Race fuel
 

How high of a octane to use and what is legal for stu? Also leaded or unleaded is 76 110 too high for 04 sti not mixed with pump gas?

Re: Race fuel
 

Any fuel legal for use on the street is legal in AutoX.

110 is fine for an STi, but without tuning, and at our high altitude it probably won't make a difference. In fact, I'll bet a stock STi on 91 at our altitude has already maxed out its advance multiplier and isn't near knocking.

Just make sure that 110 is unleaded, or you'll nuke your sensors and cats.

You might notice some more power with higher octane gas, but not much. However, with a good tune you'll notice faster spool, the ability to run more boost and more timing advance, and a LOT more power.

The only way higher octane fuel can make more power on a stock car, is if the car can advance the timing to take advantage of the better knock resistance of the higher octane fuel.

Because it's so hard to knock up here at altitude, I can't imagine a stock car hasn't already maxed out the advance on 91 octane. Therefore, without tuning, higher octane at this altitude won't gain you power.

Now if you're running an intake to lean out the car and get it closer to knocking, then the fule might help... but really the only way to take advantage of higher octane fuel is to get it re-tuned like Kevin said.

i would say that the only way that using higher octane will help you is if you have the ability to adjust your timing curve as well as your fuel curve. without being able to do that i dont know how much difference the $3.00 more per gallon is gonna make. yup the sti and wrx can multiply the timing, but its only to a certain degreee, and im sure there is a max amount. also leaded is VERY bad for your cats, and o2 sensors. it will clog your cats and burn up your o2 sensors(o2 sensors cost like 100-150 bucks each) if you want to run higher octane i would mix vp cool blue 100 which is unleaded and see what happens. you can get this stuff at two places near the city dump off kunzli.

ryan