Quote:
Originally Posted by BrianMSmith
psychological effect. Octane is a chemical added which makes the fuel harder to burn. This prevents pre-combustion, or knock, which can help engines that are either old and have carbon build up which causes hot spots, or modified high comression engines (pressure+temperature causes ignition), or engines that run extremely hot due to very high power output. Your brand new stock engine will not knock on premium fuel, unless it's 140F outside, therefore your engine will not advance the spark, which will not reduce the power output. Fact. Ask an engine engineer. Oh yeah, I am one. That's your answer.
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No offense but you don't need extensive engine modification to run race gas on our cars. The engine is already an 11 to 1 compression ratio, and the factory ignition tune is fairly tame, most advances to the timing curve benefit greatly from having a higher grade of octane. A $500 tuner is all you need to justify race gas. when the car gets hot it may be pulling timing on the factory tune some of the track guys have noted a loss of power at temps and while it could be caused purely by the raised temps, the timing has been suspect. more data-logging needs to be done to confirm it of course but the added fix of running higher octane fuels when near limp mode temps are being reached is cheap insurance. Also you never know what race gas he was running as many now contain performance enhancing oxygenators that are pour in power. I agree race gas is not going to provide much if any gain when driving around town but don't bash it's use right off the bat. If i manage to get my hands on some propylene oxide it will be good for a solid 2% gain in power in a 5% mixture ratio.
Also Octane is not the chemical added to increase the knock resistance of the engine it is usually MMT, toluene, ethanol, MTBE