Point is, that's pretty high compression. That suggests a relatively high CR and/or valves opening and shutting to capture a good amount of volume.
In the other thread you mentioned pinging. Not suprised.
Bingo if my CR is too high it would explain the detonation possibly but also I don't know what cam is in there. Ultimately I want to try and estimate the CR but I also don't know the swept volume etc so I don't think I can do that.
