Damn! Car in for #6 cyl scoring. Which way to go?
#151
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I spend about a year in my free time researching this topic in depth and put out this paper several years ago. I go over everything that we know of to this point that can contribute to the problem. If you are at all interested, it's a good, albeit, very technical read.
https://lnengineering.com/education/...s-navarro.html
In the Gen 2 cars, Porsche did make changes, but I still have seen both bore scoring and piston seizing which are two separate issues with similar end results. Baz had posted about this in the past where the bores are shrinking at the bottom near the main webs. This is caused by latent stresses in the castings and made worse by the very tight piston to cylinder clearances which we have documented at .0007" cold which is very tight for a forged piston.
https://lnengineering.com/education/...s-navarro.html
In the Gen 2 cars, Porsche did make changes, but I still have seen both bore scoring and piston seizing which are two separate issues with similar end results. Baz had posted about this in the past where the bores are shrinking at the bottom near the main webs. This is caused by latent stresses in the castings and made worse by the very tight piston to cylinder clearances which we have documented at .0007" cold which is very tight for a forged piston.
#152
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#153
Three Wheelin'
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Edit: Went back and looked and I stated in my first comment but just sort of alluded to it in the second comment. Have to give you a pass on that one!
Last edited by PV997; 01-29-2022 at 10:49 PM.
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groovzilla (01-30-2022)
#154
Three Wheelin'
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I spend about a year in my free time researching this topic in depth and put out this paper several years ago. I go over everything that we know of to this point that can contribute to the problem. If you are at all interested, it's a good, albeit, very technical read.
https://lnengineering.com/education/...s-navarro.html
In the Gen 2 cars, Porsche did make changes, but I still have seen both bore scoring and piston seizing which are two separate issues with similar end results. Baz had posted about this in the past where the bores are shrinking at the bottom near the main webs. This is caused by latent stresses in the castings and made worse by the very tight piston to cylinder clearances which we have documented at .0007" cold which is very tight for a forged piston.
https://lnengineering.com/education/...s-navarro.html
In the Gen 2 cars, Porsche did make changes, but I still have seen both bore scoring and piston seizing which are two separate issues with similar end results. Baz had posted about this in the past where the bores are shrinking at the bottom near the main webs. This is caused by latent stresses in the castings and made worse by the very tight piston to cylinder clearances which we have documented at .0007" cold which is very tight for a forged piston.
I've read your white paper previously and don't remember you implicating the piston coating. Curious if you agree with Baz's thoughts regarding Ferroprint (soft sprayed coating on 2001+ M97/98) vs. the harder plated coatings (Ferrostan and Ferrotech (9A1)). Baz seemed to think it was a key contributor in the 996 and 997.1 scoring. I'll borrow one of his photos of some serious Ferroprint pealing since Rennlist won't let him post.
Always ready to learn from your comments. BTW, how do you handle 9A1 scoring since it has a closed deck? Is it a hone and resleeve or something different?
![](https://cimg6.ibsrv.net/gimg/rennlist.com-vbulletin/1024x683/peeled_feroprint_e61d3f66966ef9a294fa3e0fd31b91caf3d163fc.jpg)
#155
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I haven't seen any mention of this. Do you have any links to educate me? I have heard that cold seizure is the primary potential failure and this goes back to a few blocks with problems during casting that eventually warp to oval near the base of the closed deck. But flaking is new to me. Thanks in advance for any information you can offer.
#156
Three Wheelin'
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Woah, take a deep breath and step back from the edge. The scoring is not a time bomb, it just eventually fails and when it does you fix it. At least it doesn't do collateral damage like some other potential high performance engine failures. It does suck when it happens to you, but fortunately we got guys like Charles who can fix you right up.
The 9A1 in the 997.2 and 991.1 can also score. But by virtually every account it's at a much lower rate than the 997.1 so we got that going for us, which is nice. I sold my 997.1 with 90k miles and never had a problem. Now I've got a 997.2 Turbo with 50k miles and no problems there either. Both are California cars though, and extreme cold weather does seem to be a factor in the failures.
The 9A1 in the 997.2 and 991.1 can also score. But by virtually every account it's at a much lower rate than the 997.1 so we got that going for us, which is nice. I sold my 997.1 with 90k miles and never had a problem. Now I've got a 997.2 Turbo with 50k miles and no problems there either. Both are California cars though, and extreme cold weather does seem to be a factor in the failures.
#157
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I haven't seen any mention of this. Do you have any links to educate me? I have heard that cold seizure is the primary potential failure and this goes back to a few blocks with problems during casting that eventually warp to oval near the base of the closed deck. But flaking is new to me. Thanks in advance for any information you can offer.
. Several 997.2 cylinder wall flaking posts on various Forums as well as some on UK forums that I have read over past year.
#158
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Woah, take a deep breath and step back from the edge. The scoring is not a time bomb, it just eventually fails and when it does you fix it. At least it doesn't do collateral damage like some other potential high performance engine failures. It does suck when it happens to you, but fortunately we got guys like Charles who can fix you right up.
The 9A1 in the 997.2 and 991.1 can also score. But by virtually every account it's at a much lower rate than the 997.1 so we got that going for us, which is nice. I sold my 997.1 with 90k miles and never had a problem. Now I've got a 997.2 Turbo with 50k miles and no problems there either. Both are California cars though, and extreme cold weather does seem to be a factor in the failures.
The 9A1 in the 997.2 and 991.1 can also score. But by virtually every account it's at a much lower rate than the 997.1 so we got that going for us, which is nice. I sold my 997.1 with 90k miles and never had a problem. Now I've got a 997.2 Turbo with 50k miles and no problems there either. Both are California cars though, and extreme cold weather does seem to be a factor in the failures.
Don’t the Turbo cars have different cylinders and cases?
#159
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We might have different definitions of timebomb, but when I am looking at catastrophic engine failure, yeah, I think timebomb is accurate. A 15-25k repair because of a single scores cylinder? And this coating is wearing out on all of these engines…..
Don’t the Turbo cars have different cylinders and cases?
Don’t the Turbo cars have different cylinders and cases?
What options have you looked at for a replacement Engine LN, Flat 6, local builder?
#160
#161
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From what I have found it looks like LN has very solid kinda "Bone stock type motors build with all the upgrades" For a very solid every day driver car, for low 20's. and they or the shop next to then will do install. (to stock but a very high quality reliable solid build)
Or Flat Six Motorsport's in GA., has several options that go above and beyond the LN option. But I can only mange the cost increase.
what do you have 997.1 or 997.2
Last edited by BNB911; 01-30-2022 at 02:55 AM.
#162
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Wayne I addressed this question another thread and copied/pasted the Posts from various forums regarding the flaking/scratching of cylinder wall coating on the 997.2 engines
. Several 997.2 cylinder wall flaking posts on various Forums as well as some on UK forums that I have read over past year.
. Several 997.2 cylinder wall flaking posts on various Forums as well as some on UK forums that I have read over past year.
I have Baz's technical report with pictures and details. This was distributed per a signed NDA agreement and covered the 997.1 primarily with a short section at the end discussing the 9A1. This report implies for the 9A1 the failure mode is cold seizure and only on a few blocks that he feels were destined to failure from the time they were cast. In other places he has stated he was sharing his details with Jake and Charles but I have not been able to find anything beyond that point.
Sorry about drawing this out. I believe it is too easy for all of us to get confused regarding these motors and their failure points. I also feel it's important we try to make sure we're all going down valid paths. I'm still trying to figure out what path that might be for the 997.2 owners. This isn't a battle about who is right and not. Just an attempt to make sure we're not confusing ourselves, me included.
Last edited by Wayne Smith; 01-30-2022 at 01:33 PM.
#163
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linder---> Spend the $350 - $375 and go to your Indy and get Bore Scope Inspection through spark plug holes w/3 photos of each cylinder. See where health of engine is at.
Do you have high oil consumption?
Either way get the inspection. Will be great for peace of mind and also important resale whenever the day comes. I can't tell you how comforting it is to know my engines cylinder walls are in excellent condition at 106K miles.
Important stuff.
![thumbup](https://rennlist.com/forums/graemlins/thumbup.gif)
Do you have high oil consumption?
Either way get the inspection. Will be great for peace of mind and also important resale whenever the day comes. I can't tell you how comforting it is to know my engines cylinder walls are in excellent condition at 106K miles.
Important stuff.
![thumbup](https://rennlist.com/forums/graemlins/thumbup.gif)
#164
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As of now, I bought the car with just a tic under 60K on it 4 years ago, and it now has 97K. I drive it as it was intended to be driven, but I take exceptional care of it too. It simply does not use any oil. I rarely have to add any, maybe after a track weekend I'll be down a 1/2 quart, but that's it. I get a Blackstone report at each oil change, and it reads near perfect - within each spec. No lights, no power loss. So right now, I'd say no scoring. Now's the time to sell it I think. These threads are starting to freak me out!
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BNB911 (01-30-2022)
#165
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We might have different definitions of timebomb, but when I am looking at catastrophic engine failure, yeah, I think timebomb is accurate. A 15-25k repair because of a single scores cylinder? And this coating is wearing out on all of these engines…..
Don’t the Turbo cars have different cylinders and cases?
Don’t the Turbo cars have different cylinders and cases?
Both the NA and Turbo 997.2 (and 991.1) use Alusil for a monolithic case/cylinder construction (the 9A1 engine). The Turbo case undergoes additional post-casting heat treatment to stabilize and strengthen it, but it's fundamentally a reinforced version of the same block. It seems to have worked as 997.2 Turbo scoring looks to be pretty rare (anecdotally) though it's not unheard of. Porsche went to the 9A1 engine for the GT cars a few years later with the 991 model.