Just wondering how much psi have some of you cali people ran that was still safe with little to no knock counts? cause we do have the 91 **** gas in cali.

 

Depends on the tune.

I run 23psi spike on 91 octane. 05 Evo.

 

23 psi spike. Sometimes it knocks sometimes it doesnt. The knock is not bad and it doesnt pull timing. 03 Evo.

 

My car spikes to 22 psi and holds @ 18 psi to redline when I ran 91 octane gas. My advise to anyone who has an EVO in CA is NOT to use 91 octane at all. Find a 76 station that has 100 octane and mix it with 91 to get the mandatory 93 octane. That is what I have been doing since June of this year.

I still boost to 22 psi even though I am running 93 octane gas. However, I retuned the AFR and made the timing a tad more aggressive and this improved the power band according to before and after logs on datalog lab.

 

I agree on the 100 octane, but why not run a water/alcohol injection system? I've been running a 50/50 mix of distilled water and methanol for a couple of years now on my Evo. I spike at 23-24 PSI and taper to 18 PSI on 91 octane.

 

I was thinking about this question myself.. What does it depend on?

This is theoretical.. I haven't tried this yet.

If I'm forced to run 1 degree timing advance @ peak boost, while running say 23psi.. (higher timing makes it begin to knock) does that mean I shouldn't be running 23 psi on 91 octane?

Maybe try running lower boost, more timing?

I have no 100 octane readily available at the pump.. but I want to get maximum power out of the **** 91 octane.

Now I have no awd dyno around here, and the track is just about closed for the year. Dataloglab's dyno feature seems hit or miss..

So if the IDC's aren't near 100%, theres no knock, AFR's are in check (11.0's across) Can I run as much boost as i want? (And if I'm running very low timing mid-range (1,2,3))

?

 

Actually my case may be due to phantom knock . Downpipe is rattling at IDLE... and more while cruising, i'll fix that then post some results

 

We'll, different tuners use different methods from what I hear. Some will use more boost, less timing. Some retarded timing, with lean AFR. etc, etc.

If you had two tunes, say one at 23lbs & 1-2* timing at peak torque and one with 21lbs & 5-6* timing and they both are knock free, I guess you would just have to use a dyno to see what one make more torque.

 

Water injection would be ideal and I have been thinking about getting a kit, but until then I will mix 100 with 91 octane and enjoy the additional power on my car. The two logs below show the results. Both logs were done with 93 octane gas, but one (less power) was with the custom tuned 91 octane map and the other (more power) was done with a 93 octane map that I modified. It is possible that the power difference would have been greater had the 91 map run on 91 octane gas.

 

Ive added a bottle of octane booster to a full tank of gas a few times and notice an increase in performance you could try that if you like me and cant find any 100 octane in SD.

 

ya, but octane booster dosent really raise the BET's. Those octane boosters are most likley just a gimmick and what you felt was in your head ( no offence).

 

I would have to say on a stock engine with basic P.A i would say 20.5 max on 91 oct ,and use BP(amaco) or cheveron fuels they use an oxygenated formula which is what most race fuels are composed of ,,,also you could run a 12oz mix of C12 with a full tank this made a good diff.or 3gal C12 to a half tank for race day.only do this if you have a free flow exhaust and no cat!the first mix should yeild a 94ish oct,and the second should yeild a 101oct.

 

Here in California, there is no BP/Amaco. I've heard that they are affiliated with Arco and that gas is one of the worst in 91 octane form. As for Cheveron, it's not as good as Unocal/76. Unocal seems to give the best results for us here in California overall.

 

it must be fooling my knock sensor too because my evoscan(19.5 psi) gets almost no knock ONLY when I run octane booster go figure?

 

really? hits just under 20 psi and i get no knock on 91 octane. The only time i pick up knock is when the humidity is high or its hot.

Anybody elses toughts on octane booster?