My VR6 track car had a new head gasket as it mixed oil and water on number1 cylinder. The head was skimmed checked an fitted with new gasket.
We then done brands hatch track day and I noticed a pinking that was quite loud and only at full throttle. Bring off 1/4 throttle and it was quiet.
At the end of the day I was black flagged for blue smoke.
Came in and noticed a missfire.

Compression test showed 150-160 through all cylinders apart from number 1 which was 50
Took the head off and found this???




You can see the mark on number 1