" NEW" Mahle 3.6 Piston for cast iron cylinder liners

As you may know, Mahle has been making Porsche pistons since the beginning of time, and is a Premium supplier for most OEMs in their high performance models as well as all forms of racing from F1 to dirt track. I found it surprising to see in their Motorsports catalog listings for 2 Piston/ring sets for water cooled M96/M97 engines. One for use with cast iron replacement liners, and another for Nikasil liners . The listings are for Cayman/Boxster 3.4, 996 3.6, and 997 3.8 engines. No application for 996 3.4 engines.... Is it possible that there are cast iron liners finally receiving success in the market? Maybe the LA Sleeve Pro Cross/ Pro Flow liners? I wouldn't think too much of it if was one of the smaller piston company's listed them ,they will build you anything you want, but usually a special request won't make it into the catalog, but when Mahle lists them, it has my attention....

While I dont know how many successful steel liners there are,, there are plenty of examples of high performance engines that do fine with steel liners in a AL block , While there is a lubricity difference between the Alusil or Nickosil bores vs steel, I suspect it depends on the skills of the guy that sorted out the install, Dry sleeves are simple but technical to do right, wet sleeves require way more skill.

I wonder if the 99 or 100mm 3.8 pistons (for cast iron bore) could be used on a 3.6? Are stroke, rod length, and deck height the same between 3.6 and 3.8? LA sleeve shown part number P996H is the same wet sleeve for 3.6 and 3.8, and bore up to 103mm.

I know this is a hot potato but why wouldn't steel liners work in M96 engines? (I have read a few threads about it, is it due to thickness?) Just curious to why.

Thickness is more of an issue with "dry" sleeves. I think most of us can agree "dry" sleeves are a bad idea.

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from my basic understanding. (no expert here) The idea is in Dry sleeve, iron and aluminum expand and contract at different rate when heating up or cooling down. Some thread have shown picture of the iron sleeve rotated after some times. I think the tolerance is much tigher in a M96 makes this a very difficult thing to get right. Other expert may be able to explain better. I think Wet sleeve would work but it is probably very difficult to do it right since the iron sleeve has to mate up to the aluminum block. If this can be done right with iron piston, maybe then the expand rate would be the same and have less issue? However, I don't supposed iron wet sleeve would be much cheaper than a bore and coated aluminum one?

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Yes the 3.8 pistons will work in the 3.6, same stroke, rod length, deck height, CC's ect...

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thanks! Good explanation

Since aluminum has roughly double the expansion rate of aluminum, clearances of a cold engine need to be extra large to accommodate a piston that grows faster than the bore. Extra large clearances on a cold start up can result in clatter at start up, possibly oil consumption? Also press fit of the wet sleeve into the block has to remain tight when the aluminum block gets hot. Too little press fit= loose sleeve, too much press fit= cracked block. These are still things that are commonly done on other engines. Not sure how the m96 is different.

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If you look at the Mahle pdf above, the installed clearance listed for piston used in iron sleeve and Nikasil sleeve is the same at .0008 - .0016. Personally I would stay to high side .0015 to keep from sticking a piston. The common material used for these forged pistons is 4032 hypereutectic which doesn't expand as much as forged 2018 pistons (which expand more and need a lot more cold clearance like .004). Nikasil sleeves give less friction, and a better ring seal which gives a few more pony's, but is the most expensive process. The full Nodular iron "wet sleeve" should create a more stable bottom end as long as head gasket sealing is adequate. But will give up a few pony's.. LN has the process downpat and is the way to go unless someone has mastered the M96 ductile iron sleeves/aluminum combo to the same degree. It should be a less expensive process, but who knows if it has been perfected.

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Are those clearances at running temp? that doesn't seem right, especially if it were at room temp. Maybe I'm reading the pdf wrong.

The correct name is ductile iron. And yes it is successful in its application when done right. So no sleeves but complete cilinders. This is done by one of Germany�s most renowned rebuilders. https://9lf.de/gb/content/30-water-boxer-engine-repair if your German is good enough it reads better then their basic English translation. https://9lf.de/de/content/30-wasserboxer-motorreparatur

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Yep, at 70F, not running temp.

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I changed the name to Nodular Iron, is that OK? BTW Nodular Iron/Ductile Iron are both still in the "cast iron" family whether they are pour cast or spun cast.. Thankx for the link !!! I'm glad they are having success !!! But the price 600 Euro? (680 usd) Is that for the set of 6? If so would be wonderfull !! If for each, would be $4080usd, not so wonderfull....

Ah no problem of the naming. At the end we know what it is. Yes 600euro for 6 I think. But they are not sleeves so need special machining and fitting into the block

Seems odd that we don't have many examples of wet ductile sleeve repairs, since the pistons and sleeves are catalog items. I wouldn't be that surprised if a few of us rennlisters are unknowingly driving around with ductile sleeves right now, possibly due to undisclosed repairs.

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Yes, they are more of a hybrid half cylinder/half sleeve, but over here they are commonly called "wet sleeves".. Since you speak the language, do you think you can confirm the price? If it's 600 Euro may be worth the cost to ship the cases over the pond, or compare the price to what they charge here.. Possibly, who knows.. I haven't seen any of the Nodular Iron wet sleeves failing, you would think the pictures would show up here..I'm OK with giving up a few pony's to have a solid bottom end at bargain price..

Subscribed!

I installed a 2.0 Cosworth 4cyl (BD deries) about 3 years back, Dry sleeves, cost was US $1800, including parts. Included pulling the worn/damaged stock sleeves, truing the bores, installing new sleeves. The engine ran at about 9K on track (Midget) with Hillborn and methanol, the original sleeves got toasted when a head gasket got weepy and soaked the bores.. I watched the guy install them, he did a lot of measuring, making sure both the hole in the block and the sleeves were Round and the same size, centered and properly spaced. The bores got a precision hone job after the sleeves were in to make sure they had a surface that the rings could bite to break in. Took about 6 hours. Not included in the block work, He used Cometic head gasket with a dense ring that matched the flange at the top of the sleeve so the sleeve could not move. The fripping head gasket was like 450.. so its not all the the machine work.. LOL He baked the block out at 200 for 12 hours, let it cool to room temp. Dry iced the sleeves and pressed them in. There was a coating of some type on the sleeve to help it stick in the bore o.f the block, there was a pair of staked spots on the bottom of the sleeves to prevent rotation.

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When I sent my engine to FSI for a rebuild, this turned out to be exactly the case^^^. There was a question of whether LNE (they do the machining and fitting of Nickies for FSI) would be able to properly machine and fit the new cylinders to my case... Thankfully they were able to do it without further complications! 🙂

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Not exactly, I remember your case was a result of "iron dry sleeves" failing due to the parent material failure. I still haven't seen any failures of the full Nodular Iron "wet sleeves"..

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Iron sleeves? Closed deck? One word: BOOOOOOST

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LMAO.. exactly !!! I have been thinking along those lines for a long time, If only I were young again (sigh)..

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They show a comparison in their website First two cilinders are sleeved the third is a solid cilinder acording to their method. In more detail For me such a solid nodular graphite steel cilinder is the perfect material. And a very good alternative for nickie sleeves. It forms one single piece. The additional coating for the nickies bring in an additional risk of coating deficiencies. I think these free standing cilinders which are secured into the bottom of the case are a very good alternative to nickie sleeves when it comes to durability, long life and cooling efficiency. Why dont you call them. They have experience with international customers. They could give you first hand information. When my engine needs a rebuild I will go with them without any hesitation.

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The translated version uses the word "glue" when referring to how the cylinders are installed. Is this a bad translation? Or are they actually gluing cylinders in?

Every few weeks we are seeing engines come in fitted with iron cylinders now.. Some people don't even know they have them, like @dporto didn't know. The biggest issue is coming from dissimilar metal corrosion, which is forming where the two materials meet, and is being catalyzed by electrolysis, and certain coolants not developed for these compositions.To make matters worse, distilled water isn't being used, which just catalyzes the catalyst even more. In these cases, the block can't be used, and the entire project is compromised by a big question mark. Two weeks ago we sent 14 blocks to the scrap yard that were fitted with iron/ steel cylinders, as they were too compromised to be utilized for our processes. These are things to consider, that you likely won't be told otherwise, and likely would never think about, until it finds you.

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Need a good core?

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Not at the present.. You need us to build it for ya. It won't be steel, or iron clad, though.... :-)

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That's the plan but I'm still 2 years out. Just wanted to throw it out there if you ever need one (I still have one running well) before then.

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Jake, is this what I'm seeing? (see attached) Do these sleeves actually come apart in operation or just crack or what?

Yep.. These are classic photos of what is being experienced. The best part is they leave all the crappy parent material in place, and cylinder pressure opens up the top of the bore to begin this process, where the parent material meets the steel sleeve. Dissimilar metal corrosion is a great catalyst for exfoliation, which is the most aggressive type of corrosion that aluminum alloy can experience. While iron cylinders could be made to work, I have yet to see any efforts to do this be proven long term. The piston is just one part of the equation, and it's the easiest part to solve... That said, most of these engines have to run so much cylinder to piston clearance to (keep from seizing in the bores) that the engine sounds like a small diesel.. Guess what picks up on that? The knock sensors. Guess what that does to ignition timing, and EGT? Try it, and see.

We get blocks that have been either patched with one or two sleeves, maybe just bank two, or even some fully sleeved with both wet and dry steel sleeves. We've seen it all. Most we can fix - it usually involves making a custom sleeve to fit, as long as they haven't cracked the block. With steel sleeves, an interference fit is required. There was an article in the AERA referring to steel sleeving alusil blocks (Audi 4.2 V8 in this instance) and the writer noted that if you put the same interference between the steel sleeve and the block as you would with other applications, the block would crack. If you don't put enough, the sleeves will rotate like this: Rotated steel sleeve If the block is cracked due to too much interference, usually it's cheaper to find another case to start with than try to fix it. Here are just a few examples: These are all different engines that had been previously repaired and had to be rebuilt a second time.

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There have been zero instances of problems with our plating and sulfur in fuels. In fact, most fuels available are ultra-low sulfur for emissions purposes. When people bring up the argument of sulfur and Nikasil, I always point out that Porsche used Nikasil from the 70s on with zero issues. The problems experienced primarily by BMW were as a result of issues with their process. Flaking or adhesion issues with the plating we use is not an issue unless some sort of foreign object debris is ingested or if the parts are improperly machined or handled prior or during assembly. In any of those instances, the iron/steel liner would also be damaged and require replacement. In rare instances, I've seen engines that have detonated to death or lost a connecting rod, but our cylinders have maintained their integrity with some loss of plating, however in those instances there was nothing left of the piston or there was a chunk of rod embedded in the cylinder. Again, the steel sleeve wouldn't do any better.

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LOL,, glue yes, I think the more correct term would be "bonding agent". Anytime two machined surfaces are press fit or shrink fit together, there is actually only 30% metal-to metal contact. the bonding agent can fill in the other 70% and make for a 100% contact for more holding strength and stability. Loctite alone makes about 10 different bonding agents..

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Correct. They will leak if you don't use a bonding agent. We use Loctite with a 24 hour cure in our fixture followed by a controlled baking and cooling cycle to achieve full cure. Blocks are pressure tested at 40 psi prior to shipping to ensure they good to go.

Here is an example of a dry sleeved Cayenne block that once we removed the sleeve, we found the parent metal to be cracked.

Most of the people who look at the cost difference between Nickies and some of the alternatives don't know what they are looking at. We pressure test every block and every bore is checked by us, not the platers, for ovality, taper, and surface finish. Decks are also resurfaced for proper MLS gasket finish and to correct for distortion in the deck. When you compare what other charge for wet sleeving, our cost isn't all that much higher. The biggest issue people have with us is the longer turn around times - the plating process adds significant time. But back to the Mahle Motorsports pistons - I work closely with Mahle Motorsports. I've been working with them to expand their Porsche catalog and as you can see, quite a few of the SKUs use our Nickies cylinders. If Mahle Motorsports didn't have trust in us and our product, we wouldn't have a partnership with them. They will be adding more M96/M97 pistons when I have time to give them all the specs. For the record, the only difference between running any given piston in iron vs aluminum/nikasil is the clearance, as most modern thin, low-tension ringsets are compatible with both cylinder types. Ultimately, like many other threads on this forum, it's up to those reading to make up their own minds as to what is best for their own situation.

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If the Loctite seals as well, it may prevent corrosion between the two, as there wouldn't be any coolant present in that area. Darton Sleeves offers a coating they claim will help with corrosion, that combined with proper coolant might help a lot. Does anyone key or pin the sleeves to keep from rotating?

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I have no doubt Nickies are a fantastic product. I was very happy with your IMS Solution and other products I purchased. I may end up purchasing Nickies at some point. Not knocking you guys in any way. I'm just trying to learn more.

What many people here don't realize is that the pictures shown here of the failed iron sleeves are the result of the "parent material (aluminum)" failing or the result of improper "press fit/ shrink fit" or the result of overheating. The better process would be to machine away the entire cylinder and replace it with an iron one as is now being done by some shops.( La Sleeve, Albert Motorsports). Alusil, Lokasil, Silitec , DiASil, Mercosil, ALBOND, Nikasil, PWT (plasma wire transfer) were all designed why? To replace iron as a cylinder surface.Why? Because iron heavy. But iron based material is still being used in many many aluminum automotive engines for cylinders, and in ALL extreme power engines, and in all commercial stationary engines as the complete block/cylinders( they don't care about weight).. Nickasil has been around for 50 years, I've said it before, and I'll say it again. Nikasil or LN "Nickies" are the best there is (although the most expensive) , I have said so, I have recommended them, I have used them in engine builds, what more can I do? Nikasil and iron based are the only two cylinder surfaces that don't need a coating on the pistons to survive.( although coatings can be used). It may end up industry wide the Nikasil process for all engines except low budget or extreme high pressure engines. Iron sleeves or liners can be from ten bucks to a couple hundred dollars, and can be from 30k psi tensile strength to 130k psi. From grey iron to Nodular iron. From 1/8 thick to full cylinder liner thickness. Grey iron 30k psi has been used to make complete engines for over 100 years due to the natural graphite "flakes" content makes a good wear surface for cylinders and for valves (with no need for added guides). Some high performance engines were cast from Nodular iron. ( Australian 351 Clevland blocks, Brazilian 2.3 TurboCoupe blocks ect.). Nodular iron the process causes the graphite flakes to form spheres or "nodules" and or much higher strength, stable,even better suited for wear surface. I have seen high Nodular iron blocks with 200k on them and still no wear. Bottom line 3.4 up m96 blocks need the entire cylinder removed and replaced with good iron cylinders/liners or "Nickies" cylinders/liners. The LA Sleeve Pro Cross/ Pro Flow iron cylinders/liners cost $2279 installed, 600 of that is the cost of installation, so the cylinders/liners are $279.83 each. Still seems quite high to me, guess they have a lot of overhead. This is just one data point.

Today’s liner-less aluminum engine blocks allow for smaller high output engines with reduced weight, tighter bore centers, and larger bore sizes than previously possible with a similarly sized iron sleeved aluminum block. This allows for an increase in displacement and output without the need for increased cooling system capacity. Improved thermal conductivity also allows water jacket depths to be reduced 30 to 65 percent, reducing engine weight and cooling system volume, which improves engine warm-up and reduces emissions. For the same reason Porsche went from iron to biral then to aluminum with aircooled engines, a great example of the elimination of the iron liner in the aluminum block is Toyota’s first all aluminum MMC engine - the 2ZZ-GE. This block used preforms with ceramic alumina-silica fibers and mulite particles rather than Lokasil’s selective reinforcement with silicon and alumina. Pistons are similarly electro-chemically treated with an Fe-P (Iron and Phosphorus) plating for wear resistance. Toyota’s first engine using MMC technology was used successfully in performance vehicles by Toyota and also by Lotus in the Exige and Elise. Toyota found they were able to produce 26.17% more horsepower and 4.65% more torque with the same 1.8 liters of displacement by eliminating the cast iron liners. There are many other examples, such as the Porsche 944, as outlined in the paper they published in the SAE when developing its new (at the time) all-aluminum Alusil engine block versus the 924's iron block.

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This is all true, I agree with all of it, except I question the 26.17% power increase from replacing the iron cylinders on the 2-ZZ engine. There is a lot more differences between the 1-ZZ and the 2-ZZ than cylinder surface, like compression ratio 10.0 vs 11.5, boreX stroke even though both were 1.8L( 2-zz was oversquare for high RPM) ,camshafts. 1-ZZ was a low rpm torque, fuel efficient motor(140hp), 2-ZZ was a high RPM power motor.(180hp). According to Mercury Marine, Mercosil gives 6.8% more power at 2500 RPM, and 1% more at 6000 RPM over iron cylinders. The problem I have with all these specialized cylinder materials, and all the different piston coatings ( I think it's getting out of hand) you can't just bore the cylinders .020 over and install new pistons/rings, bearings ect. and have a fresh motor. The older I get, the more "conservative " I get. I want my engine easily/inexpensively repairable, I want my air compressor to have a cast iron cylinder, I want my lawn mower to have a cast iron cylinder.( and to have available oversize pistons/rings.) I don't want to "throw them away and buy a new one" because it's too expensive to repair..

�The older I get, the more "conservative " I get. I want my engine easily/inexpensively repairable, I want my air compressor to have a cast iron cylinder, I want my lawn mower to have a cast iron cylinder.( and to have available oversize pistons/rings.) I don't want to "throw them away and buy a new one" because it's too expensive to repair..� ^^^ This!

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Agreed that they did more than just change from iron cylinders to aluminum, but my point was that eliminating the cast iron liners provided significantly increased thermal transfer, allowing for the engine to make that power reliably. These engines have been optimized by reducing water jacket depths and cooling system volumes compared to engines with iron liners. There is a huge difference in thermal conductivity between cast iron and even different aluminum alloys: Nodular iron (Durabar): 32.301 W/m-K Gray iron (Durabar G2): 53.329 W/m-K A390 (Alusil): 134 W/m-K 6061: 167 W/m-K The M96 engine isn't a Mitsubishi 4G63 or Honda K20 engine. Those crankcases are stout castings can handle being fitted with steel sleeves no problem. Granted, most of the people who build high output engines based on these platforms are doing so for the drag strip, where the engines aren't going to be driven with sustained high loads for extended periods (think DE), so cooling isn't their top priority. Conversely, the M96 crankcase is akin to swiss cheese. The clamshells that hold the cylinders are made from recycled aluminum and aren't structural - head bolts pass through them and affix to the very rigid crankshaft carrier. Anyone who has machined on one of these cases can attest to that. Likewise, when you torque the cylinder heads, you can see the top of the block move as the heads are squeezing the case halves. That's also why hardening sealants don't work on them - the case flexes and moves too much. One last example I'll throw out are Subaru engines in general. Yes, they can make serious power and still use iron liners and do fine in normal use or on the drag strip, however the engines do get thermally overloaded quite easily on track more than a few laps (and yes, I've done Nickies on Subi and other engines in the past to address thermal issues with engines originally fitted with iron liners). Throwing a dissimilar alloy with significantly lower coefficient of thermal expansion does not help the situation. Nodular iron has a CTE of 11.5 �m/m-�C whereas A390 is 18.0 �m/m-�C (@Temperature 20.0 - 100 �C). There is a reason why all Subaru engines are notorious for needing head gasket replacements before 100,000 miles. If your intention is to de-tune the engine and make less power than stock, then maybe iron liners is for you, but for most people wanting to rebuild their M96 engine, they are looking to increase displacement and add 50-100 HP to what it made previously. At least with Nickies you are getting a bump in thermal conductivity over the factory cylinders as well as an increase in strength and ductility over the factory cast in Lokasil aluminum liners that makes up for the additional heat you are producing.

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I agree wholeheartedly with this, but the M96 engine isn't an air compressor or lawn mower. It's a bit more complicated. :-) The whole idea with Nickies is to not have to bore them out. Just like the factory Nikasil cylinders on an aircooled engine, as long as something catastrophic doesn't happen, you just deglaze or worst-case do a clean up hone and just re-ring (or fit new pistons and rings in the case of an houred out race engine). Not that many engines having been fitted with Nickies have had to come apart, but the blocks we've seen have held up just fine. We did a 3.4 996 block back in 2013 for a dedicated track car that saw five years of abuse. He just pulled it apart this last summer to refresh it and sent it to us for inspection. The block was perfect - we ran it through our ultrasonic washer for the guy and he was able to just re-use it as-is.

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Agreed Charles! Mine was more a rhetorical comment on our �throw away society� in general. After doing quite a bit of reading/research (about 3 years worth) I decided to go for a FSI Stage II rebuild of my motor. I�m comfortable with the decision I made.

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I agree, but I think the cooling system can handle the slight increase. There is MUCH more cooling system loading by increasing displacement and power then there is by changing the cylinder wall from aluminum to Iron. Most of the heat transfer is done through the cylinder head (aluminum), and through the valves, and spark plug. the cylinder wall at the top is a small portion of the "combustion chamber" and should not effect the heat transfer very much. I agree, There is always a debate on whether to transfer the heat away to keep cool, or to retain the "heat/energy" to make more use of the available "heat/energy/power" rather than lose it through the cooling system or exhaust. Even most scientist can't agree . I just know that most of the heat transfer is done through the cylinder head. Like I said above, adding 50-100hp (through increased displacement) will load the cooling system much more than changing to Iron cylinders, due to more air/fuel being burned and the BTU energy has to go somewhere, some will go to power, some to the exhaust, and some to the cooling system. Since the cooling system can accommodate the extra load of 50-100hp more, it should not be a concern for Iron cylinders. The spark lead time may need to be dialed back a little for Iron cylinders, maybe not. Used be 36 degrees was the spark lead on all N/A high performance engines, we now running less than 20 degrees and making more power. Dialing back the spark lead time may not even loose power, if so a larger displacement could more than make up for it.. Like I said before LN Nickies are the best there is, but maybe the Iron cylinders are the second best, compared to Lokasil.. I believe durability is made from the head gaskets down, and horsepower is made from the head gaskets up. This has always worked for me.

I know a lot of people in here have turned their nose up at Iron Cylinders, saying things about the expansion rate, the heat transfer, the dissimilar metal corrosion, ect,but it looks like Porsche has returned to Iron Cylinders for the 992 Turbo S. I tried to speak of the merits of Iron Cylinders but it wasn't well received and didn't get much backing, but Porsche seems to agree. What say ye? �a twin-turbocharged 3.8-liter flat-six�remains largely unchanged with the exception of iron cylinder liners , cast-iron exhaust manifolds, and piezoelectric fuel injectors. https://www.caranddriver.com/reviews...rototype-ride/

Never gave a damn what they said, or what they thought.. At least not since 1997.

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Yea, I know, You don't care what us " Gold Meisters" think or say either...

Unfortunately as I read through this post it became more and more clear to me that the issues people were reporting on and had opinions about (while often technically right for most other engines) - seem to have missed the main point about the problems of fitting ferrous liners to this particular engine design and that understanding what the problem is would explain away most of the points they raised. So - if you want to find out what is the real cause of all main problems you can obtain a very lengthy and very detailed technical report (complete with photos) over the Internet from our Sharon on [email removed] (showing that every month or two we receive yet another failed block with ferrous liners to repair properly) explaining what we think the causes really are. Just ask her for the report on the 4 main weak spots in this engine range. However – for those who don’t have the time or patience to do that – can I briefly explain that the main cause of most of the problem you all either report on or defend about is that this block is cast with an open deck top of the cylinders (as shown in numerous photos) that are therefore just round alloy tubes. The first engine type (Boxsters) had thicker cast in tubes and the piston weights and thrust loads were lower – and they remained round. However as the capacity was increased there was no corresponding increase in deck heights (despite longer strokes), no increase in cylinder pitch (as bores increased - so coolant space diminished) and eventually the “tubes” were made thinner as a compromise (to find space) – while the pistons got heavier and the thrust loads increased until with the 3.4 996 they became so thin they stretched oval and cracked or “D” chunked. Boring them out to fit a dry liner reduces that thickness even more resulting in the remaining alloy tube being even less stiff than it was before and this has several implications to fitting ferrous liners. The liner thrust loads will push it against the thinner, even weaker alloy support tube remaining and will stretch it again until it become lose at the top and this allows coolant in to erode the joint, liners to slip down (and corrupt the head seal), liners to even rotate in the block. Deciding on the right interference fit is a catch 22 situation because if you leave the alloy thicker (by fitting a thinner ferrous liner) it is still weaker but the liner is so thin it crushes inwards (during cooling after fitting it) - and this minimises the designed interference fit – which when the differential expansion occurs at running temperatures can become too weak. If on the other hand you make the liner thick enough to resist crushing, the alloy tube supporting has to be bored out even bigger and is therefore even thinner and even less able to resist stretching again and on fitting it and cooling the block the outer alloy stretches – once again reducing the designed interference fit. The small cast in ring half way down that is part of the original block is the only part of the liner fit that retains it with a proper interference fit (because it is the only part joined to the rest of the block) – the rest at top and bottom is just a thin free standing tube and stretches – and if we remove a ferrous liner, the bottom of the liner will always slip into the top of the original bore – demonstrating this stretching. The reduction in the interference fit also reduces the heat transfer at the top (where it is most required). As well as the reduced heat transfer and differential expansion rates (correctly described here by others) fitting a ferrous liner to a suitable type of block is a cheaper option that can work well for many engine block types (especially for racing where running clearances never need to be right for generally driving and low power outputs and reduced heat generation) – but for an open deck alloy block with relatively think alloy tube wall thicknesses – it is never going to be a good technical solution for road cars when for most of their lives they are driven at a fraction of the potential power and the pistons are running with much less crown heat and are not fully heated up or expanded and are at a smaller diameter – increasing running clearances for most of the time in use. Cast-in iron liners avoid many of these pit falls (improving thermal expansion rates and avoiding slipping) but still need to be relatively thin and are best if the piston is smaller than 80-85mm diameter (because running clearances hot and cold increase and decrease as a proportion of the diameter), while plasma spraying onto alloy blocks is the way forward in the future. This explains most of the issues I read about above – this block design is just not suitable ideally for a ferrous dry liner. The better solution for this particular type of open deck block with thin tubular tops and bottoms of the cylinder is an alloy Nikasil plated liner/cylinder of which there are 2 solutions - a thinner alloy dry liner or a whole new thicker wet alloy cylinder (which we provide). These expand and contract with the piston heat. The inside is always hotter than the coolant at the outside – so they never loose their designed fit and tolerances and clearances remain as designed and clearances much closer throughout the full range from restricted driving to fast track use. We chose to repair these with a whole new cylinder so we could add in some improved features. Our solution has a top hat that fits into a precision machined recess at the top of the block that prevents the top of the liner from going oval, stretching or moving in the block – completely stabilising it. This cannot be done practically or easily by a machine that cuts the bore by a rotating tool (used by many reconditioning shops) but needs to be generated circumferentially (usually by a CNC machine). There is better heat transfer and modulus (stiffness) from one solid cylinder than two tubes fitted inside each other (tubes inside each other are a way to render a construction more flexible not less). We added to the heat transfer by including ribs to increase surface area in the block because it has less coolant depth than previous engines or later (Gen 2) ones. Our solution is technically similar to the GT3 or Turbo version (which are also a solid alloy Nikasil plated liner in a closed deck construction) which despite more power and heat never give any significant cylinder problems. For our oversized engine conversions we also fit a support ring into the bottom of the cylinder to fully support the cylinder top, middle and bottom (and this can be seen in photos of our oversized engine conversion technical report also available from Sharon – warning – again long and detailed and not for the faint hearted). A failed ferrous liner may have been fitted with a bigger bore than a dry replacement alloy liner is made to but with our solution there is also no need to send blocks to the scrap yard just because the ferrous liner failed or the hole was bored to big for an alloy replacement - because we machine out the whole of the original support alloy anyway – so “D” chunked and cracked liners can still be repaired by us even if they have failed. The later engines (Cayman S, 996 3.6 and 997’s) changed the quantity and size of the silicon particles in the Lokasil tubes cast into the blocks (that made the cylinders stiffer and reduced stretching and eliminated “D” chunking) but also created a secondary problem because at the same time plastic coated pistons were introduced and the larger silicon particles involved caused more cylinder bore damage when they became lose and ran momentarily between the piston face under load and the cylinder bore – eventually wearing into the plastic coating or wearing it away. It must be difficult for owners to know who to believe and what to choose to do when they have problems when these issues (and quite a number of others) we often find are misunderstood (even by experts). Our reports that I referred to earlier can help to expose and explain what the result of our own research has concluded and enable owners to at least consider alternatives without preventing them making whichever choices they prefer. Knowledge is power and we try to increase general knowledge by providing these highly tested and researched reports without openly trying to upset too many contributors. At the end of the day – there are always alternatives. Some might work just as well, some might be adequate and cheaper, some will inevitably fail when the owner has been mislead (and are often not even cheaper) and eventually the reliability of different solutions and providers feeds back into the system and becomes common knowledge – so researching what others find from different solutions is beneficial. However can I respectfully make this point. I am surprised how few providers who repeatedly build engines that we have to repair again afterwards - are reported about/ The public seem often to be lambs to the slaughter with some providers. I guess if a specialist only ever applies a few solutions to rebuilds – you may never hear about it if they fail, but if a provider supplies the majority of the market and you either don’t hear anything bad or even some good reports – then they must be doing something right. To my knowledge there are 3 suppliers Internationally that repair a lot of engines with good results (either alloy Nikasil plated alloy replacements or ferrous ones for racing undergoing much reduced mileages) and a hell of a lot providing small numbers and with much higher failure rates (in contrast - we are approaching 3000 liners without failure). When the original manufacturer gets something like this wrong (or particular failures are common enough for independent specialists to try and help provide a better solution) the reasons and causes will always be very hard to identify and solve (the original manufacturers are not stupid) and the independents that try and help have their investment, pride and income at stake and this adds an element of doubt in whatever anyone says that must make decision making by someone with a problem - very difficult indeed to choose between. We are not telling anyone what they should do, but just reporting the results of our investigations and the technical reasons why we prefer our own solutions. We do so because we see a lot of rubbish reported and a lot of failures that are not reported and feel the public deserve better explanations and a higher technical level of reporting – what they do about it we are happy to leave to them. It would be nice if others that report contrary explanations also provided similar levels of technical engineering research, back up and reporting rather than the thin levels that propagate so many forums these days. Baz

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You are in the UK, does anyone in the USA install that? And blocks that have been in service; can the surface of cylinders be refinished and overall shape rerounded? The top hat addresses ovalization, and how is bore scoring solved?

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They aren't using cast iron liners. Porsche has replaced Nikasil with SUMEbore. It's a metal matrix composite that gets super-heated and sprayed at the bore, bonding to the aluminum substrate. They first used it on the 918 Spyder. The SUMEbore coating is about .004-.005" thick after honing and does not provide a barrier to heat transfer. The block is still all-aluminum and retains the same thermal properties of an aluminum block with Nikasil. Jake wanted to try something new and we're doing aircooled Nickies with SUMEbore F2071 coating as well as an M96 engine to evaluate the process for special projects. It's over four times the cost of having cylinders Nikasil plated, so the market won't bare it, but it's important to continue research and development.

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Seems to me they've made some pretty poor engineering decisions in the name of cost savings before... Time will tell

Hmmmm...evidently no cost savings for this SUMEbore (iron)... ?

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In volume, yes. Oerlikon sells the equipment and powders to the OEMs to implement in their production lines. SUMEbore is an environmentally friendly process too, helping appease the greenies. Ford and Nissan, among others, utilize SUMEbore. Ford with Ford GT 350 and Nissan GT-R. But basically only high end applications. They have been using it in Nascar for years.

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^^ The plot thickens...

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Baz, thank you for your detailed technical responce. I have followed some of your technical thoughts and know you have very good solutions to the issues of the M96 engines. But I think you haven't read through these posts carefully, even though there have been many comments on Iron "dry sleeve" process, what I and others have been advocating for is complete "iron "wet" sleeve" process. That's what it is called over here, y'all may have a different technical term for it over there, but it's a complete cylinder and actually not a "sleeve". Yes, I realize it is less efficient, but it is more stable and more cost effective.

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Charles, I believe you.. Thankx I can see them using Plasma Wire Transfer (PWT) and a MMC of Iron to coat the cylinder and calling it by the Brand name SUMEbore, but that process has been out for almost a decade. The Porsche Technical Information department is who put out the info to the magazines, if that's the case should have said PWT process, or SUMEbore coating instead of "iron cylinder liners",. Seems ironic that they get "piezoelectric fuel injectors" right, but fumble the ball on "iron cylinder liners" Someone needs to straighten them out over on the 997 forum also. https://rennlist.com/forums/997-foru...992-turbo.html https://www.google.com/url?sa=t&rct=...7uJpI9b2u1TCT4 https://www.google.com/url?sa=t&rct=...iSrn1KQdMVtCtM

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I agree... No cost savings= Not interested !!!

So much for operational security... Great, now we have to hear gold level opinions, along with the developmental challenges. Awesome.

Hi 996.2 – we have had many International enquiries for our cylinders to be sold separately - but the success of them comes from fitting them correctly and that was something we didn’t risk being done by sub-contractors over here in the UK. Instead we bought in expensive new machinery and manufactured our own jigs and fixtures and even all the special tooling – so we could run the operation continuously “IN HOUSE” with aerospace level quality controls (some of which can be seen in our 2 videos on our web-site www.hartech.org ). This also reduces down time (no transporting of blocks to sub-contractors and no waiting for their machine availability). What we do and provide should be by far the most expensive because it uses the highest quality materials and involves more machining than fitting conventional dry or wet liners, the new cylinders are manufactured for us by a highly regarded F1 supplier and they also provide the pistons for our oversized engine range. By having a slick organisation that does nothing else – with staff trained to do those jobs day in and day out – and by not having each sub-contractor adding in their profits – we manage to provide a superb quality for prices often no different to less high quality ferrous liners provisions and only a little more than some others. We also discount for numbers of cylinders from one only up to one block and all 6 and they are all available with the top secured in place (including fitting support rings to the tops of Lokasil bores on bank 1 for customers who cannot afford the whole job). It is of course expensive to send heavy blocks to the UK and so when Alpine Autowerks in Canada expressed interest we agreed to allow them to fit themselves and followed a training program in the UK and with us over there and also have their own IN HOUSE machinery and so we do supply to them – but their market is relatively small. So far no USA business is prepared to reproduce our quality systems but we do re-manufacture blocks for specialists from all over the World and have special exclusivity arrangements in some Countries where blocks are moved in secure boxes back and forth – all working well and with no problems. However there do seem to be other alternative provisions in the USA that are working OK and we are so busy anyway we are not trying to enter that market – we are just trying to point out some rather obvious technical issues and miss information on forums that might help owners anywhere to avoid making mistakes and choosing the best options locally. We also have some donor blocks for exchange but are running out of 3.8 blocks now with 3.6 blocks getting lower. Porschtek 3 – thank you for your points and there is a significant difference between a dry and wet liner replacement (as expressed in my previous posts). With a high interference fit of a wet ferrous liner you are relying on the relatively thin ring about half way down the block to prevent the liner tilting against the thrust loads. This can be stable with a high interference fit but then you are relying on the greater height from that shelf to the top to hold the liner vertically against side thrust loads that are maximum very near to TDC and that height and differences in the expansion and contraction mean that when the engine is hot the head gasket clearances increase to the liner. Unless a different head gasket is used the tri-metal thin std gaskets can gradually suffer sealing against that movement. I would agree that at least a wet ferrous liner avoids another problem that is common with ferrous dry liners - when fitting them with high interference fits - the block has to be much hotter than running temperatures and on shrinking can suspend the liner off the shoulder and allow it to slip down in use over a period of time. All used blocks have the tops distorted by thermal stress relieving and need re-machining flat and it is essential that any liner or cylinder is properly set on its base shoulder before that to avoid shrinking down. Although we have plenty of experience of wet and dry ferrous liners that have failed – it is only fair to admit that we have no personal experience of how long a properly fitted ferrous liner can last (and our report has pictures showing that we have had to replace several ferrous liners in the UK that have moved or slipped) but that doesn’t mean it cannot be done reliably by others. However I cannot understand why no one else seems to provide a precision machined location at the top (as we do) because this at least makes the liner more stable (perhaps some do that I have missed). I accept that in a ferrous liner this would need a thicker liner tube to start with and more machining to create the large enough top hat (i.e. more expensive) and that it involves more machining in the block (that not every sub-contractor can manage accurately enough) and would be even more expensive – and in the end little different to the cost of much superior alloy Nikasil cylinders that improve piston clearances at all temperatures and operating conditions and are virtually indestructible. An unsupported ferrous liner (wet or dry) should be cheaper (but worth comparing with alloy alternatives). We are confident that we could fit a ferrous liner securely enough but having decided from day one that the only right way to do things is with alloy wet cylinders and having invested in a continuous production facility to make those prices really competitive - with their fantastic success rate over 15 years – we would not have any reason to consider trying it. It has taken a lot of research and development, testing and trying different things over many years to get to the bottom of why cylinders scored etc – but the choice of these Nikasil plated alloy wet closed deck liners was never under any question from day one and is indisputably the best proven solution available. I do hope a few brave engineers and specialists will request our reports on the 4 main weaknesses and also on our oversized engines – so they might feed back into the Internet just how much we have put into what we do and why – although I appreciate they are a very long and detailed read – probably best spread over several days (sorry). With so many different suppliers trying to sell different solutions and explanations trying to justify their choices flooding the Internet – it is impossible to deliver a report that does not cover all the other areas that people claim are causes and work through them in detail – that ends up being short and sweet. We also reveal how we got side-tracked sometimes at the start of a particular investigation and made some wrong assumptions – so we are not trying to make out we can do no wrong. What it should demonstrate though is that we pursue the truth until we find it and that a thorough look at as many alternatives as possible can enable a clear answer to emerge that fits all scenarios and therefore at least has merit that should help others make more informed choices (even if that is not from us). Baz (Barry Hart Technical Director Hartech Automotive UK)

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Correct, the cost to OEM's is very low due to the volume, but they still will compare a few dollars, or even dimes... This exert from an OEM cost engineer , "But Mr. Wuest says two aspects currently mitigate against spray coating. "From what I've seen, it's cost - and the fact that it's a relatively new technology," he admits. There's plenty of industry dissension about the true cost of spray coating, but Mr. Wuest is frank with his figures: He reckons iron liners cost about $1.50 to $2 per bore; plasma coating probably ranges from $3 to $5 per bore. Meanwhile, Nikasil runs from $5 to $10 per bore, the cost largely dependent on volume. Alusil and Lokasil cost even more ."

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No whining all over my thread.

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Hi Baz, thank you again for another very thoughtful and detailed technical responce. but that doesn’t mean it cannot be done reliably by others. However I cannot understand why no one else seems to provide a precision machined location at the top (as we do) because this at least makes the liner more stable (perhaps some do that I have missed). There are in fact at least one US supplier who is doing "complete Ductile Iron WET Cylinders with closed deck", and I have just learned of possible another. I do have your very large detailed report, and I admittedly haven't read it entirely, but have read a good portion, and have it stored on my computer to reference. Also your prices are very reasonable, I hope you don't mind I have posted your engine build services in my "under 10k DIY engine thread" with US dollars conversion for comparison, If you have any objections, I will remove it..I know you have a Canadian partner, but I don't know if the price structure is the same. Again thank you. .

E-mailed Sharon for technical reports and photos. If I understand correctly there are two ways to fix cylinder issues in 996s; at high cost machine out existing cylinders and install new ones usually Nikasil plated wet alloy, or the much lower cost machine around top of existing cylinders and install a metal top hat support and reround factory coated cylinder. If that second method exists many owners need to learn about it. New Nikasil cylinders would give 100k+ miles of service life, and supporting and rerounding existing cylinders would be expected to provide how many miles of service? Thanks very much Messrs. Hart and Raby for information already provided.

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The second method you referred to in your post does still exist according to Harttechs website, if your cylinders are still in good shape, just ovaled and not scored.. I like this method as it's very cost effective and would provide many years of good service. You will like the in-dept report from Hartech if you enjoy very detailed technical info and have a mechanical mind.

Thank you for your generous spirited response Porschtek3 - many competitors just use this medium to discredit others and so it's appreciated. I hope you eventually manage to flog through our report completely - it explains why bank 2 fails first, why bores distort, what actually causes bore scoring etc. I hope those that believe some other's explanations connected to components on both banks or piston pin offsets on different models - will be able to use the actual facts revealed to see how misleading such apparent gems of technology are and question why they are wrong! We do still fit support rings to Lokasil bores. It is a difficult position because it will not stop bore scoring (although restricting bore ovality will help maintain a better load spread over the piston face). In our experience bank 1 bores last about twice as ;long as bank 2 but those that have seen the pictures in our report of different modes of piston coating wear will understand that the variable rate of silicon particle loss rubbing against the piston can wear the coating away, or the bonding becomes unstuck and pieces just float off and so predicting exactly how long any one cylinder might last is impossible - too many variables in piston coating and silicon distribution and bonding to reliably predict - so we can only provide guidance from averages and experience. Some owners simply cannot afford a full 6 cylinder rebuild and this places us in a dilemma. if we insist on only rebuilding with 6 new cylinders we encourage a lot of impecunious owners to go elsewhere and get a cheaper job that will on average not last very long (and most who do actually sell the car and pass the next rebuild onto the next owner). A reasonable economy rebuild is 3 cylinders on bank 2 and support rings on bank 1 and we feel we help owners in different financial circumstances by offering these options - but try to encourage as many as possible to do the job fully (with discount incentives). Some who had support rings several years ago and had reliability since but eventually had a bank 1 score have then had a second rebuild when they can by then afford it as a result of thousands more miles of relatively cheap motoring. It would be nice to insist on all 6 but our provisions have proven a better stop gap than the many ferrous liners that have come back to us to be done again. A lot of these returns are because the individual reconditioning providers see few similar engine types and just fit the liners like they would in a stronger closed deck - not understanding (or being concerned) that they are just not suitable. We have never disouted the quality of the liners supplied to the market nor that they could be fitted better in many cases than the ones we see (obviously any that have been done reliably we will not see for a second rebuild). We have seen (and replaced) some with big top hats but found the block was not actually machined and they were just there for show with a small clearance?. Properly done it at least stabilises the liner radially. We are happy to repair export blocks for specialists Worldwide (I think the latest is 53 Countries we have successfully supplied) and turn them round quite quickly. We also have trade relationships with some others. The risk we took to anticipate large numbers (for us) at the outset and invest in a flow production layout means we have several employees continuously rebuilding and remanufacturing these engines and as a result our prices reflect that efficiency. We thought about the issues of allowing others abroad to fit our cylinders under licence and the price structures they would have to work with - but we decided we could not impose our price structure on agents abroad who have much smaller turnovers, different internal wage and industrial cost bases and who could not match our prices viably. However - the resulting prices are probably little different when you take into account transportation of a whole engine or crankcases over the pond! For racing - ferrous top hat liners should provide a reasonable alternative (because the conditions for clearances etc are repeated and oil consumption is not an issue) although most of the two main Porsche production Championships, races and events in the last 5 years have been won with engines we built over here. One problem we do experience has been the variability of the Porsche Mahle piston sizes we receive when we have to replace pistons (rather than re-coat them) that can be as much as 0.025mm (one thou) requiring us to re-hone bores after assembly to match clearances (and this provides a problem exporting blocks to use with customer pistons from abroad - matching sizes without having the pistons to measure ourselves) but we are now not only receiving matched cylinders and pistons from our UK provider for our oversized engines but also for standard rebuilds to make up Block and piston packages (with other parts like the IMS shafts etc) that should be easily handled anywhere. With conversions from 3.2 Boxster and 3.4 996 to 3.7, 3.4 Cayman S to 3.7 or 3.9 and 996/7 3.6 and 3.8 to 3.9 as well as standard rebuilds we are always running flat out. The 4.0 Gen 2 is testing well (although we are now rebuilding it replacing the first 3.6 heads with the 3.8 heads with larger valves) and have other developments to follow along in the future - so combining that with standard rebuilds - life is pretty full on over here. Thank goodness we decided to do a proper job of all this so many years ago now - because it would make no commercial sense now that we have invested and serviced such a large proportion of the market - for anyone else to try and reproduce the same level of provision to only share the market with us afterwards (and then prices for both provisions would have to increase anyway). It was our engineering assessment of (and confidence in our predictions for) the weaknesses in these engines over 15 years ago that encouraged us to take a huge commercial risk and we were lucky that we got it right and now benefit both us and our customers that such a reliable set of top level solutions is available at such very reasonable prices. Baz .

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Everyone expects at least 100k miles out of a rebuilt street engine, and as of today to ensure that from a M96 requires original Porsche cylinders milled out and Nikasil ones installed. New Porsche short blocks, support rings on original Lokasil cylinders, steel cylinders with eventual sealing issue at head and poor heat transfer and possible slipping/rotating; apparently as of now none give a high confidence of reaching at least 100k miles. If someone developed a Nikasil liner that could be installed by the neighborhood machine shop that just milled blocks .030 over, they would sell a lot of them.

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That was developed more than 16 years ago. The issue is, the OE parent material is too weak. An underlying crack that forms in this parent material is a game- ender. Cut corners on this stuff to make it faster/ easier/ cheaper, and you are wasting your life with the effort.

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Hi Jake, I just noticed you don't have any "likes" so I gave you one. I hope this is not the highlight of your day,, Semper fidelis !

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Wow. Thanks dude. It would be especially helpful if I could gain a new "follower" too... Follower.... Damn. If you follow me, you'll see lots of things you don't want to see!

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We could easily accommodate this in stock bore sizes especially as we already o-ring the blocks, but I'll be honest that I don't trust a general machine shop to do it right. We have specialized tools and processes that would have to be duplicated by the installer including all the post QC checks to ensure it's perfect. Haste makes waste. But if you can't wait for us to turn around your block, we have already completed blocks available on exchange in stock and big bore configurations: https://lnengineering.com/rnd-store/...cks-cases.html We won't do anything to our process that will sacrifice quality.

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For the record, the SUMEbore cost me over $400 a cylinder and that was without any finishing. Just coating. Economies of scale :-)

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I haven't seen the Porsche 992 Intro Book, so I can't validate this or not. My presumption is that Porsche would use SUMEbore like they are doing in production of the 718, which according to Porsche was to cope with poor fuel quality (which can contribute to failure of the Al-Si cylinder bore system in Lokasil and Alusil engines). However, if they did use cast iron liners, it's going to be a dry liner configuration like in a Subaru engine and I'm sure they would have designed the engine and it's cooling system to accommodate this configuration.

Charles - agree absolutely that it could be dangerous to let liners/cylinders out for "any old" machine shop to fit - looks like you have a great range available over there. I noticed that all the photos on your web site appeared to be from the bottom of the blocks - just interested - are yours wet cylijnders or dry liners and do they close the deck at the top? Baz

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I posted earlier in the thread a picture of our open deck wet sleeve process, only with SUMEbore shown. Same process is used for our Nikasil sleeves. I have processes that were developed exclusively for Jake for open deck 103 and larger bore 4.3+ builds as well as closed deck for high boost applications that are proprietary to him, but there are public videos and photos of our standard processes available on Facebook.

So you have Charles - lots of open deck pictures (didn't have time to read through it all - sorry). We believe the cracks we see in the outer cast machined out block when a ferrous liner has been fitted are the result of the liner itself being stiff and strong enough not to crack but the piston forces pushing it against and even thinner and weaker out sleeve then stretch the sleeve opening up a gap for corrosion and eventual cracking. This conclusion came from removing many ferrous liners before the outer has cracked (but when it has stretched bigger than the liner and no longer had an interference fit at the top) and others where a faint crack has started - and always (like in the photo) generally in the main thrust area and side. This is why if a ferrous liner is to be fitted we think it probably would benefit from a closed deck top hat. Just to clarify - in the UK we refer to a wet sleeve/liner or cylinder as meaning the outside is in contact with the coolant (so no remaining sleeve from the original casting tube remains). I presume this means dry liners cannot extend the bore capacity by very much (if anything) or the original remaining outer alloy cylinder sleeve would become even thinner and less able to restrain the liner reliably in place. The original open deck design was not because it had any technical benefits but because it was necessary to cast the Lokasil preforms under such huge casting pressures that sand cores could not be relied upon and the moulds had to be strong enough to be extracted with taper rather than broken up and washed out (as with sand cores). I suppose an alloy dry liner would have one benefit over a ferrous one by expanding with the block and in so doing maintaining a tighter squeeze against the head gasket - which in turn could help stabilise it? An alloy dry Nikasil liner would be much cheaper to manufacture than a thicker wet one from tube thick enough to create a top hat to fit the block (the former being made from a smaller tube with simpler machining) and much cheaper to bore out the block to fit it to - but we have always manufactured complete replacement cylinders with the benefit of increasing the external surface cooling area (through ribbing the O/D) better heat transfer from no inner mating joint faces and locating the top in a precision machined recess to stabilise the whole cylinder and prevent any movement or ovality - so have no experience of dry alloy liners. With no interference fits needed for a solid cylinder at the top there are also stability benefits during thermal expansion and contraction. We made up for the extra cost by machining everything IN HOUSE. I presume bigger bore versions either have ferrous liners or steel ones (that could of course be Nikasil plated) with some closed deck top? Re-plating onto the original casting bore (after boring out) is also available over here but although the later blocks have stiffer alloy - we find the cylinder tubes still expand oval over time and so have stuck to our original (and it seems fool proof) solutions. However there seem to be plenty of options available over in the USA and it seems from the lack of complaints that they are all working satisfactorily? Not so in the UK for some reason? Baz

We do not do any dry aluminum liners other than for 9A1 or Cayenne where there is sufficient scoring to require the block to be overbored and fitted with one or more repair sleeves. All our sleeves are aluminum, even in excess of 103mm and open deck.

While a lot of my most advanced engines have a closed deck option with Nickies, it's not necessary. This is from direct experience, running over 14:1 CR on N/A engines, as well as engines with forced induction. The Nickies material stays straight, and remains very strong, even when purposely over- stressed. I have some engines with more than a decade of track service, running open decks on a 101mm bore, at 14.3:1 CR static. I don't consider closing the deck until we arrive at my R43 engine, and make 460HP on pump gas, as a starting point. Even then I nay do it because it is part of a system that I developed that even requires the use of longer timing chains.

I read entire detailed Hartech technical report on M96/7 failures and solutions. Some info goes against what a number believe about these engines. Could write a summary but signed non-disclosure agreement.

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You could ask 20 engine builders the same question, and get 21 different answers. It�s been this way since the beginning of time, and exists with Chevy builders, to Porsche engines, and everything in between. The engines we create end up with our character, and share that all over the planet. At the end of the day, none of us are wrong. We all create what we believe in, and for the best of us, what we do works. The imitators don�t count- they just follow the leaders. They don�t have the ***** to do anything their own way, so they never learn.

996.2 - you are very welcome to write that summary, E-mail it to me and I am sure I will be able to approve it for general posting. It was not our intention to limit discussion but to prevent others copying our intellectual property for their own benefit after we put in the time and money to research and to test it all out. I would welcome discussions on some of the content and see how other experts relate it to other provisions and read the more technical support others may have to substantiate their own claims. What I didn't want to generate was bitchy arguments from competitors that goes off the subject matter and deteriorates away from it. The topic of what causes bore scoring is particularly relevant to this whole subject. There are often different solutions that work perfectly well and I have always said that it isn't necessary for a supplier to even understand the causes of a fault in order to provide a solution that works. As long as their solution is reliable it wouldn't really matter if they came to that decision for all the wrong technical reasons - as long as it works for their customers. For example if they didn't understand what causes bore scoring but decided to change the cylinders or piston coatings and it worked - it doesn't matter if they don't know why or even if they think the original cause was something else that turned out to be wrong - as long as their solution solved the problem. The difficulty we have is when technical explanations are posted to try and encourage owners to follow a particular solution rather than an alternative - when the explanation is technically wrong - as this can lead others up the garden path. I find this particularly wrong when specialists are trying to promote their own solution with a technical explanation that we have proven wrong that then discredits those providing the right answers. This is perhaps behind the disastrous situation in the UK when many owners have to have their engines rebuilt for the second time because they chose a solution or provider that didn't do a good enough job the first time. This report is just an accurate and true description of all the work we have done on the subject for the benefit of owners and specialists who want to find out more and for their own personal benefit and knowledge. If anyone disagrees with the findings then that is absolutely fine by me - as long as they have had the opportunity to relate it to those alternative explanations and come up with their own conclusions about which to believe. What we find wrong is to sit back in the knowledge that often repeated explanations are in our opinion misleading or wrong while the general population are beginning to accept them as the norm and repeat and support them to everyone else. Just because one explanation is more accurate than another doesn't always make the conclusion wrong, and anyway - as long as the alternative providers solutions work well enough and for long enough to satisfy their customers - that is the main thing. It may very well be that our British way of handling this is not as well received in different Countries as our own or even by all of us over here - and that is why we requested the non-disclosure agreement in the first place to put off trolls and those wishing from the very outset to simply exploit the content for their own commercial benefit or to try and discredit ours. So - to clarify - it was intended to inform readers for their own personal benefit - but that does not mean we are not prepared to allow the content to stand up to the scrutiny of others in a public forum as long as it is for the right reasons - getting to the truth. Baz

Working on summary will let you know when emailed to Sharon.

Received a summary and Sharon will be contacting you shortly - no problem. The reason we provided such a detailed alternative version is because a short summary - while accurate - doesn't provide sufficient evidence to convince sceptical readers that there is any reason to take any more notice of those conclusions than other conflicting ones and therefore would only persuade readers of the value of the research that created the results if they could read more, compare the technical findings and follow the sequence of events that enabled the right conclusions to be reached and that the science and technology included supported. Your review would be entirely sufficient IF readers believed it - but competition from rivals leaves most readers unable to make decisions when solutions disagree and our long version is our attempt to provide enough evidence to persuade readers across a wide range of engineering and technical ability to enable them to be better informed. Thanks for your interest by the way - much appreciated. Baz

Summary of main problems and best solutions for Porsche M96/7 engines in a report written by Hartech Automotive technical director Barry Hart. Contains information that is likely many have not previously seen. IMS BEARING catastrophic failure affects 2.5, 2.7, 3.2, 3.4, and 3.6 litre engines. Original bearing too small with marginal load rating, subject to dynamic lateral loads from chain whip, and tight fit in housing leads to distortion of thin outer race and rapid wear. Some original bearings survive because race and ***** have space for wear particles to migrate out and oil to seep in. Many failures in replacement bearing types using original shaft housing including rollers and those with ceramic ***** due to tight fit, distortion during installation and removal, and fretting in shaft housing. Mitigation – If original bearing has survived 80k miles can leave in place and may have greater time before failure than replacements that use original shaft housing. Solutions – Install plain bearing with oil feed (expensive). During engine tear down remanufacture IMS to fit later and larger Porsche bearing (remove seal) which has load capacity and shell strength to last indefinitely. CYLINDER CRACKING AND D-CHUNKING 3.4 engines. Displacement increase from 3.2 led to cylinders too thin, and only supported near middle and not at top or bottom, eventually cylinder becomes oval and cracks in a straight line or curve with a piece breaking off. Later larger displacement engines didn’t have this problem because cast with different and stronger formulation of Lokasil material. Many failures in replacement liners including ferrous iron due to rotation/slippage and seal failing at head gasket. Mitigation – Support rings can be installed at top of original cylinders to keep from going oval, but these cylinders eventually fail also. Solution – Machine out entire old cylinder and install Nikasil plated aluminum one. Replacement can be “open deck” where still held only in middle, “closed deck” additional support at top, or closed deck with ring added to bottom for support at top, middle, and bottom. CYLINDER SCORING 3.4, 3.6, and 3.8 engines. Material Porsche used to line cylinders (Lokasil) contains many particles of very hard silicone embedded in aluminum. Piston rings eventually dislodge pieces of silicone which wedges between piston and wall. Earlier pistons were coated with hard iron and silicone fleck harmlessly washes into oil and is filtered. Due to environmental regulations iron coating was no longer applied but instead pistons coated with plastic that silicone bits embed into and ride up and down cylinder scoring it. More particles are shed off walls and process accelerates over thousands of miles until oil consumption rises and noise is heard. Rod to stroke ratio and piston pin offset not factors in scoring. Mitigation – Install lower temperature thermostat, use thicker film oil, warm-up before driving hard, don’t lug engine, rev higher, drive vehicle regularly. If originally had good silicone particle distribution and follow recommendations engine can reach 200k miles before scoring, otherwise can score at 15k miles. Solution – Same as cylinder cracking machine out entire old cylinder and install Nikasil plated aluminum ones. Porsche provided no assistance in solving this problem and continued to sell the product. Summary by Daniel Lee. If summary misses or misstates a significant point in original report please inform Daniel and he will correct. Full report including evidentiary pictures available by contacting Hartech.org at [email removed] .

Quotes source post: 16282961

Mr. Hart, while I've had much respect and appreciation for your contributions to the Porsche community, I personally think you're doing yourself and others a disservice by requiring approval to write a review of your technical writings. This is not plagiarism or intellectual property fraud. It's simply a review and summary of your personal findings. If a person tried to sell the information as his own, then you would have a leg to stand on legally, but you don't. I've worked in the academic world all my life and personally, your technical article wouldn't conjure up an ounce of merit within a Research 1 institution. Why? Because you're biased Barry. Simply put, you're biased. This article reads more like promotional material for "Hartech Automotive" than anything else. The fact that you start a technical article with a self gratifying statement about your company proves that point. I don't have a problem with you personally or your desire to share your knowledge, but when you present yourself as a "King of the Porsche World" requiring that everyone bow to your approval and kiss your hartech ring just to write a critique or summary of your findings, is wrong. It seems to me that you like to write long responses to impress more than educate. Mind you, I understand the need for an exhaustive explanation of a serious problem, but it seems you have to maintain a sense of respect through circuitousness which is common trait among many of my colleagues that like have power over their students. No need to pound the gavel of respect and validity through unnecessary control tactics.

Since this thread has devolved into circlejerking , chest thumping, cheer-leading , of which is against forum policy,and no new technical discussion of the original topic of " New Mahle Pistons for Iron Bores" this thread will be closed. If new information on original topis becomes available I may reopen.