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Could you give us a bit more info for your engine & tune?

Standard BOE T4e tune?
Do you have any AFR logs?
What fuel were you running (pump gas, E85, etc)?

I'm not an engine failure expert by any stretch, so take this with a grain of salt... but what I see is more wear on the exhaust side of the piston. That makes me think it's heat related. The wear looks uniform cylinder to cylinder, so it doesn't look like a fuel inconsistency problem.

Do you have internal bore gauges? Would be interesting to try to get a good measurement on the bore diameter & piston diameter.
 

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Discussion Starter #23 (Edited)
Excelent points!
Yes the exhaust side is more worn down.
My very initial tune had some knock around 5500rpm. Not sure if it was standard BOE tune. Pump gas 92 octane. I drove the engine probably around 50 miles (trying to set the piston rings) but not going wot. Then I had the engine on the dyno and had the tune reflashed (as I recall they had a car with the same set up as mine that they worked on at the time) All of the Afr logs looked good and as preventative measure I used boostane or torco octane booster to stay safe when autocrossing. I have air/fuel gauge and I would see 14.6 AFR at 50% throttle sometimes but 10 or 11 at wot and 13 -14 part throttle.
So it’s possible that my very initial knock started some damage and maybe my oil pump was not generating enough oil pressure??? - wiped cam makes me think that oiling was also a factor.
I have a bore gauge so I might do some measurements to see if they were not honed perfectly...
 

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Discussion Starter #24
So I finally measured my bores and pistons and the piston ring gap:
1265880

And It’s waaay out of specs!!!
It should be around 0.018” or 0.020” but it’s bigger than my biggest feeler gauge 0.030”
Looks like it’s double the size...
 

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Are those marks on the cylinder bores deep? Can you feel them with a fingernail? All of these bores will have marks, whether they are gouges is a diffferent question.... Based on your pistons I would think so, but worth checking.
 

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Discussion Starter #27
So I talked to my local engine builder and the damage looks to him like the engine ingested some crap. Problem is that during the assembly everything was squeaky clean, I never run the engine without a filter or had vacuum leak. I didn’t replace the oil coolers last time when my engine had some scoring so that might be the culprit...
The rings had a very sharp edges so that’s why possibly the gap is so out of specs.
 
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