How much boost are you trying to run. I dont think you are really going to see a difference between 91/93 octane.

If you are that worried, just have your tuner take a bit of timing out of it.

 

I run about 14.7 lbs of boost when stable, spikes go as high as 16, 17.. so i do notice a difference... Don't know about others on here.. Will definitely feel a difference when I get chipped to 19lbs!

 

Try adding Toluene, it's 114 octane. It is actually a component of gasoline not an additive. You can get at the paint store for about 7 bucks a gallon. It's really 'hot' paint thinner. I read a thread on Rennlist about a guy in Cali using it in his Cayenne with success. U can get it in 5 gal. cans.

 

Thanks,

I know it’s a good proportion of pump gas. I’ve read 2 or 3 articles about it. Written by knowledgeable people and quite convincing, but opposite in there conclusions.

The negative one essentially implied it wasn’t difficult to reach a saturation point where it caused the mix to burned to fast or to slow or something and actually going over the law of diminishing returns. But they didn’t exactly say if there is a ultimate mix.

I would be surprised if I can even find here in So. Cal.(emissions). But if I do find it I’ll sure give it a try. In the mean time I’m setting up for h20/meth. Injection which should make the issue moot and allow for some significant extra boost

Regards, PK

 

Hi PK2, What type of car and what is your boost level. I can run 18 psi with gt 30s and not have a problem on 93. I can turn it up some more but for sort burst. I also have a few 996 turbos out there running 24/25 psi with gt 28s still on 93 all have big intercoolers. watch the meth/water injection unless you can tune for it it may do more bad then good. Can you hear detonation ? Is the anti knock stepping back your timing?
Tim

 

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Hello,


You make me drool. I've got a little Boxster with a 2.5L . Around here we only have 91 octane at the pump. But, about 2 gallons of 100 race fuel per tank makes 93. Haven't had any detonation as I know it, The current crappy little AIC doesn't retard the timing at all, it just richen's the thing up. (not for long)


The very limited space leaves me stuck with pretty small super, only so much hp net gain you can get. I,ve chosen WI (H2O/meth) because without getting pretty drastic, theres just no convenient place for an efficient intercooler in that car ( I like my trunk).


So I'm upping the boost with a smaller pulley to about 7psi. Transplanting a much better AIC in. It has an extra fully mappable channel I'm using to control a PWM solenoid valve for precise, fully atomized WI delivery. For minding it's going on's, I've plumbed in 2 EGT(exhaust gas temp.) sensors & gage and, a w/b O2 sensor & gauge.


So, as to WI, I'd be interested in your concerns. I'm not sure how I could improve on what I'm putting together. As to tunning the WI, I guess the only tools I have are timing retard the WI map. The EGT readings,how to interpret the them is a little fuzzy (I've only heard 700c is good, 780 & your burning up). But those numbers have to be relative, so,,,


So anyway, let me know what you think. I love to hear about any and all WI pratfalls.


Regards, PK