jderou_GXP

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Fooling DoD

indynotch50

There it is! I knew there was something out there but I couldn't find it! Thanks.

06 SS

you're killin' me here Lew...Octane only influences the flash point of the mixture. Once it ignites, the flame will propagate at the same speed under the same conditions. Pulling a number out of the air, let's say that it takes another 70F to ignite 91 Octane vs 87 (and just a made up number). Once it fires, the mixture burns much hotter than it takes to ignite. All higher Octane does is keep the reaction from starting until a higher temp is reached. Once the reaction starts, you have enough heat from the gasoline molecule chain breaking down that they both burn at the same speed. Like if you had a piece of paper and hit it with 900F, it burns immediately. If you hit it will 970F, it burns immediately. The heat will travel in the combustion chamber at the same rate under the same conditions.

06MonteSS

hahahaah...

well, may I stand corrected then...

I've always known it to be that higher octane fuel burns slower than lower octane fuel...

"The higher the octane rating, the slower the fuel burns. Therefore, the lower the octane rating, the faster the fuel burns. Now at first this may sound like a bad thing, and many ask "Shouldn't a higher octane burn faster and be better for my car?"

The answer is no. If you've ever heard a "ping" in your engine and someone has told you to get a higher octane fuel, that is because the ping is acutally from the explosion of gasoline in the engine. Gasoline should not explode, but rather it should burn as quickly as possible. A lower octane rating will burn faster, and under the right conditions actually explode, causing that undesireable ping. Upgrading to a higher will allow the fuel to burn slower, therefore not exploding. "

"High octane fuel has more detonation resistance compared to lower octane fuel.
High Compression Ratio + Lower octane = Faster Combustion = Preignition/knock

higher octane = slower combustion"