Race gas compression limit?

[Silverhatch]

To the best of my knowledge, its a general rule that regular pump gas has a compression limit of around 11-1 before one starts "pushing" it. Then one switches to race gas. Well where does race gas top out at a safe standpoint compression-wise? I assume that when this point is reached, one switches to alcohol? Still thinking about throwing a blower on my 10.7-1 414w, something around 12-14 pounds. I know I will need race gas, I won't be anywhere close to needing something crazier fuel-wise, just curious what compression would be on the above combo and the max compression point of race gas.

[Rodeheaver's]

vp sells fuel that will make 18:1 work correctly..

[CobraII]

The link has some info on their different fuels.
http://vpracingfuels.com/fuels_leaded.asp

I'm not smart enough to talk about the ins and out of the O2 sensors, stuff like that... but keep that in mind if you boost it enough to need a leaded race fuel. The highest octane unleaded I've seen is 100, available at Campbell's Sunoco on Route 30 in Irwin/N Huntingdon. I think PRP sells VP's 100 unleaded.

[phillysrt4]

D'Inuzio (i think thats the spelling... its been 2 years) Sunoco on rt 30 in Irwin also sells 104 unleaded. You can get VP Motorsport 109 from their distributors which IMO is the best unleaded race fuel you can get. I had great results with it and fully endorse it.

As for what's safe to run with boost, there are so many factors you need to consider (such as effective compression, total timing, and air-fuel ratio) that there is no one solution to your problem.

However, discussing this in terms of effective compression, here's a point of reference: my car was 8.8:1 running 24 lbs boost for an effective compression of 23.2:1. I could run 104 (or 100 if I ran it down to the point of being virtually empty) and not get kicked out of my 100 octane tune. If you are at 10.7:1 and want to run 12 psi you have an effective compression of 19.4:1.

Key words: my 100 octane tune.

As you can see its not as cut and dry as "if I have X compression with Y boost and my fuel is Z octane I will be fine".

Personally, I wouldn't mess around when it comes to fuel. When in doubt get the highest motor octane fuel you can find. If you're not running through cats then it opens up the option of leaded fuel. It would be a shame to put together a fine car just to pop the engine because you tried to "make do" with your fuel. If you can get some dyno time, put in the best fuel you can and start with some rather conservative tuning parameters, then step it up until you get knock. This will give you a point of reference in the event an even higher octane fuel comes your way, or if you want to dial it back for street duty.

Hope this helps.

[AdamantiumSilvr]

Yeah, I'd like to know more about fuel types and combinations for usin them. What if I'd throw a splash of Turbo Blue in my ride? Would it hurt it? They sell it out my way at the gas station near Lernerville Speedway.

[Martin0660]

What if I'd throw a splash of Turbo Blue in my ride? Would it hurt it?

First, more octane than you need will HURT performance. Octane is effectively a measurement of the resistance to detonation. If you have higher octane, you slow the rate of burn in the cylinder and you hurt power output.

Turbo Blue is leaded. Leaded race gas is poison to your 02 sensors. That's not to say you cant run leaded gas with O2 sensors but it will screw them up. (lots of detail to run leaded with O2 sensors).

So you likely wont gain anything and can hurt parts :D

[AdamantiumSilvr]

...for the heads up. I'm mean if I'm not gonna gain more power and it will hurt performance and will screw my sensors up. Then I think I'll pass on the splash for now.

First, more octane than you need will HURT performance. Octane is effectively a measurement of the resistance to detonation. If you have higher octane, you slow the rate of burn in the cylinder and you hurt power output.

Turbo Blue is leaded. Leaded race gas is poison to your 02 sensors. That's not to say you cant run leaded gas with O2 sensors but it will screw them up. (lots of detail to run leaded with O2 sensors).

So you likely wont gain anything and can hurt parts :D