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I had wondered also, this is what AI says, so nothing newer than 2022 to report.
Sumebore is doing well, demonstrating promising results in Porsche 996/Boxster engine development through a dedicated project, though the technology is still in its developmental stages and not yet widely available for consumer application. Initial tests, including a 3-year, 15,000-mile field test, show the technology's potential with impressive Abbott Firestone curve results and a clean bill of health from the test engine, indicating that Sumebore could offer a robust solution for combating the known issue of bore scoring in these engines, according to a recent YouTube update from early 2022.
Sumebore's Progress:
Positive Performance Data:
Tests on the Sumebore cylinders show exceptional Abbott Firestone curves, which indicate improved surface finishes and functionality compared to other methods, according to this YouTube update from March 2022.
Anyone know what's going on with SUMEbore coating? That was supposed to be the next thing after Nickies. Before JR left the forum, he was researching it and said he initially had good results if I'm remembering correctly. That was a few years ago.
Since Oerlikon closed the SUMEbore line in the US, blocks have to go to Switzerland to be coated. It adds cubic dollars and time. Currently it's a process only available on R-Series engines from Jake.
I sold my Boxster that had one of the SUMEbore test engines to Lake Speed Jr. He's still happily driving that car all over the place.
Follow up after 500 mile of Techron to clean up the carbon. It did a decent job of cleaning the carbon but that is the only good news.
Cleaner cylinder walls in #6 now reveals scoring more so than the dark possibly carbon lines before. The scoring is on the top of the engine. 180 degrees above the oil that is pooling in the bottom of the cylinder. NOT IMPRESSED!!
I guess I don't need to pull the motor to do the cam shaft guides as that is a fart in a hurricane at this point. A few pics for reference below....this is a 99 3.4L C4 Cab
Now to figure out what to do. WIll reach out to LandN, Hartech and a local shop. I don't see this being resolved for under $22-25k which is what I paid for the damn thing but she's a keeper so I'll have to make a choice. I think I'll drive and monitor for the winter. I need to keep an eye on cam deviations though...not sure how long I can really let that go. No CEL but bank 1 is at 7.8. Again....2 thumbs down not impressed.
Cylinder and piston is cleaner after 2 tanks of techron and an italian tune up I'm guessing the oil is getting in now that the bore is scored and there's a gap?? 2 thumbs down
I had a car scoped today that I'm considering purchasing that has a 3.6x51 engine with ~35k miles. There is some light scoring on 1,2,3, and 5 from what I can see. The worst looks like cylinder 2. With cylinders 3 and 4, I'm not sure if that's light scoring or normal wear and streaks.
The filter and sump looked alright, nothing too large in there. The oil was too fresh for an analysis so I held off on that.
What are your thoughts on how these look?
I haven't scoped my own car yet which is a 2002 c2 with 68k miles. Oil analysis so far is good, but I'm looking to scope it soon.
Got my 2004 cabriolet in November 2024 and PPI showed mild bore scoring on cylinder 6at 77k miles. Generally no smoke on start-up, and no oil burning between oil changes (2500 miles). I tracked the car right after I bought it, and it performed admirably. Since then no track days, I'm assuming that if i drive responsibly (DI40 or DI50 oil, frequent changes, no high revving until oil gets warm, etc.) I can drive until it starts to burn oil. I just added Tribotex at last oil change ( 82000 miles) and hoping that gives me a few more smoke free miles before rebuilding rears its ugly head.
I'd like to know if anyone has developed a spreadsheet of the cost associated with the various rebuild options. Everything sounds expensive, but it would be nice to have rough (perhaps very rough) ideas of what the options are. I had a C5 Corvette prior to my 996, and the dearth of threads on the Corvette forums relevant to SEDS (Sudden Engine Destruction Syndrome) makes me long for the sound of an LS engine behind the seats. (couldn't find the apostasy emoji)
Last edited by Modern356; Nov 5, 2025 at 12:30 PM.
spark plug holes; which i realize is less "100% conclusive". I was getting a little bit of misfiring due to the plugs and ignition coils aging out which is why they were in there. Even so I was happy that it was "good news".
spark plug holes; which i realize is less "100% conclusive". I was getting a little bit of misfiring due to the plugs and ignition coils aging out which is why they were in there. Even so I was happy that it was "good news".
Actually, spark plug hole bore scoping is 100% accurate contrary to some opinions. Hartech/Slacker, probably the biggest m96 builder conglomerate on the planet, agree and recommend spark plug hole scoping.
For those that disagree please show pics of m96 cylinders that only have bore score below BDC. Asked for these pics before and no one seems to have any.... Thats got to tell you something. Pics have been posted on this forum showing how spark plug hole scoping shows up all bore score engines.
But by all means don't believe and get under your sump, get oil dripped in your eyes and camera while trying to thread a scope thru convoluted wrist pin holes while turning the crank to get the perfect piston height to allow the scope to thread thu.... good luck with that.... many a scope has been pinched/crushed doing this unneeded procedure....
If no bore score seen from spark plug holes, you have none, you're good to go for sure...
We just had someone who is looking at buying a used 2002 Porsche 996 just emailed us with this. The seller had these photos from a PPI done by a "specialty Porsche shop". The PPI stated “small stuff, nothing too scary” - but that's not true. I will say good on them that they scoped it through the sump, but this is very early bore scoring and something that you won't see from the spark plug side. At this point, it's going to fail from bore scoring - it's not a matter of if, but when.
The whole point of scoping through the sump is make sure that it hasn't started at all yet. Through the spark plug won't tell you that.
Don't know why Hartech thinks all borescoring can be seen from the sparkplug holes, when it starts at the bottom of the cylinder walls. Doesn't matter, I'll stick with recommendations from Charles.
When it comes down to it, it's your car/potential car, and your money. Do what you're comfortable with. I'm on the search from my next 996 and when I find a car I like I'll pay to have the sump dropped and the cylinder bores scoped from the bottom. up so I have peace of mind.
As for no one sending Allcool pics of borescoring below BDC, Charles just did. The vast majority of 996 owners are not on this site, and those that are may not be paying attention to his post so no reply's doesn't mean it never happens.
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