B. Elliott, i know octane is not about increasing performance, i'm saying that in my saab, because it didn't ping, it allowed me to have increased performance(knock sensor). See??? i already posted that it's not about performance, and that the higher the octane rating, the less likely the fuel mix will preignite. i realize that the higher the compression, the more likely the fuel mix will preignite. just use whatever the manufacturer says to use, of course using the correct units. technically, the higher octane fuel produces less energy, but not significantly or noticably... diesel, with an octane of what..... 20's(or 40's?? i don't remember) has more energy than gasoline but is very easy to pre-ignite, that's why diesel engines don't use spark plugs, it just ignites itself as pressurized air enters the chamber- too high an octane and the engine may not run, too low, ping - no increase of performance.
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Originally posted by Ken99287
just use 87, the high octane stuff is for cars with knock sensors and forced induction applications. example - using 87 in my saab only produced 18psi boost, but high grade produces 25(knock sensor lowers boost levels), that is because higher octane makes the fuel mix harder to preignite(ignite from being pressurized), ensuring that the mix only burns when the spark plug sparks. pre-ignition/detonation is bad because it's igniting during the compression stroke-very hard on engine parts. but regular cars only need the lowest grade needed to prevent detonation. the "Porshe" badge doesn't mean it's not still just a regular ol' combustion engine. just cuz it's a porsche don't mean high grade will do miracles. now if you had a 951...
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