That's a given. More violent a combustion without knock will of course net more go power. Correct me if I'm wrong, but the actual enthalpy (internal energy produced plus actual pressure x volume) of 87, 89, and 93 are pretty much the same, meaning the energy created by each of them doesn't vary much from one to the next. But the amount composition of the hydrocarbons used in gas, like Frank said, varies which changes the smoothness of the burn. Heptane has an octane rating of 0 and is real explosive burning, where as isooctane has an octane rating of 100 and is smooth burning, I guess all because of the molecule constuction/layout. That's what gas octane stems from, so 100+ octane gas is actualy off the charts.

It's funny...I've gone back and read all the previous posts in this thread and it went from laymans terms for joe blow, to me screwing it all to hell. Sorry.

And oh yeah, carbs suck balls.