I'm sure this has been asked before, but i couldn't find it in search. Just curious how much daily boost are you guys running with our crappy 91 octane gas?

id like to know the same cause weve only got 91 in vegas. but at some pumps its 100 but thats like over 5$ a gallon

19-22psi was the highest ive went, no detonation but I was running a decent water/alcohol injection. pulls hard.

edit: but eats gas like you would not believe

also depends on your turbo, i have a 16g

Highest I have gone on pump is 20, but I am a 4g63. I daily 15 right now, pulls like a champ.

18psi on S16G with stock ignition. 19-21psi with MSD. Brand of gas matters, Mobil being better, 76's ethanol being worst.

thedawg, that's with 91?

Do you think that with 93 octane, you could have run 19+ psi on the stock ignition?

Thanks,
Brian

higher octane = harder to ignite.

Yeah, I get the whole "octane" thing.

That's why I asked if it was possible.



Brian

Originally posted by ForceFed420a
thedawg, that's with 91? Do you think that with 93 octane, you could have run 19+ psi on the stock ignition? Thanks, Brian

Yes, thats with CA 91 octane. I don't THINK anything. Put the fuel in your car, and tune for your engine. What works for one person won't work for everyone.

Fair enough. Didn't know if you tried it before. I do understand what works for your car may or may not work for mine, but I figured I'd ask anyway.

Thanks,
Brian

FWIW, I've tried running Toluene to raise the octane to 98-100ish and ran into timing problems. I think fuel isn't as much a factor as ignition is at 18+. Jamesman's car runs 19-21psi on 91 octane with MSD DIS2 and Greddy Emanage. My goal is 25psi but I'll need MS&S to get there.

Originally posted by thedawg
FWIW, I've tried running Toluene to raise the octane to 98-100ish and ran into timing problems. I think fuel isn't as much a factor as ignition is at 18+. Jamesman's car runs 19-21psi on 91 octane with MSD DIS2 and Greddy Emanage. My goal is 25psi but I'll need MS&S to get there.

hey dan,

gas has pre-ignition qualities, higher octane has less than lower octane...meaning its less prone to explode by itself under heat and pressure. a good example of a gas with pre-ignition qualities is diesel. diesels cetane # is like gas' octane number. drastic example is heptane which has a octane rating of 0. higher octane = less tendency to knock, pre-ignite, detonate...what have you, under heat and pressure....which is what more timing advance and boost bring.

anyway, in a perfect world...gas couldnt explode by itself, letting us run enough ignition timing for max power, push as much boost as we wanted...and not sling it apart all over the road. ignition timing has to do more with how high the cylinder pressures will peak.

i ran 22psi on a 16g with stock ignition and 19* timing advance if i remember right. the lower comp 8.6:1 CR wiseco pistons im sure helped. 91 octane....a sidemount and water/alcohol injection. i think the problem is the octane, not the timing. pull timing...pull power. also advancing it to much you can lose power as well. pressure peaks between like 15-20* IIRC. either way detonation is the killer, and higher octane is more beneficial than pulling timing, at least in my opinion.

edit: your problem may have been with a lean misfire or something, not enough fuel...something along the lines of fuel tuning. who knows... but i dont think ignition was the problem in your case.