Cylinder 8 issue

[luc]

2017 GT PP with power pack 2 22.000 miles
So, I only use this car for the track and to drive there
Today at Thunderhill I felt that the car was slightly down on power
Came back to the pit and check engine light was flashing
Connected my obd2 tool and code was pO308, misfiring cylinder 8
Was able to drive the car back home, about 200 miles
Pulled the spark plug... very oily... and used way more oil than usual
And insight on how to permanently solve the issue with # 8?
Dealer is going to put a new engine Under warranty but that is not a long term solution
Btw, my friend with the exact same car is on his 3rd engine with the same issue each time. And at also around the 20k miles each time

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[thelostotter]

Just went through this at 19k miles. I'm guessing you will find the ring land cracked on the #8 piston, possibly on #6-7 as well, I did. #8 was the only one that progressed far enough to fail. I didn't have the PP2 tune on the car at the time, but I did have that tune when I started tracking the car. My car would sometimes ping with that tune, and I suspect detonation damage originated there. I've never heard the car ping since adding headers and going with an aftermarket tune.

My car never seemed to run hot on the track but below are some things I did specifically to get it to run cooler or to make it easier to monitor the heat. I can't tell you that any of it solved the problem as I only have 5 events and 4k miles on the car since the rebuild.

1) Had block align honed and torque plate honed 0.010" over and am now running 2618 Wiseco pistons (more tolerant of detonation if it happens)
2) MMR head cooling mod (debatably keeps the driver side bank cooler)
3) Separated the oil and water cooling circuits. Installed a massive Earls 50 row oil cooler and -12 AN lines (this made a huge difference, sometimes it is difficult to get oil up to temp despite the 180 degree thermostat in the sandwich plate)
4) Real oil and water temp gauges installed.
5) Mix in unleaded race fuel for track days to bring octane up to 95+

My catch cans now barely catch anything. The torque plate hone and fresh rings have nearly eliminated any blow by. Car runs great, added tons of goodies while I was in there. Hopefully I get much more than 19k miles out of this one.