Steve: Octane is an additive which SLOWS combustion. Gasoline WILL burn more quickly and even explode, with higher compression, so a higher compression engine will require MORE Octane to maintain a "smooth flow" of the flame front. "Ping" or detonation is this explosion which we want to minimize for longer engine life!! Gasoline will combust just from compression and that is what we are trying to prevent. I hope I have explained this a bit better!!
Mebedez