom organisation. I certainly enjoy his posts having a degree in Materials Engineering and working in thermal-hydraulics everyday of my life... As well as having owned an M96 engine that was used hard on track and survived nicely over 80k miles before it was sold. There are a lot of people in the US (where I live) doing a lot of work with these engines, for example Jake Raby: http://www.flat6innovations.com/ Some of Hartech's analysis agrees but not all of it. I would guess that Mr Raby has seen more engines than even Hartech, being the biggest name in a much bigger market. The problem, as I see it, is that Porsche really, really did test these engines extensively prior to release. And they got it wrong. Without a lab and testing the original engine design to destruction varying many, many variables - most of the analysis we see from all parties is supposition and guess work, even if it is educated guesswork/ engineering judgement. Clearly a number of engine rebuilders have seen a number of rebuilt engines fail for various reasons. Thus, the conclusion appears to be that there is no perfect solution at the moment or perhaps the failure modes are not fully understood... Can we discuss without the name calling and over-enthusiastic defence?

I don't agree - there appears to be one failure out of thousands of Nikasil alloy liners I know about (with a perfectly reasonable explanation) and we do not know if or why the other one failed despite it being it seems in a warranty period (if indeed it was one of ours) now why the engine could not be rebuilt or repaired and if it was just a liner it could have been fixed so why was that not done?. Despite answering questions supported with technical reasoning and experience - I have asked several questions myself which are never answered. Why have Porsche never used iron or steel liners for any road sports cars for at least 35 years, what do SVP do to repair a scored bore, does Autofarm use steel or iron or alloy liners, and a new one - what does Wraby do about scored bores etc. If someone will answer those questions and collate the number of engines each has honestly repaired in the last 12 months I will then be happy to divulge our numbers for comaprison. The posts have taken on an almost surreal position where I find it hard to recognise the logic and relationship people are putting to simple posts and taking extraordinary positions that don't even make any sense. I realise success breeds its own problems but never expected it to be at this level or intensity. I am not sure myself what does and what does not amount to unfair or unreasonable public criticism intended to damage a business when hiding behind a made up name or trying to make it obvious who is being referred to by obscure links but I am taking advice and if it is possible to do so I will happily test out the situation to ensure the truth and fair play are followed in the UK. Baz

Baz, rest assured that there are a number of us who are open to learning about the strengths & weaknesses of various sleeving options for 911, 928 & 944 alloy blocks & your input is genuinely appreciated. Yes - some people have an agenda, others may be trying to impress with a technical knowledge & experience which is veneer thin - but there are others who are trying to weigh-up the competing options which exist & are trying to get the most balanced impartial analysis possible. It's a chicken & egg situation - a vendor amy have done the experimentation & research and on the basis of that hard-won experience settled on an offering which they believe to be the best solution - this could be regarded as reasonably impartial if the basis for arriving at that solution is as empirically-based as possible. Conversely some vendors may have decided on the basis of their existing experience & skills what solution they are readily capable of offering - even if they haven't experimented with the alternatives - and will defend their solution even in the face of overwhelming evidence to contrary. Most people can differentiate between a customer-centric solution & a supplier-centric solution. Is the vendor's business based on serving the needs of the customer or merely based around what they're prepared to offer?

Can I clarify that although I posted that link to the advert within this thread, I to am an engineer by profession and follow with real interest and admiration all that Baz writes regarding these engines, and his door would be the first and only one I come knocking on if my engine ever fails It also appears the advert has been pulled now, making it look increasingly like an underhand attack.

hartech said: I don't agree - there appears to be one failure out of thousands of Nikasil alloy liners I know about (with a perfectly reasonable explanation) and we do not know if or why the other one failed despite it being it seems in a warranty period (if indeed it was one of ours) now why the engine could not be rebuilt or repaired and if it was just a liner it could have been fixed so why was that not done?. Baz - NO ONE is saying that the liner SVP is referring to is one of yours! You have a thread that says all 'steel' liners are bad. This one. That doesn't make ally nikasil liners better, I am sorry to say. Because, the materials may only be ONE of the factors that cause a rebuilt engine to fail. There is nothing at all unreasonable about saying that or PROVING that there have been failures of rebuilt engines with ally nikasil liners. Not all ally nikasil rebuilt engines are better than iron sleeved engines, clearly, as some iron sleeved engines are still running about and some ally nikasil have failed. hartech said: Despite answering questions supported with technical reasoning and experience - I have asked several questions myself which are never answered. Why have Porsche never used iron or steel liners for any road sports cars for at least 35 years, what do SVP do to repair a scored bore, does Autofarm use steel or iron or alloy liners, and a new one - what does Wraby do about scored bores etc. I, for one, are not putting you or your process down. Again - the defence was on the (deliberate or otherwise) suggestion that all ally niaksil liners are better than iron liners. That wasn't fair. And if you're saying that it is only Hartech that can be trusted, on the evidence that some ally nikasil rebuilds fail, then this is very much bordering on advertising. The details of what the others do are available (in quite some detail, for some) on their websites or they can be called. Choosing not to advertise on websites doesn't make them any less knowledgeable or specialised. I also believe there was a casting/ machining/ time benefit to Porsche building engines the way they do... AS WELL AS a potential technical benefit. The thing is, the technical benefit didn't pay off. hartech said: If someone will answer those questions and collate the number of engines each has honestly repaired in the last 12 months I will then be happy to divulge our numbers for comaprison. YOU say that you have seen and fixed many more than anyone else. For you to have seen 15 failures of iron liners and yet someone, who must fix many, many less engines (according to you) to have seen at least two ally nikasil rebuild failures, suggests the number of ally nikasil rebuild failures must be high enough to make it very reasonable to ask your opinion on the SVP website. AGAIN, for clarity, in the knowledge other people provide a similar solution to you - I WAS NOT CALLING YOU OUT FOR BUILDING THAT FAILED ENGINE. I just wanted your opinion on what was written there as there is a suggested failure mode. hartech said: The posts have taken on an almost surreal position where I find it hard to recognise the logic and relationship people are putting to simple posts and taking extraordinary positions that don't even make any sense. I realise success breeds its own problems but never expected it to be at this level or intensity. I am not sure myself what does and what does not amount to unfair or unreasonable public criticism intended to damage a business when hiding behind a made up name or trying to make it obvious who is being referred to by obscure links but I am taking advice and if it is possible to do so I will happily test out the situation to ensure the truth and fair play are followed in the UK. Baz I haven't called you a name on here, nor disagreed with any of your analysis, other than saying your post sounds like advertising (and I am far from the only one) and to say that people should not be driven to a ally-nikasil solution over another solution because there are many, many other reasons why it might fail, beyond it being the a better material . I have always recommended ANYONE on here who needs a rebuild to talk to you if they are up North and Autofarm if they are down south. You have a huge experience base and post some interesting technical stuff but this isn't all rigorous analysis and with ally nikasil rebuilds demonstrably failing, people MUST make their own minds up about what sort of rebuild they want and who they should use. Painting it as if ONLY ONE provider is capable of producing a good rebuild and they have done ALL the analysis required to provide the solution is simply not accurate. Penguinracer said: Yes - some people have an agenda, others may be trying to impress with a technical knowledge & experience which is veneer thin - but there are others who are trying to weigh-up the competing options which exist & are trying to get the most balanced impartial analysis possible. Exactly - some of us like to know and understand the options to the fullest extent and have every capacity to understand and challenge them. That does not mean that we are out to get you but when you 'publish' on a public forum, you must be prepared for the inevitable scrutiny. No matter what the motivation for that scrutiny is. Your 'success' is based on something, frankly, terrible happening to people who bought Porsches. Your help and support is welcome and appreciated, without doubt. In fact; without you many people may not even be able to drive and afford their cars. But if your expansion is funded by more and more of these failures then you can't expect competitors not to spring up and cost/ value will be a big part of the equation. If someone goes for a cheaper solution and 'it works' then there's nothing to say there is anything wrong with that. You've put a lot of your knowledge in the public domain... I suspect this will be 'used', quoted and repeated elsewhere. If someone falls for an inferior rebuild, produced by a company other than Hartech, because they were told that ally nikasil was the only right solution and it later fails - They've been led down the wrong path. YOU posted this as the very first line of this thread: hartech said: I have been commenting for some time about the problems associated with recent practice of fitting steel liners to the M96 and M97 engines... You don't fit steel liners, others do. If you start a thread about the 'wrongs' of others - it doesn't paint you in a good light. By all means start a thread extolling the virtues of YOUR CHOSEN solution but don't blanket put down anyone who provides a steel solution. hartech said: I am taking advice and if it is possible to do so I will happily test out the situation to ensure the truth and fair play are followed in the UK Threatening legal action on a public forum won't win you friends and business here, especially when you started the thread. I'm sorry I seem to be the only one who has stood up to defend what they have written as others have been bordering on rude but that last quote is painfully ridiculous. Edited by dom9 on Wednesday 2nd July 19:40

hartech said: I am not sure myself what does and what does not amount to unfair or unreasonable public criticism intended to damage a business when hiding behind a made up name or trying to make it obvious who is being referred to by obscure links but I am taking advice and if it is possible to do so I will happily test out the situation to ensure the truth and fair play are followed in the UK.

Sump said: You're not a competitor to Hartech. You don't offer the same in house services and you don#t really have the same customer catchment. You're actually a customer praising their supplier... Youre a bit of a tool, aren't you? *makes note: Sump is a clown - ignore*

GC8 said: Sump said: You're not a competitor to Hartech. You don't offer the same in house services and you don#t really have the same customer catchment. You're actually a customer praising their supplier... Youre a bit of a tool, aren't you? *makes note: Sump is a clown - ignore* I don't think Sump was entirely clear but I think you've been a bit quick to judge there, GC8... As much as I don't agree with the content of some of Sump's posts on this thread, Mike did say: "There are a few companies offering complete packages but I am confident that Hartech are the leading company in this field and will be getting all of our engine work form here forward." So Mike is NO LONGER competing with Hartech for engine rebuild business and IS a customer of theirs. That is relevant in context. Other services, yes, they most likely compete but that isn't the argument here.

I don't disagree with you. My comment was more as result of all of the lame posts that Sump has made in this thread.

GC8 said: I don't disagree with you. My comment was more as result of all of the lame posts that Sump has made in this thread. Understood

The fact that a small percentage of rebuilt engines everywhere may fail (which I have always pointed out) does not in any way diminish the difficulty for those who's engines have failed in deciding the best way to repair them nor the benefit they may accrue from reading about the issues and available services and products. Dom9 - can I respectfully ask under what level of experience, expertise and practical evidence do you feel you can state that "not all Nikasil alloy liners are better than iron sleeved engines"? What is the difference in you stating that and me stating the opposite - that they are? - is it a question of considering the level of capability, proven experience and numbers successfully rebuilt that people should be able to place a degree of "likelyhood" about who is most likely to have the best opinion more likely to advise them about the better solution? I notice not you nor anyone else answered any of my simple questions once again. I have always tried to answer every question and supported it with technical explanations or evidence based ones. There is no evidence of Nikasil alloy liner failure except my own of one cylinder caused entirely by other factors entirely (that had nothing to do with the cylinder bore material). No explanation of the cause of the other apparent failure, no reasoning about why an engine could not be rebuilt, no contact with me to advise about the failure (despite - if it was an early one of ours it being in warranty). We have manufactured and fitted several thousand and so one failure caused by nothing connected with the choice of liner or cylinder coating is far better statistically than anything we have seen from a much smaller number of iron and steel liners or even of Porsche's own standard bore linings. It is right that lots of other factors could contribute to an engine failing. Not everyone (for example) will agree to have other future proofing done to their engine (i.e. only having one cylinder replaced in a bank that we all know suffers from potentially any of the three failing). Crankshafts can fail, cars can overheat etc etc. without feedback from those who might strip any engine there is no way to be sure the cylinder or its Nikasil plating is at fault. We do not even rebuild all the engines many are just cylinder blocks repaired and returned to the specialist for rebuild themselves. I find it interesting also that a business thinks it promotes their own ability to admit they could not work out how to assemble an engine when clearly someone else had - and I cannot help but wonder if this is why the cause was deflected to a competitor. Mike is not a customer of ours yet but after seeing for himself the quality of the product, the skill of the employees and the organisation - and having experienced problems with both steel and iron liners - it looks like he is convinced about our provision. Are you trying to suggest that having already had to pay himself to rebuild engines because the liners that others have fitted have failed he is in some way expecting ours to be no better but is promoting it to become a customer? what exactly is your sniping point about this that makes any sense? Bearing in mind that most of the engines we removed iron liners from only had one liner fitted - the proportion of iron liners we have replaced is very high indeed compared to the small number that were built and that we have had specialists sending them to us to replace after failure admitting they originally fitted them on the advice of those making them and to save a small amount of money (that was lost rebuilding a second time), do you expect me to simply keep quiet and allow lots of innocent owners to similarly be persuaded to fit them without making my experiences public? If someone else supplied similar alloy Nikasil liners fitted in a suitable way - would I criticise that - NO! I found there were several different posts all basically asking about the suitability of iron liners and kept providing a similar reply and though the evidence against was so strong I thought perhaps I should point out my experiences and feelings once and for all. This did not stop anyone else providing a counter argument (which I expected) but did allow the public needing help (even if their numbers are small) to make an informed decision rather than be persuaded into something we have seen fail again and again - AND that all the technical evidence and experience from Porsche themselves supports our type of solution (which it is entirely free for others to offer as well (except I suppose those who make a living from supplying iron or steel liners only). There is nothing to stop proper technical and evidence based argument from allowing people to make their own minds up but the level of point scoring and personal abuse that has littered this post bears no connection to that. No one answers my questions, there is actually no evidence of Nikasil alloy failures (even though one or two out of thousands would not in itself be as many as for iron and steel), Porsche do fit liners to engines that are extremely reliable and they are Nikasil alloy liners - why did Porsche not fit steel or iron liners (answer please) if they are a good alternative (and please don't try and make out they would be more expensive). I have had extensive technical discussions (and even had components tested) with personnel from the original manufacturers of the crankcases, pistons and Lokasil technology, with Mahle, with Wossner and many other specialist suppliers and piston coating businesses - have those offering counter arguments similarly collected their own evidence and conducted their own research at the same level? If steel or iron were just as good a solution as Nikasil alloy liners our prices would be slightly lower - our turnover would increase and we would have a bigger share of the market. It makes no difference commercially to us to fit whatever is proven to be the best solution but could be better to offer an inferior alternative (which we have rejected). Some others who want to get a share of the market (nothing wrong with that) can see that the slightly lower cost of steel or iron gives them an opportunity to get work and offer something different to us. If it was in our opinion a good alternative why would we not offer it as an alternative to those with less to spend? the answer is really simply. We stick at the only solution we know is best and works more reliably, despite it reducing our market share, because we would not want to supply a product we know has a high probability of failure or dissatisfaction (and anyway the cost difference is minute and we are considering investing in production equipment to bring prices in line eventually anyway). I am sorry I cannot sit by and allow owners to waste money on solutions that come back for re-work in higher numbers than can be explained if the product was OK and do feel it is my duty as an expert to point out (with supporting technical arguments and comparisons) why I think Nikasil Alloy is a better solution. This is only "OUR" solution because I think - so far - we are the only ones offering it. None of what I post is not true - all of it is directly to the point and supported by evidence I see (and my credentials can stand up to scrutiny). Porsche use the very same solutions. Some others that post on here do not support their position with sensible technical arguments and do not answer salient questions, instead they use the classic politicians solution to deflect the argument somewhere else, to irrelevant points and personal insults. When will we see some sensible, objective, technical arguments and evidence to support all the opposing claims and points and when will someone answer my few simple questions? (of which the most relevant is perhaps why Porsche use Nikasil Alloy liners and not steel or iron). Unapologetic Baz

hartech said: If Autofarm do then that is a good alternative if they also machine the recess for the top flange to fit neatly into (as we do) but better than steel if not. However I could not see the use of aluminium mentioned in their advertising and was under the impression (perhaps wrongly) that they were steel. But at least it is Nikasil and a better solution than iron. Perhaps someone could confirm this issue (obviously I might be unlikely to be able to get an answer). This page on the Autofarm website suggests your assumption was correct Baz, in that Autofarm use steel with Nikasil. Out of curiosity (and not asking in a way that suggests the answer would make one solution better than the other, before anyone implies such), do Hartech offer any options to increase capacity with your rebuilds? If not, is it something you have considered, or have researched and deemed too risky? Just curious. http://www.autofarm.co.uk/engines/water_cooled/pri... Autofarm website said: Silsleeve cylinder replacement The existing Lokasil liners are machined out and replaced by steel liners plated with the well proven low-friction Nikasil running surface. These SilSleeve liners are specially designed to have a top flange which provides more support at the mating face with the cylinder heads, known as a closed-deck construction 'Big-Bore' conversions By using Silsleeve liners Autofarm are now able to provide several options for substantial capacity increases: 2000-on Boxster 2.7 to 3.0 litres 1998-2001 996 3.4 to 3.7 litres 2000-on Boxster S 3.2 out to 3.7 litres 2002-2005 996 3.6 out to 3.9 litres

GC8 said: Youre a bit of a tool, aren't you? *makes note: Sump is a clown - ignore* This ^^^^ - about time someone said it. 'Clown' is very polite in the circumstances.....

You see my problem and thanks for your post. If you look back it was stated that Autofarm also supply Nikasil Alloy liners as a matter of fact which now seems untrue and shows what I am up against. We don't know who is contributing, we do know at least some of the responses against my posts are not true, they almost never answer questions or substantiate their position, experience, familiarity with the product or repairs etc etc but they do post as if their information should be given equal consideration. This is the reason I state the numbers we manage successfully, why I refer to what Porsche have and have not done, why I explain technically, why I take my position, and why I mention the numbers of alternatives that have failed - not to brag, certainly not to get any more business, but purely to add fair and reasonable weight to the posts I do provide enabling readers to apply some form of value to my posts compared to others and this is all done to protect them from making serious mistakes (as it is clear many others have already done). I am genuinely sorry if this impacts on businesses involved in the supply of steel or iron liners but they already know themselves that many of them have not proved very successful and I think their customers deserve to at least be informed of an alternative that I think is better so they can make an informed choice. I didn't start mentioning any businesses by name or implication, I just stated as a technical matter of fact what the position is with different solutions and backed it up with some numbers and proportions to support my descriptions. I have only mentioned names after others attributed things to them that were either mis-conceived or I thought inaccurate. Just one more point - if one of our liners failed within our warranty period (and was clearly just caused by us or our products) we would honour our warranty and not charge the customer for the subsequent repair. This has not occurred yet but another benefit of our large scale operation, turnover and capacity is that the cost of that is relatively smaller for us compared to our monthly engine repair turnover (and relatively easy to fit in) whereas for those with much smaller capacity it really would be difficult for them to afford and manage and stay in business (and I doubt that any compensation was paid to those who made all the iron or steel liners we have replaced except one instance where I am told it has (but am not prepared to reveal any more about). It is a very difficult product to repair - for a problem not caused originally by anyone than the original manufacturer and life is tough enough anyway in our game without making it any worse. Regarding the legal position - I have for some time been wondering how far people can go with lies and misleading comments while hiding behind a veil of secrecy and thought it was about time to find out (and am doing so). This should not put off anyone expressing a genuine opinion or stating true facts or technical arguments (which I would welcome) but it might force them to substantiate their points and be able to stop those spending more time trying to discredit competitors with losely directed mis-information and underqualified opinions that would mean that readers will be able to trust the content better in future and be able to make better decisions - whatever they are. Well we have one answer so far - I look forward to the rest and until then I think everyone knows the issues and different opinions and it is reasonable for me to lay off a bit until there is something of substance to deal with. Baz

Just in the office (US timezone) and catching up... Was about to post the link to the Autofarm website, which is very clear about using Nikasil bores with the correct pistons/ rings and that they were designed by the engineering legends over at Capricorn. They certainly conform to Baz's idea of a good engine rebuild, by all accounts, but they do offer the potential for increased capacity which is VERY nice to have when your engine pops as it's nice to feel you're getting 'more' for your money than Porsche gave you in the first place. The only thing that I've never been 100% sold on is the closed deck. Yes, brilliant for block strengthening (which was required for the M96, by all accounts) but the ability to cool the cylinders may have been reduced. Having said that - perhaps if the new cylinders don't distort etc, it's less important?! Your thoughts on the closed deck and Autofarm solution, Baz? As I understand it, Flat 6 Innovation and LN do not produce liners which are closed deck, in the US. I believe they are the worlds largest M96/97 engine rebuilder. Right, will address some of your questions as quick as possible and I'll check-in later if you want further info... Why did Porsche use Lokasil? As I understand it, it was for cost saving. Yes, Lokasil has some benefits as it provides a harder wearing surface etc but the process of 'creating' the Lokasil by 'pouring' the casting material material over the silicon matrix is a much, much faster, thus cheaper, process for mass manufacturing the engine. It requires less machining and aligning etc than sleeving the bores and as the part is 'cast in', it can't slip. Re-reading this I just found a quote from Wayne at Pelican Parts who is undoubtedly one of the world's greatest Porsche authorities: "Engine Casting Porosity: As mentioned in the previous section, Porsche used a new cost-effective method to cast most of the oil and water cooling passages directly into the engine case. This reduced the total part count for the engine and also helped reduce assembly time and production cost. Unfortunately, the advanced casting technique seems to have led to a number of engine cases experiencing what has been called “engine porosity.” There is not a lot of information available on this problem, but it seems to be related to problems with the initial casting process." A further cost saving, as I understand it, was over-boring the original engine for later models so the walls got thinner (later changed) and had the potential for more distortion and the stiffer silicon matrix became prone to cracking. There was no technical benefit for them do this. It avoided new castings. It was all money, money, money. I am sure, however, they tested this in the lab and many trials and signed it off as working just fine... One suspects that Porsche tested that solution more than all the engine rebuilders in the world have cumulatively tested their solutions. And they got it wrong. I suspect they wish they had gone with the Nikasil bores now, as they did in the GT engines! Actually, my background is in the behaviour of metal matrix composites under load at temperature. The experimentation (I've spent many days in the lab squashing etc pieces of aluminium/ silicon inside a little 'oven') and reporting of those is what gives me an interest in this topic. I am an engineer by degree(s) and deal with metals, fluid flow and heat transfer everyday. I've also owned (and upgraded) an M96 car so have followed your (and others) 'research' extensively and even procured an M96 and pulled it apart in the lab. I have no dog in the fight. I do not rebuild them, I have not designed a solution and I owe none of the commercially interested parties anything. Like I say - I am not here to bag you, just to challenge your (and everyone else's) work so everyone FULLY understands the problem. We may never get there as I simply don't think anyone is 'proving' what the the problems are - just providing a solution because they believe the issues are X, Y, Z. That's not to say anyone is wrong, it's just not clear why different solutions still work equally well. If the problem is 'stiffness' then the open blocks (in the US) would not work. If the problem was heat transfer the closed blocks would not work (Autofarm). Clearly it's a combination but what combination? We know that heat and strength are the main contributing factors but what 'ratio' for want of a better word? What is the 'optimised' solution? How much thought has been put into rod angle/ piston force for the longer stroke engines? I am not saying iron/ steel is better than Nikasil, at all. I thought that was very clear. Nikasil is the better material in this application. My issue is that WHATEVER solution is used, the manufacture, machining and fitment of the liner (as well as who built and signed off the engine build) is perhaps the far bigger unknown. I can't have been that unclear as cmoose picked it up (although he/ she may be a very smart cookie for all I know). I would rather take my chances on an iron/ steel liner, designed and built by the worlds greatest engineer (for example) with the appropriate pistons/ rings than have someone rebuild my engine using Nikasil liners who has never handled one before, machined the block and sleeve himself to what he thinks are appropriate tolerances and just gone with them. Especially if the latter is more expensive. And THIS IS WHY I RECOMMEND HARTECH. Not because you understand failure modes or have designed a solution but because you have been refining your design over time such that the chances of failure because of design and manufacture are almost zero. I couldn't care less that your solution is Nikasil, to some extent - I care that you have working engines. If your solution had been iron/ steel and LN/ Flat 6 had been bagging iron/ steel - I wouldn't write you off as I could rule out ANY OTHER issues. Steel/ iron can be made to work. There were many, many (and maybe still are) re-sleeved blocks produced and the simple fact ANY are still running and ANY Nikasil rebuilds have failed suggests the potential is there for some iron/ steel rebuilds to be 'better' than Nikasil. Maybe not over say 100k or maybe not under some extreme condition but they are out there and working day-to-day. We'd have to ask SVP about the failed Nikasil blcoks they have seen. As I say; I do not know them and I do not know whether or not that is a Hartech block. You also do not seem sure. Again - I would much rather have an iron/ steel liner by someone who has successfully built say 100 engines (running for say 10k) than a Nikasil liner from someone who is building their first engine on the back of internet advice. I don't know how to explain that point any better. Plastic may be a better solution than Nikasil under those circumstances (to be fair, a plastic engine did run in Group C - bonus points for anyone who know who that was). So, yeah, we seem to be having an argument, which was never meant personally from my side and I am not bagging Hartech or the Nikasil solution. I am asking for some objectivity and for topics like this to be 'spun' the other way. I'd rather a thread was not started with 'steel liners are s t' but was started with 'we believe Nikasil to be the correct material because...' - it's a subtle but important difference. There are numerous quotes in here that look very much like advertising. Your product and time/ effort put in on here speak for themselves. I have nothing to sell and don't care what people think of me... It would seem I am not the only one who thinks that there are some toys/ pram behaviour going on here and blatant advertising. Why do I care? I don't, massively, but I find these very technical threads that I have interest in written from a sales perspective and that ruins it for me and does you a disservice. I hope I have not encouraged any 'clown' behaviour and don't agree with it but people must be free to make their own choices and MATERIAL SELECTION is just one of the selection criteria that should be used when selecting your rebuilder. Lokasil would have probably worked fine if Porsche has kept the bores nice and thick... How many 2.5 failures were there compared to say 3.4 or early 3.6? Nikasil might still be better as a material but it would have never been worth changing because Lokasil would have worked. Do you see the point? In fact, I read on another thread that the US Class Action lawsuit contains failure rates in it. Don't quote me but I think it was something like ONLY 2.5% for 3.4s and 7.5% for 3.6s... So, the early 3.4s that people seem to hate and quote (generally) 5-10% failure rates for seem much better in that much bigger sample market.

My name is Duncan Andrews and I am the owner of Westwood Cylinder Liners. We supply cylinder liners for a wide range of engines, including the water cooled Porsche engines. We were made aware of the problems that the 6 cylinder water cooled engines were having about 4 years ago, and customers were buying our universal repair liners which had suitable dimensions for 96.00 and 99.00mm bores. Within a year or so we were asked to produce a specific liner for each engine (less cutouts and holes). These second generation liners have sold in their hundreds, and led us to produce a Ductile Iron liner which has all the cutouts and holes machined for each individual cylinder. We have sold these all over the world and have one particular customer in the UK who has at least 6 sets a month. Cast iron liners have been used in Aluminium engines for many years, and continue to do so. Look at all the American V8 engines that are aluminium with cast liners. The fitting of the liner is the most important thing, generally involving liquid nitrogen and a suitable oven! This is the important point with regard to the liners. There is a specific way in which the blocks need to be machined, then the liners need to be fitted in a certain way, and of course final finishing after fitment. I have no issue with what Hartech do with their engines, and it is a solution that works. BUT, cast iron liners in these crankcases work as well, and as pointed out are considerably cheaper. I have a reputation to keep with my business, and would not sell a product that was "not fit for purpose" We have reacted to market requirements, and acted accordingly. In all the time we have been selling these liners for the water cooled Porsche engines, no one has come back and said they do not work. We have over 25 companies in the UK that use the liners, and they keep coming back for more!! Our sales are increasing month on month and we expect this to continue. I do know of companies sourcing liners from other suppliers overseas, so cannot make comment on the quality of their cast iron products. I know our product, and am fully convinced it is suitable for job. It is also fair to say that the sales of these liners within our business make up for less than 2% of our overall turnover, so we are not doing this to make huge profits, its because our customers have asked us to produce them. We will continue to sell our product and keep up with the ever increasing demand from our customers for the cast iron liners. We do not fit the liners, but we can highly recommend a number of Porsche specialists and engine machinists that work on these engines on a regular basis. Some of these are well known companies, that have seen the benefits of the cast iron liners. Please contact us directly for more information. We will not discuss any technical information or fitting requirements on any forum or webpage, because once its on the internet its there forever!! We work by talking to our customers on the phone or face to face. There is no hiding behind a screen and you get to ask all the questions you want. Hartech has mentioned "the legal position". I have spoken with my lawyer this morning, and we are quite prepared to take further action with any company that continues to make comments about my company, that are blatantly not true. If anyone has an issue, including Hartech, then pick up the phone and talk to us. In our world this is how things are done. Might be a bit old school, but you will get a straight honest answer and you can then make your own decision. I hope now that certain people will accept that there is such a thing as competition!! Some may not like that fact, but it is life.

Hartech have pointed out that they have had to repair a number of engines which have been rebuilt using steel liners (of whatever provenance) and none that have had the nikasil. The suggestion was that this was not just statistical, but due to the steel ones (or the rebuilding using steel) being not ideal for this application.

westwood35 said: We will not discuss any technical information or fitting requirements on any forum or webpage, because once its on the internet its there forever!! We work by talking to our customers on the phone or face to face. There is no hiding behind a screen and you get to ask all the questions you want. Thanks Duncan - That was one point I was trying to make in defence of other companies not posting. I've said my piece so I think I'll bow out and watch from the side lines now. Apologies if I took this off track. Edited to add, based on the responses I missed: ScienceTeacher said: Hartech have pointed out that they have had to repair a number of engines which have been rebuilt using steel liners (of whatever provenance) and none that have had the nikasil. The suggestion was that this was not just statistical, but due to the steel ones (or the rebuilding using steel) being not ideal for this application. The point being... A material doesn't need to be 'ideal' to work. Other rebuilders HAVE seen Nikasil re-lined engines fail. It CAN fail. Westwood has seen steel linered engines work. anonymous said: [redacted] I haven't checked back - was it 70 engines or 70 liners? 70 liners could be as low as 12 engines. Your point is well made though - a lot are going pop and ALL owners need to understand every remedial solution they have had made available to them and understand the implications, on a fair basis. Edited by dom9 on Thursday 3rd July 20:52

I agree it is nice to see some professional comment and better for everyone to read sensible comment from those directly involved. Dom9 Can I ask you a few questions please. Did you do as we did and machine out the outer alooy to leave the Lokasil liner so that the material can be tested for tensile and compressive strength, stiffness and impacr resistance and creep? and did you do the same with Alusil (as we did)? We found Lokasil to be much more brittle, weaker and prone to creep than Alusil and it was then no surprise that the crankcases suffer from "creep" causing ovality. The alloy that the crankcase is made of is also less stiff than the original Alusil and so the combination of that alloy plus Lokasil we tested was much less strong or stiff than the comparative results for Alusil - yes the block cylinder wall thicknesses were found the same or thinner than the 944/968 Alusil alternatives and no wonder they gradually creep oval in time. This has been measured in every single engine we work on and generally after 50K there is around 5 to 6 thou ovality (0.1 to 0.15mm). The ovality is not consistent and different Lokasil preforms clearly have different production quality. We have also found different dispersion of silicon within those preforms (that could be a contributory factor). Liners crack around 10 to 12 thou ovality usually around 80K to 140K (but the difference in consistency and loading from different drivers influences the rate of load and therefore creep). Closing the deck with a thin alloy ring not only prevents further movement (we can actually reduce the ovality and re-round oval cylinders first that are not yet cracked) and the thin alloy ring actually increases the surface area in contact with coolant and does not reduce it so heat transfer is not an issue. Dom I guess you know the difference in thermal conductivity between a Nikasil alloy tube in direct contact with the coolant and a steel or iron liner inside an alloy sleeve (or on its own in direct contact with coolant) and can confirm that there is nothing better to transfer the heat away to the coolant than the alloy liner. Technically tou are qualified to confirm that two tubes (even of the same material) fitted inside each other are not as stiff as one homogeneous sleeve of the same dimensions. You will also I am sure confirm that an oval cylinder creating high piston to cylinder wall clearances will inevitably result in more blow by past the piston rings and a higher piston face temperature to start the cooling process and less heat conducted through the oil film as a result which will then be thinner and offer less support to avoid lose silicon crystals impinging on the piston and cylinder bore face. I have asked the technical expert at KS (who manufactured the crankcases) why they have returned to Alusil and his answer was that Lokasil was too expensive. I could not get him to confirm if that was because of the basic production costs or any replacement costs incurred for failures but it was clear they thought it would be cheaper (as it reduces overall machining time) but didn't turn out that way. The above influences older 3.4 engines and smaller but will almost certainly eventually affect larger engines that seem to score bores first. Bore scoring is largely because the combination of a less hard surface piston coating was combined with shorter rods and larger capacity engines increasing loading between the piston face and cylinder wall with less hard surfaces in contact. The biggest problem with the engines is actually the fact that the coolant flow is uni-directional and not contra-directional on bank 2 (which fails for scoring) but the opposite on bank 1 (which does not) and we are developing a solution to this which already tests show has worked. I can understand that the idea of getting more performance from the cost of a rebuild can be attractive but the reason we do not provide this service is largely because we regard the engine as more fragile than previous Porsche engines (in which such changes usually work OK) and prefer to stick to the standard rebuild. Our main concern is the unusual overhang of the rear flywheel journal connection combined with the relatively narrow rear main bearing shell (that feeds oil to number 6 big end). This massively increased overhang (compared to most other Porsche and almost any other engine design) increases crankshaft flex and can wear the rear main bearing and result in big end failure. We feel that the performance of the cars is not such a big problem as the reliability and prefer not to push the boudaries any further. There is still a lot of confusion about steel and iron - some liners are Nikasil plated steel and some unplated iron. I have not been able to identify the source of the iron liners we have seen fail but there are clearly several different suppliers. I agree that if they are being fitted by several different businesses there is always the possibility that some do not do as good a job as others. I have only ever seen one set of steel liners and they were fitted well )but still had the liner surface proud of the block to allow for the different expansion of the alloy and liner so they close when at running temperature. This is not needed with an alloy liner as the liner expands exactly the same as the block. As long as the liners don't slip or twist (and we have seen both) and the fitting clearance and block height corrections are right and the bore clearances correct then they should work OK except they do need more cold piston to cylinder clearance to allow for the lower expansion rate when at running temperatures. The precision machining to fit those liners correctly is essential for them to work and it is clear many are not doing that correctly. We are asked almost daily to supply our alloy liners (particularly abroad) for others to fit but have refused (despite the obvious commercial benefit to our profitability) because we carry out all that work exclusively "in house" totally in our own control and are not prepared to risk the product reputation by puting the most important element in the hands of people we don't know. We may reconsider in time after vetting the businesses involved and after technology exchange with contract protection. Quite apart from that many that previously have fitted iron liners do not have boring equipment to accurately set clearance depths or circular interpolate the top flange diameter (which cannot be done in a full machining sweep in all models) and indeed some suppliers who do fit liners don't actually machine the top hat flange diameter - so although it looks like it converts the top to a closed deck it actually leaves it floating. It does not work as well as alloy - machining the cylinder top block after assembly with iron or steel because differential expansion can then allow the liner to drop at running temperatures (dependent on the exact design location etc). The head gaskets do not have enough pliability to take up miss alignment of top flanges (as more tradditional ones did). The flange thickness that supports the liner from tilting is quite narrow and in our opinion it is essential to support the liner at the top in a precision machined location which I think we may be the only supplier doing so (please correct me if I am wrong). Many appear to fit but on closer inspection have a clearance gap. Many iron liners do not even have a top flange and just fit inside the original alloy sleeve. We have as a favour previously fitted iron liners to racing engines with no problems but with great accuracy of machining and heat and pressure controlled fitting and I have always said they are OK for racing when the running temperatures do not vary as much as in a road sports car and there are no emission issues either. Of course owners driving more modestly will usually get more mileage out of engines and those driving them hard will get less (and many have more than one owner and no way of knowing how they were previously driven. Perhaps some people do not do a good enough job of fitting the liners and others are better - we simply will not take that chance as it is more important than the liner being fitted. However having said that we have been involved in problems with steel liners that were fitted OK but still had issues with oil consumption and smoking that we put down to piston to liner clearances. My enquiry about the legal position is about those that do not name directly but make sufficient clues to make it obvious who they are directing their comments at and then after that to also inquire whether it is acceptable to just say something caused a failure without actually any evidence (as you have already seen statements on here that later prove wrong or untrue and this is very unfair). Obviously if action can be taken then those facts can be brought to light and the truth uncovered - which would be to everyon's benefit. I will be happy to defend anything I have stated if necessary as to it being true and accurate - there are others making implications that they do not support and that are clearly designed just to damage a specific competitor - which I do not believe I have done and this should be stopped - tell people what you do instead or general comments about a products type of suitability I think are OK but aiming a criticism at one business without any actual evidence should not be possible without redress.. If I had to make a sweeping conclusion I guess it would be that iron or steel should work if fitted correctly but are not technically as good as Nikasil alloy and in our experience have a significantly higher failure rate. This may well be because many fitting the liners are not doing a high enough quality job and this may relate to the fact that few have sufficiently accurate equipment and machinery to manage the job to the right clearances necessary (that is the case in the ones we repaired). The cost differences are not great but difficult to equate if the fitting is not being done by the liner supplier but by different businesses, although my information about the cost of fitting of steel liners is very little different to our prices for what I think most would agree is technically and evidentially a better solution. Still not had any more answers guys - come on - I am not afraid to talk turkey - why are you? why did Porsche not use iron or steel in road sports cars but do use Nikasil Alloy liners very similar to ours successfully when they are more expensive?. This engine range were designed for alloy cylinder blocks and the coolant flow design is proven suspect for that - adding the less effective cooling of different materials and expansion rates is hardly going to be an ideal alternative unless the block was so designed in the first place. Answers please, Baz

ScienceTeacher said: Hartech have pointed out that they have had to repair a number of engines which have been rebuilt using steel liners (of whatever provenance) and none that have had the nikasil. The suggestion was that this was not just statistical, but due to the steel ones (or the rebuilding using steel) being not ideal for this application. Playing Devil's Advocate for a moment: (i) The absence of a negative is not the same as proof of a positive; (ii) Evidence of a coorelation is not the same as proof of causation; (iii) Statistical significance is not of itself evidence of causality - it's merely an indicator of correlation. (iv) Control experiments involving the elimination of all potentially confounding variables are needed as the basis of any investigation of causality. It would be interesting to view the sample size of motors with Nikasil Alloy liners v those with various iterations of Iron & Steel liners. We shouldn't put all Iron & Steel liners in the same category. We need to segment on the basis of spun v ductile iron, and for steel different commpositions of iron & carbon. Then there are coated iron liners,coated steel liners, wet liners, dry liners, closed deck, open deck, machining tolerances issues, & block/liner temperatures & press pressures used during the liner installation process to further confound any analysis.

Baz, could you please explain a bit about why the temperature extremes are such an issue on a water-cooled motor. Doesn't the cooling sytem keep the engine within a reasonably small thermal range regardless of whether it is being thrashed or not? I can see this being an issue on an air-cooled engine, but don't understand why it should be the case on a water-cooled motor (assuming said cooling-sytem is working properly of course). Cheers.

Baz - 4th of July here so on and off the net for the next few days! Honestly we could agree about thermal gradients through metal and thermal gradients through different metals quite happily, but the level of expansion of these metals seen inside an engine is very much open for debate, I suspect, and I don't believe anyone outside of engine designers is measuring that. My reason for joining this thread was, first and foremost, because I enjoy reading your well-considered technical analysis of the engines. The reason my posts could be argued to have taken a negative turn towards Hartech was that I felt the 'technical analysis' leading to a ferrous metal being the WRONG material was unfair, especially when many, competing, manufacturers (as we have seen) have built many engines, many of which are still running. I think my point has been made. I do AGREE with you that Nikasil is the best solution but it is NOT THE ONLY solution that can be made to work. I too would have a Nikasil engine built but I would go with the larger capacity from Autofarm, though I'd consider us 'friends' and expect them to look after me if anything went wrong, though I am sure they would anyone. Hence - I was not putting down the Nikasil solution or saying it wasn't right but I was defending other solutions, despite having no allegiance to anyone providing other solutions. Why? Because I just didn't think it was fair to say that Niaksil is effectively the only material that will work. Imagine if someone had logged onto this thread having just spent £5-£10k having an engine rebuilt with some kind of ferrous sleeve! There is nothing (that I can see) in your technical analysis that guarantees it will fail. So, a lot of this does read like an advert, does read like scaremongering and the analysis doesn't include the thorough testing of all the other types of liner materials. And, like it or not, Lokasil is (theoretically) quite clever and could well be up to the job - I've left the book I wanted to quote from at home but it was used, in main, for cost saving purposes. These are not race derived engines (like the GTs) that are built in relatively small quantities, they wanted to hammer these things out in all sorts of capacities and minimise the machining to get those capacities. They got it wrong. But considering the US Class Action includes for IMS etc (I believe) the actual failure rate for bores, specifically in the 3.4 engine, which people seem (historically) most scared of, was very low at probably 1%-sih (being 2.5% for all failures). If 1% of Nikasil rebuilds fail I doubt we'll here much about it as the numbers out in the world are much, much, much lower than the number of M96/7 engines produced by Porsche. If lots of ferrous sleeved rebuilds fail - who is to say that is because of the material and not because the liners were incorrectly manufactured or installed - I suspect no one is going to get hold of all those engines to find out. Other materials can be made to work. They may not be the best solution but that's a cost:benefit analysis for each owner to consider. And, like Is aid yesterday, now that some balance has been restored on this thread by Westwood and others - I don't think I need to be seen to be the one banging the drum for others as Nikasil is a solution I would support, personally. If I get really, really bored next week, maybe I'll model the heat transfer through the different liner materials, in a water jacket and then take a look at the expected expansion and we can all see what we think. Apologies for not answering your questions in full, especially when I didn't mean for the response to be this long! No more talk of lawyers from anyone please! Let's celebrate the Septics independence from the Greatest nation on Earth instead

That was as always interesting Dom9 but I think slanted as a response rather than one looking at both issue equally - however at least it is fair minded and I appreciate that. I too hate the idea of litigation but there have been other instances on here (including this one) where untruths have been printed as fact that can harm a business and as I run one and contribute I thought it was time I found out what the law says. Apparently you can take action for deformation even if it is by inference (which the court can decide) and as a result get internet sites taken down etc. Armed with that information I am finding out more but rather for potential long term responses so as a director of ltd company I know what I am talking about in future and this is actually a responsibility directors are supposed to take in the execution of their duties - that I have not previously found out enough about. Regarding heat transfer etc pistons are manufactured barrel shaped, oval and tapered (and the top where the rings sit small enough not to touch the actual bore). The amount of taper, ovality and clearance has to be designed for the maximum heat which is generated at maximum load - i.e. flat out. At lower power outputs (which most road car engines run at most of the time) the taper and ovality is too much but has to be this way to allow for the most extreme conditions. The more powerful the car usually the greater the amounts and the bigger the piston diameter the greater by proportion as well. This makes the right clearances difficult to achieve in engines capable if huge output but used mostly at very low outputs. The heat is generated in the piston crown area and dissipated through the cylinder walls via the oil film and contact area. The lower the output the less area is in contact and the hotter the cooler the piston face. Even when the coolant is at the same temperature - the temperature gradient between the piston face and the inner cylinder wall is higher as is the oil film temperature and it increases with output even if the coolant temperature is the same. But it isn't the coolant at the surface is hotter but as the engine speed is usually higher the flow rate increases as does the cooling rate. It is this problem that explains why bank 1 is OK and bank 2 is not - because the thrust face runs hotter on bank 2. Anything to lower the oil film temperature between the piston and the cylinder wall will reduce problems on bank 2. Alloy cylinders (like for like output) will dissipate more heat and keep the temperature lower. There are other solutions that will also help which we have tested and are due to announce soon. Enough for now the weather is good and the weekend is here - the race cars had a great test today abd all in the World is well - and I don't want to spoil that until next week so you all have 2 days free to drum up counter proposals or even to answer those questions you all seem to avoid! Have a great weekend everyone! Baz

I think over the last few years of contributing to these forums I have learned a few things. One is that many people write things that are not actually true as if they are. Others manipulate the medium to discredit others - some fairly - some unfairly. Some post for a bit of glory others genuinely try to inform people to help them understand things more. Even in this I am beginning to realise there is a possible problem. You need a lot of different background information and technical experience in different subjects and actual practical experience of stripping and working on a lot of these engines to be able to draw helpful conclusions. Sometimes a specialist in a very small area of expertise picks up on more general comments but doesn't have all the other links in the chain to form an overall conclusion and sometimes this unfortunately muddies the waters. Their specialist posts are often accurate in their own right but not relevant for some other reasons outside of their specialist area when considering all the implications and issues influencing a failure. I find I am writing more and more to explain things and that may be it would be more productive to re-vamp our well out of date buyers guide (that does contain valuable pictures, drawings and experiences) so that I can refer to that more often than have to try and re-write answers to help people understand the issues better and save a lo of time and accusations of various manipulation of the medium. So unless something crops up that I feel needs more urgent attention I will instead re-write the buyers guide sections top bring them more up to date instead and then make the various sections available to try and answer readers questions. The problems that the M96 and M97 engines can experience are complex. They don't affect every engine and they are clearly marginal OK or failures depending on some outside factors. They are clearly operation near to the margins of reliability and it can take little in any direction to push them over it. I will be reporting on the results of the tests and new products to help prevent bore scoring all together soon however as I feel time is of the essence on this issue. Meanwhile I would advise not to necessarily believe all you read and make sure there are others supporting posts or not before taking them too much on board. The best protection I can suggest is to try and establish who is managing the most reliable rebuilds for satisfied customers as this must be a good way forward. Baz

Baz - with all due respect to Pistonheads - it's principally a forum for consumers, tyre-kickers and light-hearted banter. If you're worried about what options boxes to tick down at your local OPC or want to solicit opinion as to what colours have the best resale value - then PH is your place. If you really want to discuss Porsche engineering with guys who are constantly modifying, improving & re-engineering these cars - then you need to be on Rennlist. More so than Europeans (perhaps Scandinavians excepted), American car enthusiasts view a large manufacturer's offering as a basic platform with designed-in compromises for a wide consumer market - as such it is merely a blank canvas to be developed to the owners unique requirements. I'm constantly amazed at the standard of the many US-based amateurs whose fabrication, welding, machining and design skills exceed that of many so-called "Professionals" I've encountered in the UK. No doubt that's a legacy of the hot-rodding, fearlessly experimental, can-do attitude which pervades the US engineering scene - in everything from matters automotive to IT & software engineering.

I've now worked as a Design Engineer for over 12 years, most of that time in motorsport and high end performance cars such as the T.50. I once crossed paths with Barry Hart as a younger man, more than 12 years ago and so sadly I didn't have the knowledge at that time to really appreciate his work. As a lifelong Porsche fan and lover of the 996/997 era cars, it pains me to see how many of the M96 and M97 engine cars are now being rebuilt with 'iron' inserts, because they are significantly cheaper (to make, not so much to buy) as a short term fix. This, in my professional opinion, is not an equal replacement for this application and offers serious disadvantages, particularly thermally. How much more likely they are to result in premature engine failure it would not be professional for me to comment. However, I perceive the risk that a great number of engine blocks are being affected by lower performance repairs and engine blocks fitted with these liners will potentially be beyond repair and scrapped if/when they fail again. It feels like a terrible waste and an avoidable future catastrophe for 996 and 997 era cars if only buyers could be educated. For all the reasons mentioned in this thread and many more, the best way to repair an all aluminium, high performance road engine is with Aluminium liners that are Nikasil coated exactly as Hartech have been doing for many years. If your 996 or 997.1 engined car suffers a bore score related failure, please DO NOT fit iron (steel) liners. It's is not worth the short term saving.

I raced a 3.4 Cayman which had been rebuilt with steel liners ... due to late arrival the engine was run-in during qualifying for the first race of the season. The car did a little over 1400 miles before the engine seized towards the end of the Bentley Straight at Snetterton ... the engine even requiring a new crankshaft ... an £8000 rebuild. That one certainly didn't work well !

Holy thread resurrection! The fact that 997 and 996 engines can be rebuilt properly by people like Baz makes the these cars really attractive as a great balance of usability and handling/ performance. Clearly the market doesn't agree hence the values, which in turn makes them even more attractive in my book. £12-£14k is not nothing, but it's not the end of the world, unlike the potential costs of repairing an out of warranty 991 GT3 engine, for whom a clear independent rebuild path is not as clear. Hartech guys, do you, or do you intend to get into this market as the cars exit the 15 year Porsche extended warranty window? I know where my money is going when I get tired of my Ferrari and want back into the Porsche brand.

clintonward said: £12-£14k is not nothing, but it's not the end of the world, unlike the potential costs of repairing an out of warranty 991 GT3 engine, for whom a clear independent rebuild path is not as clear. I think it is the end of the world when the car in full working order is only worth about the same as the rebuild cost. The cost of an engine for a car worth eight to 10 times as much, or whatever, doesn't really matter. Not many people are cross shopping 987.1 Caymans and 991 GT3s. To be clear, I think the Hartech rebuild (more like £15k-plus inc VAT for the full job these days) is great value, especially compared to an air-cooled rebuild. Very high quality. But it's a huge cost versus the value of the cars being rebuilt and generally isn't really reflected in resale value. You'll only get a small fraction of it back if you sell on.

f6box said: I think it is the end of the world when the car in full working order is only worth about the same as the rebuild cost. The cost of an engine for a car worth eight to 10 times as much, or whatever, doesn't really matter. Not many people are cross shopping 987.1 Caymans and 991 GT3s. To be clear, I think the Hartech rebuild (more like £15k-plus inc VAT for the full job these days) is great value, especially compared to an air-cooled rebuild. Very high quality. But it's a huge cost versus the value of the cars being rebuilt and generally isn't really reflected in resale value. You'll only get a small fraction of it back if you sell on. Which is why I opted for an upgrade to 4.1. Feels a bit more like a new car (which is in part thanks to everything else that was done "while we are in there"). Skint but happy.

How (not) to rebuild a 992 GT3RS engine .... ?

The sight of the water draining out of the diff and PDK after having not been drained for months and the look on their faces is frankly something else....

The views alone in the vids on that car probably paid for it! Fair play to him, I think he is great compared to the other boring drivel YouTubers taking crap with a coffee and a rolex on show.

I agree, I found it fascinating to see the complexity ... but would you buy that car ??

Popolou said: The sight of the water draining out of the diff and PDK after having not been drained for months and the look on their faces is frankly something else.... It's similar to when they got that Cullinan fixed and they set off to Switzerland with their Lambo Urus in convoy. I immediately said to my wife that it was going to end in tears with wide tyre summer tyres and snow. Quelle suprise, dad chucked the lambo off. Admittedly he was only going slowly, but dread to think of the outcome if he had been going downhill.! Them shopping for 23inch snowchains was amusing as well. Got to admire their determination and positivity though!

Youforreal. said: The views alone in the vids on that car probably paid for it! Fair play to him, I think he is great compared to the other boring drivel YouTubers taking crap with a coffee and a rolex on show. Can't fault the work ethic, but all the disingenuous nonsense every time about "this is the only way I can afford xxxx, my dream car" is a turn off. Unclear why the false narrative / jeopardy is required. He's clearly engaging to a broad audience, do they really turn up because they buy into the idea that he is living on the edge for the umpteenth time? Maybe! He's doing the numbers, as you say, so he's obviously getting it right in pure commercial terms. But there's a bit of a whiff around the whole endeavour.

Niffty951 said: As a lifelong Porsche fan and lover of the 996/997 era cars, it pains me to see how many of the M96 and M97 engine cars are now being rebuilt with 'iron' inserts, because they are significantly cheaper (to make, not so much to buy) as a short term fix. You do know that Porsche now use iron liners in the 992? Aluminium block, iron liner. It's a bit more complicated than tapping an iron liner in on the bench with a mallet and hoping it'll be ok, but it's an iron liner in an aluminium block - proving that when installed properly this notion that they'll all go boom is basically scaremongering nonsense. The biggest problem with iron liners is that they're available from numerous sources, with questionable quality, and sometimes fitted by people of questionable talent. Despite the scare stories I haven't seen evidence of many failures on the whole of the internet, but when I have seen them fail it was always down to the installation and very occasionally a cheap and nasty liner that broke. I've never in the twenty years I've been searching, seen any evidence of one failing just because it's an iron liner, it was always a fitting or quality issue. When fitted properly they'll outlast everything else on the car.