What cylinder heads and compression? For clarification, the lowest octane fuel that meets the octane demand of the engine at its optimal state of tune will make more power than a fuel that surpasses the engines actual octane requirement that has a slower burn rate and is harder to ignite. Anytime that an increase in fuel octane increases power it usually means that it is remedying some inaudible or intermittent detonation. Any 9:1 engine should run better on straight pump fuel than 110 octane. That is unless the fuel is heavily oxygenated and you’re able to operate at ethanol like F/A mixtures.
