What Gas should I use?

[PKRWUD]

Originally posted by Mustang_289
Chris:

I'm curious to why you would want lower octane. I'm not challenging you here I simply don't know enough, just trying to understand more. When I watch drag races on TV I always got the impression these dudes crank the octane up in the pro-stock and higher classes.

No problem. In short, the octane rating basically tells you the burn rate of the fuel. The higher the octane, the slower the burn rate / the lower the octane, the faster the burn rate. You want the fuel to burn as fast as possible, but still be stable enough to not burn faster than you want, which would create detonation. There has been a misconception that higher octane fuel is more powerful, when in fact it is actually harder to ignite.

When you do things like advancing the ignition timing, or raising the compression, you make the air/fuel mixture less stable, which can cause detonation. In order to stablize the mixture, you add a higher octane fuel.

The ultimate octane for any combination is one that results in stability with the mods and adjustments that engine has, without making the mixture any more difficult to ignite than is necessary. In otherwords, the best octane is the lowest you can use, without resulting in detonation.

Take care,
-Chris