jlutherva

Are 100 Low Lead race gas and 100 Low Lead aviation fuel the same? Aviation fuel is about $4.50 and race fuel is about $9.00

Jim

D K

E85 is $2.05

63Corvette

It depends
On mostly your (dynamic) compression ratio. Aviation 100LL is um....100 octane. The very high octane stuff for your P-51 is mostly unavailable. So, up to about 11:1 or so with a stock iron head small block Chevy, the 100LL will work. BUT....for RACE engines with 13:1 to (Duntov) 15:1 compression ratio you will need to use at least the VP highest octane gas available.

SouthernSon

Jim, Low Lead aviation fuel is not 'low' compared to automobile engines. The LL has 4 times the amount of lead as the leaded gasoline of days gone bye. Many times my Mooney would get lead fouling on the fine wire spark plugs. Aviation and Autos don't cross reference.

BTW, it would not be wise to be caught ferrying green or blue dyed fuel away from the airport. just sayin'....

juanvaldez

Really! I fill gas cans at the airport regularly.

jpb1978

Yes, but as SouthernSon points out, it is illegal for both you and the airport operator. I did it a few times at an airport where I kept my plane but the airport owner told me he did not like it and to stop.

jlutherva

Well, right now, I'm running 11.5:1 with O2 sensors and a fairly conservative tune on a forged motor. I run 93 pump gas with a 20% mix of 100 octane no lead. It's just kind of a PITA to find the 100 no lead and mix it. It sounded like an easy way out..... I'll just stay with what I'm doing now.

Thanks for the responses!

Jim

Joshboody

You'll get more octane with an E35 mix than 100oct gasoline.

Kubs

I have about 11.3:1 compression in my old school small block C4 race car. I was getting knock counts under load at high RPM on 93 pump gas alone. I now use 25% E85 mixed with the 93 octane which comes out to about 96-97 octane and no knock. Like mentioned E85 is also much cheaper than race fuel and can be found fairly easily in most cities. The only difference is you will have to add about 6-8% more fuel in your tune. since the alcohol is less efficient.

juanvaldez

Many/most airports have self-serve 100 LL pumps. I have never seen a sign saying using it in something other than an airplane is illegal. It has always be dyed to identify the octane visually. The only thing that comes to mind is that it doesn't have road tax. Neither does race fuel.

96CollectorSport

We ran 100LL on our LS powered track cars for years with no issues, I think they can be tough on O2 sensors, I found that if you replace a failed O2 sensor with a brand new one that it failed quicker than if I installed a used one.

As far as the legality of running the 100LL my thoughts are that as long as the car isn't run on public roads then why the heck would anyone care? The road tax paid on traditional gasoline would not apply here since you are using the fuel for a hobby like flying - I guess it comes down to the individual officer some are more by the book than others. In most areas they have bigger issues than someone buying gas at an airport and putting it into there race car.

Our prepared "story" if we were asked about the fuel leaving the airport was that we were finishing up a "superlite" and needed the fuel to fire it up.

SouthernSon

Thanks. You try to help folks out with some information and some little smart alec has to throw in their two cents (worth less than a penny).

Another good reason or two not use the aviation fuel:

http://www.rockettbrand.com/download...s.%20AvGas.pdf

VetteDrmr

O2 sensors and aviation 100LL don't play well together; one of the (very many) reasons holding back closed loop fuel injection systems from aviation.

HTH, and have a good one,
Mike

JHrinsin

Exactly!

maj75

My ‘69 427 don’t have no stinking O2 sensors and is very happy on AvGas.

VetteDrmr

Yep, I bet it is. 100LL still has a lot of TEL in it; don't know what CR you're running, but unless it's pretty high you might have lead building up on the exhaust valves/seats and maybe the combustion chamber.

HTH, and have a good one,
Mike

maj75

I hope so, since they are the original un-hardened seats.

VetteDrmr

SouthernSon

Jim, here is another article that explains the dynamic a little more indepth.

http://www.dragracingpinoy.com/artic...-vs-racing-gas