I don't generally consider fuel to be an engine mod, so I'm asking this here. I have a local gas station that now has 99 octane fuel at a ridiculous price. does anyone run this or is it even safe or benificial for my car. it's a "11 Wrx.
I use 104 octane in my '68 AMX, but that is used to help it run better (used to run on leaded fuel). As my for STi I've only run 94 in it. Dont wanna pay for anything higher. I'm actually curious to see what people say about it too. I've thought about putting higher octane in my STi too.
Higher octane will allow you to run a leaner tune, more advanced timing, etc..(more power). because of it's ignition characteristics, but I don't know that higher octane in itself will yield any benefits
Find out if the 99oct stuff is leaded or unleaded.
If you have catalytic converters on your car do not run leaded gas. Lead kills cats.
You should only run ridiculously expensive fuel at the track. If you're not running the engine at full tilt (at the track), then the extra price you're paying is a waste.
Also, to take full advantage of the extra octane the ECU needs to be programmed for it (custom map).
Your car shipped with a conservative, "one size fits all" tune that will deal with variation in octane levels/fuel quality in North America. If you went to a tuner, and had him optimize your maps for the 99Oct. (Is the Canadian octane rating the same as in the U.S.?), then he could probably pull out a little more power...but you wouldn't want to then run that map with normal gas.
It's not worth it unless tuned for it and you're at a track. At the track day I took my STI to last month, I wouldn't/couldn't run the 100 octane they had because I have a stage 1 91 octane tune and the car probably would have barfed if I'd put the 100 octane in. I was curious what it would've done, but at almost $8 a gallon I didn't feel like it. I spent $120 in fuel on 91 octane that day anyway!