premium gas for pulling

[Old Mo Iron]

I was curious of the different fuels being used in pulling, I read about how pullers where using ethanol instead of say (race) fuels. Wondering what other pullers was using I know it has alot to do with compression but your average overbore flattop, what would be the best way to go? I have always used premium with a little mixing, but ethanol is cheaper.

 

[north puller]

As you mix in ethanol, your overall octane rating goes up. (Pure ethanol has an octane rating of 116).

A typical M&W piston set should work fine on regular grade fuel, or at the most, mid grade.

I have never tried it myself, but I have been told that you can get a small power gain by using 25% ethanol and it won't be to hard to tune.

I would think that a 50/50 mix of E99 ethanol and 100LL avgas would support some big compression and be a reasonably inexpensive fuel.

 

[toolz]

You may already know, but just to clarify, higher octane fuel does not make more power. The only reason to use it is to supress pre-ignition, or knocking, in a high compression motor. The best power will be made by using the lowest octane fuel that the motor will put up with. Higher octane fuel burns slower, which is why it doesn't pre-ignite as easy. If all else stays the same, switching to high octane fuel will cause the motor to run lean, due to the slower burn. If it improves power, it was running too rich to begin with. Of course, some additional power can be found by advancing the timing (within reason) and that may create the need for higher octane fuel to control pre-ignition.

 

[mightymolinekid]

I do believe toolz is mistaken on a couple of points. Most race fuels like Sunoco standard and such, actually burn faster than regular gasoline. The reason it doesn't pre-ignite at the same time regular gas does is because it has a higher flash point. That is, it ignites at a higher temperature. By using the lowest grade possible, you might be missing out on some of the additives that higher grade gas offers, also most race fuels are leaded. I personally will never run ethanol, or any blend because it's crap fuel that burns quite a bit hotter than straight gasoline, which burns hotter than race fuel. Try to find premium gas without ethanol if you can.

 

[DCPULLER]

toolz is correct. High compresion makes heat which pre ignites lower octane fuel. It takes more to ignite race fuel. Dave S

 

[Clint Skarovsky]

I'm with Toolz.........if you don't have enough compression to need the detonation resistance of the higher octane you're likely giving up some power.

 

[roger kosharek]

i burn shell premium gas in mine

 

[north puller]

I don't know the combustion temp of ethanol when it burns, but an engine running on alcohol will run colder than one on gas due to the refrigeration properties and the heat required to vaporize the fuel.

 

[gtx1967jewison]

Any alcohol fuel burns cooler than any pure gasoline. This is a fact. And it has a much higher octane. This is why it requires more gallons to make same power. It contains less btu per gallon which is heat.

 

[Anonymous-0]

Race fuel does burn slower and cooler. It does make more power because of this. Its s'more controlled burn which in turn expands longer and farther putting more pressure on the piston for a longer period of time. But if you don't have the air flow and compression to take advantage of that then its a waist of time and money.

 

[Charles E. McNelly]

I know of several people running a 50/50 mixture of E85 and premium gas.
Charles

 

[Old Mo Iron]

In response to the ethanol fuel. I tried it it didnt work out so well had to have choke half out to idle,
As others stated it must took more of it to burn. So I mixed it with 91 and seemed to pull power away. Im draining, and putting it in my old brush tractor see how it likes it.

 

[ohio]

Good post, Mr. wizard. Read a book.