So I just bought gas at my local Chevron and they are using part E-10 Ethanol now. What does this mean for our rotarys? Should I avoid it ? Is it OK? Will it run richer, or leaner, or hotter?
Thanks.

 

It's fine. Most gas companies mix 0-15% Ethanol into their fuel now and it makes virtually no difference at all.

Technically, since Ethanol has less chemically stored energy per unit than gasoline you'd get a loss in power or you'd have to go slightly richer to compensate and burn a bit more fuel but at 15% it's so imperceptibly small that you won't notice at all. I say "technically" because if you start talking about E90 then you definitely have to rejet for that reason (as well as a multitude of other things because E90 is corrosive to some of the materials that some stock fuel systems are made with and requires replacement fuel pump or injectors in some cases.

Jon

 

On the bright side it also "technically" burns cooler and is less prone to detonation (knock, preignition by pressure instead of spark), so one can argue that the minute loss in power is compensated for by the cooler burn because you can richen up the mix without as much risk.

Remember, I'm no expert, I've just pieced this together from what I've read.

Jon

 

OH OK. I figured it would be fine. I am running about 10 degrees advance on my GSL-SE so the less chance of knock the better. I have not noticed a difference in the rich / lean tune, infact the last time I tuned it I was dead on where I wanted to be so I'll just leave it at that. Thanks Jon.