Bore scoring: 3.4 vs 3.6 ?

Good afternoon, After some reading, I am wondering which engine is more prone to bore scoring / D-chunking: 3.4 or 3.6? It seems there are more thread about 3.4 rebuilt for this issue than for 3.6 Am I mistaken? Is it just because we have more data? (3.4 are older and have more miles) It will be nice to have some comments from people who had this issue with details about version, mileage, location (hot/cold weather), etc.

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Watch the Focus on Bore Scoring video series on Rennvision. Lots of answers there. I think D-chunk is more prevalent on 3.4's but don't quote me. Do some research here lots of info on both failure modes. Mine: 2005 996 C4S 3.6, 54k miles, midwest(car spent it's first 9 years in Houston area) so both hot and cold. Not driven in cold weather after I bought in mid 2014. Late 2018 determined bore scoring #5 and #6 cylinders. Note weather is not necessarily the prime factor in determining the incidence of bore scoring(refer to video series referred to above) #6 cylinder

Bore scoring occurs because your car is running with dirty oil. When the oil film gets thinner(running too hot, cold start etc) than the debris size inside it you get metal-debris-metal contact and scoring. D-chunk is an effect of overheating the material causing hardening and eventually failure. Change oil frequent, run OEM air/oil filter (read up how the AOS works and you will get an ah-ha moment why this is important) and make sure the cooling system works well. With all that sorted there is no elevated risk for either engine. There might have been quality issues from factory but it's nothing to protect agains that...except maybe a high milage car.

Thanks for info. I am watching Jake's series on Bore Scoring which is available on Amazon Prime. Lot of information there ! Basically the weather or the mileage does not have real influence here and it is hard to detect. If I have understood correctly, Bore scoring should be detectable by: oil consumption and/or ticking noise but it is already too late trace of fuel and/or n on- ferrous (non- magnetic) shiny aluminum in an oil analysis (for example Blackstone)

There is only one way to really identify bore scoring and that is to put a camera down the spark plug hole and check. Not too hard or complicated. Oil analysis is interesting for the stuff you can't see, like main bearings.

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Many more contributing factors than just these...

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There is a lot of theories(good and bad once) but they fail to explain why the majority of cars have no issues with bore scoring.

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If you see bore scoring from the plug side, it's already serious. The best place to look for early signs are from inside the engine, under the pistons. Bank #2 is typically where this starts and is, actually, the only side you can get a scope into. Jake covers this in some of the videos.

M96 3.4 engines have the thinnest, weakest cylinder walls of any water cooled Porsche engine so they are prone to failure. I would not own one of these engines without LN Nickie's billet alloy 99mm sleeves.

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There are examples of cars which have been driven +300k miles (hard), no issue. Lots of these cars have extensive track time, no issues. If you don't maintain the car accordingly stuff will break, like cylinders and IMSB. There is nothing wrong with the cylinders. Nikasil works for track driving, not so good for regular road driving, why most manufacturer stop using it in the late 90's early 00's.

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From Jake's video: the bore scoring comes from the bottom up. Once it is visible through the spark plug it is already really advance. That's why I was thinking about the oil analysis: fuel trace could be one indication.

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Oh, so it was not a matter of cost/ environmental concerns? Not sure where these ideas come from.

Here for example: https://buy.motorious.com/articles/f...jaguar-xk8-xkr Nikasil do not like sulphuric acid, which you get with short journeys(not enough engine temp to avoid moisture) and sulphuric fuel. It is less of an issue now days when sulphur content of fuel is regulated but it still happens if you don't get enough heat in the engine. BMW have some history of Nikasil failure also, google. EDIT: on top of that it's environmentally not that good. And, racing fuel is usually of higher quality and racing is done with HOT engines.

this guy nick really has some interesting ideas. His basis for them is poor of course, but hey, I guess anyone can be an expert. that damn dirty oil causing all these problems.

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oh come on, that was an issue for like 2 model years 25 years ago. Nikasil has been used successfully for at least a decade there after.

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Insert the internet argument and wrestling with a pig joke here...

Nikasil works great in air cooled engines since they run hotter. In a water cooled there are better alternatives for general use....and that's why it's 25 years ago since most stop using Nikasil. I encourage to read up on the subject BUT exclude ALL information which are in regard to Porsche cars since that information usually comes from just a handfull people that also sell Nikasil product/service....

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Jean Luc!

I give up.... can someone hand me the cool aid?

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I have 50K+ road miles on my LN 99mm Nikasil Sleeves installed in 2010.

I think the best thing to do is just assume that any of the faults these engines have could happen to you. Regardless if one engine might have a lesser chance, it's still a chance.

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You are correct. Scoring starts at the bottom of the bore and as it gets worse, works its way up. You are also right about the oil analysis. It can be an indicator, but not totally conclusive. If there are no issues with injectors or other fuel/air problems, then fuel in the oil may point to bore scoring. There are other possibilities, or course. For example, the bore can wear or otherwise become out-of-round and permit fuel into the sump. Excessively long idle periods may also contribute to this. I do agree for the most part, continuous oil testing is one of the best methods of monitoring engine health.

So it is basically just don't let the car idle, frequent oil changes and hope for the best. It's sounds like other than those, its sort of out of our hands so why sweat it. Well unless you want to drop 25k and replace the cylinders and whatever else (most of us can't do this ourselves).

I agree! I ordered couple of BlackStone containers in advance and keep them handy for when I take my car for service. I have an 02 C2 with 102k miles which works like a champ: no oil consumption, no leak, no smoke of any kinds etc. I am in Florida and can use it all year long. But by reading threats after threats of 996 blowing up you can start to get your head spinning. I should start a threat about HERO stories, those 996s working great with high miles which haven't exploded and financially ruins their owners.

I should start a threat about HERO stories, those 996s working great with high miles which haven't exploded and financially ruins their owners.[/QUOTE] Do it! 2002 C4S here with 75,600 miles, so far (knock on particle board) so good.

One of the top takeaways from Jake's bore scoring series is to replace the injectors and I just did that on my 3.4 engine. Testing is not enough, because they can have weaker spray patterns when hot and testing will not reveal these.

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"Make it so..."

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Nice try. Incorrect. Nikisil went to the wayside only because of the extreme cost that was experienced suddenly when environmental concerns made the plating process become much more expensive. The Nikisil process requires 21 different processes of acids, and rinses, and all of that product has to be disposed of as hazardous material. Think about what you see today that's chrome plated, or has any sort of plating applied. Try to find a shop to restore chrome bumpers, door handles, or etc. Usually you'll find one, or maybe two places per state that will still do this, and some states have zero. In the old days every town had a decent plating shop. I had to send items for a truck I restoring 4 states away to find a plating shop, as an example of a first hand experience. This is the same process, and concerns that Nikisil has, and it is THE reason why it was only used with the GT/ Turbo engines, where the cost was justified, and the performance was expected. The environmental protection laws in Germany preceded what the EPA imposed here in the USA, and they remain much more harsh. People forget that the GT2/ GT3 and Turbo kept their FACTORY Nikisil cylinders in the water-cooled years to a minimum of 2011, when the first of them went to alusil. I have NEVER seen a GT2/GT3, or Turbo engine with Nikisil cylinders suffer from bore scoring, and we've also never even had a report of it from anyone, worldwide. That's direct experience, and 100% fact. Claim whatever motivation that you'd like, proof comes from 21 years of my direct experience with Nikisil. That said SUMEbore development has been underway and the first M9X with SUMEbore is already running. I am building the first Aircooled Nikisil SUMEbore direct test engine now. It uses the bank 1 cylinders with LN Engineering Nickies, and the bank 2 cylinders with LN Engineering SUMEbore. This is ONLY being done as a long term alternative, so when the laws get even mire strict, and the plating process is banned entirely, we already have the SUMEbore technology optimized, proven, and therefore will continue to kick everyone else's *** with both Aircooled, and water-cooled Porsche engines, and development. That's what we do.

Uh-Rah!

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How does it taste ?

I will answer since Jake is here. He is one of the few on this board knowledge enough to know what I’m talking about and keep a discussion about it. GT3/GT2 and turbo is not the same engine as in the standard 996/997. It’s like saying that the 2zr-Fe (used in Lotus) doesn’t bore score because it uses steel liners. Should we all use steel liners then? The 2zr-fe have for example offset crank to lower the cylinder wall pressure during combustion. This leads to thicker oil film -> more room for debris ->Less risk for scoring + less wear/friction. You can run that engine on 0w-20 oil if you wish and it produces almost the same nm/L as the M96. The breather system on that same engine is also void of the dyson vacuum that we call the AOS, causing less debris build up in the oil. To safeguard an engine from bore scoring, the cylinder material is one of many things that can be done. When evaluating what material to use you need to know how the engine will be run. So, for general use (as I wrote in my post nota bene) Nikasil is not the best choice. It was used in mass manufacturing, failed and abandoned. Nikasil have it’s merits so for racing, and enthusiasts that know the shortcomings of it, go ahead if you like. Lokasil/Alusil is tough stuff. If it scores in normal road use I doubt that using Nikasil would make much difference. If the debris is bigger than the clearance/oilfilm, something will give. You want to see scored Nikasil cylinders? Go search two stroke dirt bike forums. And on a side note: Unless someone worked at Porsche(or have direct information), saying that they did / do something because of cost cutting is just pure speculation.

Connerie!

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So, 4+ decades of Nikisil being used on aircooled Porsche street, and race cars is to considered a “failure” or “abandonment”? I think not. We aren’t talking BMW engines here, but I think that’s where you are basing these statements. I never said the GT/ Turbo engines were the same. I build both, have you? I challenge you to find a single Nikisil plated aircooled Porsche cylinder that is scored. You will not. The cylinders fitted to my ‘88 Carrera have 280,000 miles and that engine has never been disassembled. The cylinder bores are bright and shiny, no streaking, and no scoring on any of them. This is the constant among these engines. My statement in the earlier post should not be only considered from cost cutting, but more that the Nikiail process was a required abandonment based on the environmental regulations that increased the costs of the process to the point that no one had a choice but to abandon it in mass production. Aside from using these other engines to further substantiate the effectiveness of Nikisil, I also have 21 years of direct, first hand use of LN Engineering Nickies in my engines. These are from aircooled 4 and 6 cylinder Porsche engines, VW aircooled engines (Making 760HP at the rear wheels on alcohol, with 35+ PSI boost) as well as more than 800 M9X engines over the last 18+ years. This includes the very first set of Nickies ever made, which are still alive, and making 55HP per cylinder in my Outlaw 356, where they have been used in the same engine since 2000. These are facts. Yes, I know a little about Nikisil in dirtbike engines.. I just finished my 250R today (now a 300, and a true death machine), and now my daughter is assembling the big bore engine for her F350 Odyssey, both of which were Nikisil plated in the same baths, and vats that our Porsche blocks are plated, and honed using same procedures. The reason why dirt bike engines have cylinder issues is because of rider error most of the time. Lots of people don’t allow aircooled dirt bike engines to warm up before going wide *** open. They fire then up, and go ***** out immediately, thats the worst thing possible. Get a bike engine hot, then ride it through a river, or deep mud...Thermal shock does them in. On top of that, dirt bikes constantly fight with dirty operating conditions, and people use crappy aftermarket air filters that suck dust in. I own 15 vintage Hondas, and every time one of them breaks, it gets a nikisil cylinder treatment. We ride hard, but maintain well, use the proper mixtures, and fuels, and have zero issues. I’ve bought all my bikes, and Odysseys with broken engines, fitted them with Nickies, and haven’t ever had to go back into one later.(well except for my XR200 that snapped the crank in half)

I though the 3.8 had the thinnest cylinders and the 3.4 had the thickest as the outer part of the cylinders are all the same size more material is just bored from the inner part to increase the capacity making the cylinder walls thinner if you get what I mean !

As I wrote above, for air cooled it works great, and you have yourself experienced that. We agree on that. It's when used in water cooled the failure happens in specific usage . Lokasil/Alusil have been proven to work better for a road going car . Simple as that. I'm not saying one is better than the other in total, choose depending on the cars usage. For water cooled there have to be a good reason to use it. Nikasil is not a silver bullet to stop all cylinder failure, I see it as adapting to usage. Which is what Porsche did when they used it in the GT cars, adapted for intended use. Seeing all that you have written about temperatures, oil and filters I think we can agree that this is very important to avoid scoring(and other problems for that matter). It really is the foundation for reliability. As to your challenge. Nikasil is very hard/brittle and they seldomly score, they rather crack or flake. Which is equally bad. Here is an example: http://forums.pelicanparts.com/911-e...der-marks.html Nice trike, my neighbour used to have one of those. I understand why you call it death machine, fast cornering looked like an adventure. Have a good weekend.