[Fenring]

I'm not versed in engine mechanics, so I'm a bit confused about the fact that higher octane fuel burns more slowly. I thought that the whole point of using higher octane is to facilitate higher compression ratio. Higher CR in turn should cause the mixture to burn more quickly. In terms of physics this would mean that, although the net energy produced by explosion is the same as in lower CR engine, it happened in less time, so the power of explosion is greater. This would than increase the efficiency at which the expansion of hot gasses is transferred as force to the piston, generating greater torque at the crank and further down the line.

In extreme example I could equate this to the fact that although my arm can throw a basketball (for instance) with far greater kinetic energy than the bullet fired from a gun has, I could never through a bullet so strong that it would kill someone. The power with which I throw a bullet is much lesser than the power of the explosive in the cartridge, because it takes my arm, I'm guessing, a good quarter of a second to swing while the explosion lasts mere milliseconds.

When thinking how could lower octane fuel beget better performance, I'm leaning more toward the explanation that it might have something to do with energy density of fuel which can vary with additives. Although I find it hard to believe such differences would be noticeable.