Daygoslow wrote: David Redszus wrote:
Maybe it slows down the burn, I don't know. But it does something.
A slow burn would produce an increase in detonation.
forgive me if i am wrong but i thought higher octane fuels burned slower which is why they can handle the higher heat associated with higher compression without igniting? if it slowed down the burn wouldnt it help prevent detonation?
If one were to dyno an engine using a low octane race fuel, and after noting torque and lambda values, were to add TEL to raise the octane, what would be the result? There would be absolutely no difference unless the engine was alread running in detonation.
Octane has NO affect on flame speed whatsoever. What octane actually does is lengthen the time during which the unburned end gas can resist autoignition. It buys some time to allow the flame front to burn the end gas before it can autoignite.
Flame speed is the combined result of laminar flame speed and chamber turbulence (usually squish velocity) which add together to determine how rapidly the flame will propagate across the chamber.
If two fuels had the same octane but were otherwise different in composition and properties, they would not burn the same.
If two fuels had the same composition and properties but were different in octane, they would burn the same as long as the limits of detonation are avoided.