Stw000

How does higher octane produce more power??? Or is this a false claim? For instance most turbo'd or N2O drivers recommend a higher octane than premium for your best numbers/performance/safety... I always thougth the level of Octane measured how clean the fuel is.

any ideas would be greatly appreciated.

Thanks

dhayner

The general facts are these:

Octane number is a measure of knock resistance.

High compression ratio leads to greater power and efficiency, but causes knock.

With high-octane gasoline, you can have high compression ratio without knock.

Turbo or superchargers increase the effective compression ratio.

Octane has nothing to do with cleanliness.

pdexta

I'm gonna give it a shot, although I'm sure someone can explain it more accurately and more comprehensible than I can.

The higher octane a gas is the less prone to combustion it is. You want the fuel to ignite as the piston reaches the top of the cylinder so the explosion pushes the piston back downward. If you run a lower octane the gas ignites earlier, as the piston is still moving upward. This forces the piston to continue moving upward against the force of the explosion before it can move back down. The motor is effectively working against itself causing you to loose valuable power.

Stw000

Ok, this stuff makes since to me. As you force air and fuel into the chamber the potential to detonate sooner increases. By adding a higher octance you help to slightly delay this detonation until the pistion has reached the correct position...

Correct or wrong?

Thanks for the info guys.

pdexta

That's the way I understand it.

slalom44

Scottrunsxc is basically correct. Higher compression engines are more prone to predetonation. Predetonation is basically dieseling, or combustion without a spark. If you use a low octane gasoline and stomp on the gas pedal, you're going to predetonate. This will be detected by your engine's knock sensor which will retard your timing (the firing of your cylinder) to prevent the predetonation - the source of knocking (which is bad for your engine in the long run).

Retarded timing robs your engine of power and fuel economy for the same reason that predetonation does.