nosubt2

while crewing for a SPB Sunday at the Daytona race, I noticed that some teams were using race fuel in their SPB. Is this allowed because it does not say it can be used in the rules that I can find?

Streak

Our rules don't specify what fuel you can use. Some use 98 or 100 because it runs cooler but gives no power advantage since we cannot monkey with the ECU at all.

Make sense?

After a quick scan the only class that seems to specify fuel is SP911

nosubt2

Quadcammer

no, the car will not advance timing beyond its open loop tables. It can only pull timing due to knock sensor activity. If the knock sensors are quiet on 93, going to race fuel will actually hurt power.

MJP911

Quadcammer

The long and short of it is that you want as little octane as possible to eliminate detonation.

https://www.hotrod.com/articles/0901...pump-race-gas/ does a pretty good job of explaining.

Now given that track use will cause the overall engine temps to be quite high, the race fuel offers a bit of margin for error if your car may like to detonate a bit when warm, but if not, you don't gain any power and may actually lose some.

Additionally, the stoich a/f for race fuel is different.

Gary R.

Correct, there is no "tune timing for more octane" program in the ECU.. My logic was to use it on hot days to help avoid detonation and the loss of power the ECU will cause when adusting the timing for it. On my Stock D 911, with no ECU or knock sensors, I used to to help avoid detonation, period. Usually blended the 93 with it.

tgsmith4845

Streak

If you use it it's cheating. Just you

Gary R.

I'm from CT, cheating is what we do.... or in my case, did... or will do.

Streak

We know gray. We know

Gary R.

They call me Mister Gray
..

Streak

Damned autocorrect