zcct04

I'm doing a road course event next week. After having run out of gas during a lunch-break run to refuel at my last event :-( I am pleased to find that the track sells gas on site.

They have three grades of fuel - 93 unleaded (contains up to 10% ethanol), 98 unleaded (contains no ethanol) and 110 leaded. On a stock engine with just a standard EC tune, is there any advantage to running the higher octanes?

Merc63

93 would be plenty

BLKROKT

Pounding the car around a road course for hours on end at high RPM and high-load? I'd run the 98 just for peace of mind. And yes, there is a difference with just EC tune. Don't run the leaded if you have cats.

Bigtickets

Sucks they don't have the non-ethanol 93 because that would be ideal. The 98 is probably 2$ more a gallon at the track. Not worth it.

And agreed on these small fuel tanks, they suck

zcct04

Thanks - that's a critical point, and I completely overlooked it.

Merc63

Lead will also destroy your O2 sensors in about 10hrs.

Diabolis

For the track get the 98 if you can. With our 11.3:1 CR and especially if you have an aftermarket tune where you're likely running an even leaner mixture, it helps to have the extra breathing room especially when you're pushing the motor hard. You won't neceassarily get any extra power out of it (the energy density of the fuel is more or less the same), but you'll significantly reduce any chance of knocking. Of course - stay away from the leaded stuff.

BLKROKT

Thank you Diabolis. Of course it's common sense. If you're wringing your hands over $2 a gallon to keep your engine in the safe zone, then I really don't know what to tell you...