Ugh. Conceptual help time

[FJman]

I'm talking to someone on another board, who's spraying an R6.  Rather, he's planning on doing so.


He states that he can run a 20 shot of spray without extra fuel, becuase he's running 110octane.  I get this, it's a tiny shot and shouldn't be too terrible.

However, then he says that you can run a motor on the dyno on pump gas and then run it on race gas and watch the a/f mixture change, becuase more octane = richer a/f mixture.

Someone hook me up with ammo to explain it a bit clearer to him?  Or put me straight if he's right, but last I checked fuel was fuel, as far as a/f ratios (with some minor fluctiation with oxygenation/specific gravity).

[dakinebusa]

Octane is resistance to detonation as measured in a Waukesha test engine.
A/F ratio has all to do with the amount of carbon, hydrogen and oxygen in the fuel and the amount of air that is used for combustion.
C, H, O fractions in the fuel cannot be correlated with octane.
That takes chemical structure information.

[badassblackbusa]

well to be make this easier more octane prevents detenation from too much heat so it will do what he is trying to accomplish but not by changing a/f ratio. unless its an oxynegnated fuel then it will make it leaner .

[BrutalBusa]

A higher octane fuel is harder to ignite and keep burning, it takes more compression to make it burn properly. It could effect your A/F because the fuel isn't being completely consumed during combustion. It would affect your A/F ratio, not becuase you have more fuel in the mix. It would affect it because less of it being burned.