That little bit of currugated metal is the head gasket. It blew right at the top of cylinder #4. I was going 111mph in 3rd gear at the time at Lucas Oil Raceway in Indianapolis. It was the first time covering the quarter mile since I had converted the car to run on E85. It had never gone that fast before (previous best MPH was 104), so I neglected to shift into fourth, and the gasket failed somewhere north of 5000rpm.
Here’s another shot with the head off.
There was no other damage to the engine at all, but after measuring the cylinders, #4 was way out of spec, which prompted a rebuild.