ignite in a Diesel cylinder (wheres Mike Smith?
>> it 🙂 ). Oh, yes. Joe pointed out that diesel’s vapor point is about twice that of gasoline. Remember, now, that liquid fuel will NOT burn in a combustion chamber environment (maybe even at all). It must be forced into a phase change into a vapor, which will readily burn. Now, in a gasoline engine, pressures and temperatures are such that the remaining liquid fuel is vaporized well and “predictably” during the compression stroke, thus being rendered “burnable” at the correct moment during the cycle: having maximum BMEP at approximately 76 degrees ATDC. Putting your timing signal too early (pre-ignition) moves this pressure point up, so that you’re pushing down on what amounts to a column instead of a crank arm. Detonation results (usually) from having combustion chamber deposits that serve as secondary ignition sources. Multiple flame kernels result, and the pressure waves generated during combustion interfere with each other, thus producing the “knocking” sound, and raising the BME
