[RKDinOKC]

Dude, it's not just compression ratio that determines octane requirements, also has to do with piston stroke, engine load, max cylinder pressure, cylinder temps, air fuel mixture, and timing. Any high performance engine should be using higher octane fuel to run more aggressive timing.

Carbon build up soaks up fuel and oil and becomes a heat sink on top of the piston increasing not only compression ratio ie max cylinder pressure, but also cylinder temperatures.

Pre-detonation is rarely due to just the timing being off.