Racing fuel = how much power increase?

[Motorhead350]

If everything is correct 428rwhp = around 512.6 to the crank.

How much power should I expect to gain with 100 octane? What settings will I need to change to make sure it runs properly?

Thanks.

[Paul T. Casey]

First part of the question is depends how brave/foolish you want to be. The same answer applies to the second part as the increase in octane will allow you to add timing and remove fuel. For the most power, run about 25 degrees of timing and about a 14.1 : 1 a/f. Do this near the spot you keep your junk, as you will be adding to this pile. (Just kidding, don't use those values). I'm sure the s/c guys here can get you pointed in the right direction, but you may have to pony up for some dyno time with the race fuel to optimize your output.

[FormulaMarauder]

You will actually run slower due to lack of timing unless you get a specific tune for it.

[in2deep]

With 100 octane on an empty fuel tank, you can safely put 5 degrees of timing in (you can add more if you listen for detonation) without a specific tune.
Expect reductions on ET's of .5 seconds or more.

[merc]

You will actually run slower due to lack of timing unless you get a specific tune for it.

That is the correct answer.

Octane rating is defined as the resistance to detonation a fuel has in an internal-combustion engine. The higher the number, the more resistance it has. That is why engines with higher compression require higher-octane fuel. As a result of its resistance to detonation, it has a resistance to burn as well. This resistance to burn is a non-issue in motors tuned to the edge; the edge being just before detonation occurs. When a pump-gas engine is subjected to a higher-octane race fuel, it may result in a decrease in power from an incomplete burn.

Stoich Points of Race Gas

http://www.modularfords.com/forums/showthread.php?t=132628

Ever wonder if your airfuel will change with race gas? The answer is yes....

Real gasoline has various different stoich points due to the blend, how much ethanol is in it, etc. It is somewhere between 14.1 and 14.7 though.

Finding the information on race gas isn't easy. It is not posted anywhere on the internet that I have found. VP does not publish it, nor does Sunoco (TurboBlue)

Several weeks ago I got in touch with the chemist at VP and got all the stoich points of their fuels. Last week I got in touch with a Sunoco chemist and got the data from him as well.

When I asked the guy from Sunoco why they don't publish the information on the TurboBlue website he said -

Quote:
Eric - you're right, stoichiometry is important. Fact is many people have no idea what it is - kudos to you for knowing. Unfortunately many folks we talk to think the stoichiometric air/fuel ratio is where they should set their fuel system at wide open throttle. So we are torn about posting or not posting stoichiometry data because of that potential problem.
Shocking right? Especially when you see how different the fuels are...

Here is a list of the ones I have gathered.

Sunoco MO2X UL – 14.5
Sunoco 260 GTX – 14.4
Sunoco 260 GT – 13.9
Sunoco 260 GT Plus – 13.7
Sunoco Standard – 14.8
Sunoco Supreme – 14.9
Sunoco MO2X – 14.5
Sunoco HCR Plus – 14.8
Sunoco Maximal – 15.0
Sunoco MaxNOS – 14.9


Turbo Blue Unleaded (100 octane): 13.9:1
Turbo Blue Unleaded Plus (104 octane): 13.7:1
Turbo Blue 110: 14.7:1
Turbo Blue Advantage: 14.9:1
Turbo Blue Extreme: 15.0:1


VP Street Blaze 100 = 14.16
VP C10 = 14.53
VP 110 = 15.09 Merc's race tune is set to this measurement.
VP C16 = 14.77
VP MS109 = 13.41

Back to pump gas.... While I had the Sunoco guy's ear, I tried to get an answer about the stoich of their fuel and to find out how much actual Ethanol is in it, when the label says up to 10%...

Here are his comments...

Quote:
I know plenty about pump gas, enough to say that there is no useful stoichiometry data on pump gas. Composition varies WAY too much, regardless of brand/refinery/etc... especially on the lower octane grades.

But I can tell you that Sunoco 94, which is very hard to find these days, will contain some ethanol. Per the first sentence, it will depend on the blend though. I would go out on a limb and say it is nearly 10% most of the time (keep in mind 10% is the max allowed by law).

Street gas blends change all the time thanks to environmental requirements (fed/state/local), seasonal adjustments, and price pressures.
__________________

[juno]

go to kennebell.net and do some research. Lots of good info on Octane-Boost-timing and a lot of other things.

Like the others said, need a tune for more hp.

[Motorhead350]

Yes I knew I had to change the timing, but now I know 5 degrees and maybe lose .5 seconds. That would be great!

[Paul T. Casey]

Yes I knew I had to change the timing, but now I know 5 degrees and maybe lose .5 seconds. That would be great!

I think what was said was you'll loose the .5 if you don't make fuel and timing adjustments.

[Joe Walsh]

Dom!!!

Don't try that Kerosene-Race Gas trick again!...:eek:

;)

[Motorhead350]

Dom!!!

Don't try that Kerosene-Race Gas trick again!...:eek:

;)

It's too soon for a good cleaning like that. I have to wait at least another 20,000 miles. :P

Thanks for the info Paul.

[in2deep]

I think what was said was you'll loose the .5 if you don't make fuel and timing adjustments.

Nope, I meant an ET reduction of .5 seconds (on a SC car) is easily achieved with 5 degrees of timing and 100 octane.
Mod motors LOVE timing!

[Vortech347]

So many varibles.

Good luck in not blowing it up. My suggestion would be to run about a gallon of 100 unleaded to a full tank of 91 Or 93 if you got it.

When I run my stang I only use a gallon of the race gas to help curb detonation a bit and thats all. Unless you've dyno'd and tuned the car with completly straight race gas you're going to run you will likely see not much gain.

[in2deep]

Unless you've dyno'd and tuned the car with completly straight race gas you're going to run you will likely see not much gain.

Simply put, not true.

[Vortech347]

So its okay to throw a whole bunch of timing on an SC'd car with an un-known mix of fuel in the tank? I went with Meth specificly so I wouldn't have to deal with this issue. Its great.

[chader]

when going to a race fuel tune, how do you guys get the low octane fuel out of the tank? Just run it close to empty, or is there a drain someplace ?

[glassman99]

I run 100 until the tank is damn near empty then add C16 and run it for a few miles to get it to the injectors, set the tune to "almost" and let'r run.

[glassman99]

C16 c16 c16 c16