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All very good suggestions to which I would also add that you should always get a used oil analysis for every oil change so you can identify fuel dilution quickly and take corrective action. PWTA is a new technology that uses very hard, iron-lined cylinders so abnormal bore scoring theoretically should not be a problem in the 9A2 engine. PWTA has been successfully used on the Ford Coyote racing engines as well as with Porsche Motorsport. Time will tell.
The 991.2, 992, and 718 engines (and several other from VWAG) are using Oerlikon's SUMEbore process. From what I've seen with the testing we've done in conjunction with Oerlikon, Total Seal, and Flat 6 Innovations, it's great stuff. No measurable or visible wear after some pretty tough testing we did on a 3.2 to 3.8 build we did to evaluate the process.
With relation to the current 9A2 engines (or even 9A1), does anyone know how long the 997s went before bore scoring became an issue? I don’t know if there is enough experience. With regard to tracking, does the LT2 have the same issue? In everything I’ve read and seen, there isn’t one cause. I’m not even sure how many other manufacturers have this issue. Does anyone know? What about the basic H6 design verses a V? I’m sure Porsche is well aware of all other designs and subsequent experience.
The 991.2, 992, and 718 engines (and several other from VWAG) are using Oerlikon's SUMEbore process. From what I've seen with the testing we've done in conjunction with Oerlikon, Total Seal, and Flat 6 Innovations, it's great stuff. No measurable or visible wear after some pretty tough testing we did on a 3.2 to 3.8 build we did to evaluate the process.
Charles, just read your 2019 research article “Understanding Bore Scoring”. Great work. I also now understand the difference between PWTA and SUMEBore process. Thanks.
I am always amazed at the number of people on the bleeding edge who are surprised when they bleed. The only reason Porsche would have any higher an incidence of bore scoring than any other manufacturers is the number of 911's that get tracked. The reason so many 911's get tracked is how close the car is out of the box to a race car. Race cars and streetcars have different maintenance expectations. When billy bob tuned his 991.2 to 500 hp and kept it at red line for 3 hours he is still surprised when after 2 years there is an engine issue. If you took out the porsche's that are not tracked I would imagine their rate of engine failure is well below other manufacturers. If you have 70 to 100K to spend I would not try to race porsches as that is at a different financial level, miatas may suit.
Also, you are on the bleeding edge of performance. Sure a dodge can go faster in a straight line but they have no prayer of following me on a mountain road. What goes along with that mind bending performance is wallet busting maintenance. The only exception to this may be the new lotus but even with the toyota drivetrain and tranny enough time at redline and it will see race car issues.
In short worry about problems you have, if you worry about problems you dont life will seem pretty hectic.
Here is some info that conflicts with your comments around the health of a track car vs non-track car (garage queen). Tracking your 991 is not necessarily a bad thing. Personally I change my oil ever two track weekends and have an oil analysis done. I have a neighbor that does not take his 997 out of the garage...I would never buy that car.
An oil analysis comparing the health of a "babied," short-drive daily commuter car's engine to a track car's engine most often shows that the track car is in much better shape; the short-drive daily car's engine rarely gets up to operating temperature for a long enough time, so the pistons don't become warm enough to expand and prevent blow-by of fuel, water and contaminants into the crankcase; the track car, on the other hand, spends most of its time at high revs and optimal operating temperature (assuming it's not overheating), running in the conditions its engine was designed for--moisture in the system evaporates, and engine internals operate smoothly. The guest expert summed it up nicely: "Thoroughbreds are designed to run, not walk."
Yes, bad math on my part. Regardless, the number of incidents is very few. Hard data doesn’t exist. You are aware that the 9A1 engine was used in all Carreras from 2009-16 (997.2/991.1)?
Thanks for the reply. Yeah I'm happy to hear that the consensus is that there should be some bias in the RL survey and the actual incidence of cylinder scoring, particularly in the 991, is currently, and expected to remain, much lower.
The 991.2, 992, and 718 engines (and several other from VWAG) are using Oerlikon's SUMEbore process. From what I've seen with the testing we've done in conjunction with Oerlikon, Total Seal, and Flat 6 Innovations, it's great stuff. No measurable or visible wear after some pretty tough testing we did on a 3.2 to 3.8 build we did to evaluate the process.
Really appreciate it. That has definitely been my take away and my plan now is to shoot for a 991.2 or 9A2 engine model in my budget. Thanks!
The 991.2, 992, and 718 engines (and several other from VWAG) are using Oerlikon's SUMEbore process. From what I've seen with the testing we've done in conjunction with Oerlikon, Total Seal, and Flat 6 Innovations, it's great stuff. No measurable or visible wear after some pretty tough testing we did on a 3.2 to 3.8 build we did to evaluate the process.
On your website you have been gracious in providing much information including the following: https://lnengineering.com/products/w...1.html?limit=8
"Later 991.2, 992, and 718 (4-cyl) models still utilize an aluminum engine block, but the cylinders bores are coated using a SUMEbore coating."
Since the 718 4-cyl is explicitly specified, should I read this to mean that exclusively the 4 cylinder 718s got SUMEbore -- and therefore others like the naturally aspirated 6-cylinder Cayman GT4 did not? Do you know when they switched the 6 cylinder Cayman engines to SUMEbore? Presumably they must have but I just don't understand exactly when the switch occurred since I read your verbiage to indicate the 4-cylinders got it first (I guess maybe that makes sense since those are higher pressure boosted?).
Are you aware of any instances of SUMEbore failures? I realize there may be limited information as many if not all would still be under warranty and therefore there is not much information in the aftermarket. Just curious if you have heard of anything........
I've tracked this a bit and so far I'm not aware of any community reported bore scoring cases in 991.2 engines, at least in the same fashion that the 997s or a few 991.1s had.
FWIW these were also rare in the 991.1 engines... I was one of the unlucky few this happened to. But I ended up getting a rebuild by the incredible Deman Motorsports and as part of his 4.5L package he switches to Nikasil which doesn't have this issue (the underlying cause in my case was a bad injector).
Of course, that's not to say it's not impossible. if there's something seriously wrong with the engine I'm sure you could manage it.
On your website you have been gracious in providing much information including the following: https://lnengineering.com/products/w...1.html?limit=8
"Later 991.2, 992, and 718 (4-cyl) models still utilize an aluminum engine block, but the cylinders bores are coated using a SUMEbore coating."
Since the 718 4-cyl is explicitly specified, should I read this to mean that exclusively the 4 cylinder 718s got SUMEbore -- and therefore others like the naturally aspirated 6-cylinder Cayman GT4 did not? Do you know when they switched the 6 cylinder Cayman engines to SUMEbore? Presumably they must have but I just don't understand exactly when the switch occurred since I read your verbiage to indicate the 4-cylinders got it first (I guess maybe that makes sense since those are higher pressure boosted?).
Are you aware of any instances of SUMEbore failures? I realize there may be limited information as many if not all would still be under warranty and therefore there is not much information in the aftermarket. Just curious if you have heard of anything........
I am unaware of any failures with SUMEbore. From my personal experience with SUMEbore, it is awesome. If there end up being any issues in the future, it's going to be related not to the coating on the bores but other issues like shrinkage in the bores around them main bearing saddles combined with very tight piston to cylinder clearances.
I purposefully did not include in my statement quoted above the 718 GT4 as I am not 100% sure when and if they switched to SUMEbore. I would assume models with the plastic oil pan as found on the 991.2 would also have received SUMEbore, but I don't have access to information about this and Oerlikon could not confirm this with me as they just sell the SUMEbore powders and the coating equipment. to VAG.
TYVM, Charles. I always value your opinion as you are an excellent resource of high quality reliable information.
I had sent this same question to your LN support email yesterday and they gave me the same answer -- sorry for duplicating, I have been considering purchasing a GT4 but only want a model with SUMEbore so wanted to ask you directly. I am the type of person who likes to be fully sure of what I am doing before I make a decision so this is why I have been thinking about it.
Have a great Labor Day weekend, thanks again for everything, very much apprecaited.
TYVM, Charles. I always value your opinion as you are an excellent resource of high quality reliable information.
I had sent this same question to your LN support email yesterday and they gave me the same answer -- sorry for duplicating, I have been considering purchasing a GT4 but only want a model with SUMEbore so wanted to ask you directly. I am the type of person who likes to be fully sure of what I am doing before I make a decision so this is why I have been thinking about it.
Have a great Labor Day weekend, thanks again for everything, very much apprecaited.
No problem. I discussed this with Stephen after you sent your message in :-)
Nonsence, here in the Uk loads of 991.1 3.8 9a have bore score, hartec are inundated with work from them, I have a 991.1 c4s,it has now got borescore and will need new cylinders,the car has been looked after its whole life, every Porsche will suffer from Borsesocre no matter what, this is a Porsche flaw but they dont care, they got paid the high price for the car when new and as they change hands over the years some with no warranty then its not there problem anymore,they just dont care,they Do know it will happen eventually Fact
Nonsence, here in the Uk loads of 991.1 3.8 9a have bore score, hartec are inundated with work from them, I have a 991.1 c4s,it has now got borescore and will need new cylinders,the car has been looked after its whole life, every Porsche will suffer from Borsesocre no matter what, this is a Porsche flaw but they dont care, they got paid the high price for the car when new and as they change hands over the years some with no warranty then its not there problem anymore,they just dont care,they Do know it will happen eventually Fact
Ahhhh, I think you might be confusing the 9A1 engine with Alusil cylinder liners found in the 991.1 with the 9A2 engine with SUMEbore iron cylinder liners in the 991.2 and 992 models. Apples and oranges.
