Corey_68

So has anyone ever run Av-Gas in their Vette? I know it's leaded and race fuel is preferred, but a friend has several planes plus two company jets and I can get pretty much get all I want for nothing. What are the pro's and con's of using this stuff verses race fuel in my big block? I was also told to run this fuel with a mixture of Mystery Oil? :confused:

gkull

Not anybody smart! Ag has lots of properties to run at high alt. Vapor point ....... Race gas in blends or alky of the correct ratio is the only thing to do.

rainman69

AvGas BAD! Jet Fuel EVEN MORE BAD! Jet Fuel is Kerosene. AvGas is blended different...it's not a cheapo alternative. It used to be, but not now.

BTW, what big block? How about comp ratio, etc...


[Modified by rainman69, 8:56 PM 2/18/2002]

Corey_68

I'm building a 468 w/ 2.19 iron heads and 10.5 compression. The best we have in Louisiana at the pump is '93(race fuel at the track) so I guess I'll be running some octane booster for the street. :sad:

rainman69

You should not need any boost at that comp ratio. I'm running 11:1 factory pistons, and I have slight detonation without boost and 93 octane. I prefer "Outlaw" that comes in the four bottles for $9.99. I run four tanks with it in and then one without. Works great with 91 octane and 6000' of altitude.

Magnum '82

Don't get caught with it. It is illegal for road use. Your buddy could get his butt in a jam for supplyng it to you too.

Neo Fender

(1) What makes it illegal is that aviation FBOs obviously don't charge the highway and road use taxes that are built in to the price of automotive gas.

(2) More octane is not better, in fact in can be worse. Increasing octane raises the point at which fuel ignites, thus making it more difficult to burn. This is intended to reduce pre-ignition (knocking). If a car runs fine (doesn't knock or ping) with 92 Octane, 100 Octane Low Lead (Av gas) won't help. Think of it this way, if you can run fast wearing size 10 shoes that fit your feet, would size 13 shoes make you run faster?

(3) Av-gas is currently running over $2.00 a gallon. There has to be a cheaper way to raise octane if needed.

Lt1er

Thad build your motor with very near to .040 quench area. Buy a cam made for your compression ratio. Get your dist. recourved to not have full mechanical advance till 3000 rpm. Use an adjustable vacuum advance can. ensure you have a good radiator and 180 thermostat

Then 93 octane will work fine. I have a small block with @ 10.5.

Top_Notch

It also has different specific gravity, so you would have to reject
to take any advantage from it. Some also attack rubber lines.

Wrencher

When gas first went to h***, I had the wrong cam in my BOSS 302 for the poor grade fuel, so I'd mix in 20% leaded avgas per tank. After freshening up the engine and a cam change, it was no longer a problem. Worked for me, but it is illegal to run :D. Now I can buy racegas when I need it.

Hans