Aviation fuel for racing

[1969mach1351]

I've always heard of people using aviation fuel for racing. Which octane level is usually used? I can get 100 low lead but is the lead bad for a newer engine? I've heard that it will help lubricate the engine and run cooler but wont it stay in there and gunk it up?

 

[302 coupe]

don't put av fuel in your car, its pointless and can damage any/every rubber piece in the fuel system. With 9.0:1 comp (in your sig) all you should need is 87 or 89, higher octane fuels might actually make you lose power.

 

[D.Hearne]

I used to run it in my 427, but 302's right, with a 9 to 1 comp ratio, you don't need it. Even advancing the timing all the way, you still can't use the extra octane. Higher octane doesn't mean it's a more powerful fuel, it simply means it's got a higher resistence to detonation ( it's harder to ignite)

 

[j69302]

I never had any experience with Avgas damaging any rubber parts. I have ran it several times in my 302, and my dad has put it several times in his 56 thunderbird with the stock 312 and never had a problem, and they actually ran better. I tried Unicals 76's 104 octane racing fuel before, and I didnt notice any difference at all compared to 87.

Keep in mind, aircraft engines dont have high compression ration either. Some of them are as low as 8-8.5 - and these are normally aspirated. I cant recall any off the top of my head that are significantly higher.

The lead was added to help keep things cool and at the same time it increased the octane.

Lead can foul plugs if the engine is ran at low speeds for extended periods of time. Aircraft engine manufactures recommend to run the engine off idle just prior to shutting off an engine to remove any lead that may have accumulated.

100 LL specific weight is different from racing gas and you may possible have to rejet the carb, although I didnt.

100LL is also a more refined and cleaner gas.

But as stated earlier, if you dont have the compression then it wont benefit you much. Higher octane fuels do not have higher heat value thus will not produce more power.


Avgas does make the exhaust smell really sweat though. Not that I sit there and sniff it, just something Ive noticed.

 

[69boss429]

Leave the avgas for the things with wings! If you insist on trying some high octane in your 10.5 or less compression engine,fill it with 100 proof Sunoco,if it makes no difference,go back to 94 pump gas and save some money.

 

[68rustang]

You might as well fill the tank with 87 and every 15-20 miles throw a dollar out the window. You would be getting the same net effect

 

[rbohm]

remember that higher octane actually slows the rate on combustion to prevent detonation. if you dont need the higher octane fuel, dont use it.

 

[HHStang]

I ran it all the time in performance jetski's and had no problem. It smells a bit funny burning as its got antifreezing agents and stuff in it. No problem with rubber either. It's a cheap 100 octane.