Octane rating has no direct impact on the deflagration (burn) of the air/fuel mixture in the combustion chamber. Other properties of gasoline and engine design account for the manner at which deflagration takes place. In other words, the flame speed of a normally ignited mixture is not directly connected to octane rating. Deflagration is the type of combustion that constitutes the normal burn. Detonation is a different type of combustion and this is to be avoided in spark ignited gasoline engines. Octane rating is a measure of detonation resistance, not deflagration characteristics.

It might seem odd that fuels with higher octane ratings explode less easily and are therefore more powerful. One simple explanation for the effect is that various fuels can provide different heat (therefore energy) at different compression levels. As the compression level increases on many fuels so does the heat (energy) per unit of measure of fuel.