This is my version of detonation. His dont look like that You cant see clearly but the top of the piston looks like a sponge over most of the top. The others not as bad but similar. BTW the rod in this cylinder was bent as was the pin on this rod pin and the ring land was beat up. Complete with a crack in the steel crank. This piston was detonated. This was a 109 in the 740+ rwhp range run very hard using alky. And yes we were very aggressive during the learning curve.