Nasty head. This poor head was destroyed when a turbo seal let go and added quite a bit of oil to the intake. The oil effectively dropped the octane rating of the fuel and the engine spent most of a weekend at the track running hard on detonation. The marks in the head were caused by chunks of the pistons that broke off above the top ring. Cylinders 1 and 4 looked like this and 2 and 3 looked like they had lost a lot of aluminum by erosion. Amazing amount of destruction. The engine kept running though the whole adventure.
In the end the customer needed a new set of pistons but the MID sleeve walls were close to new - just a hone ‘touch up’ and they were back in service. The Darton sleeves are some pretty tough items!