aviation gas/race gas

[bordrshane]

I ran av gas (airplane fuel) at Mammoth MX several years ago when I used to race. Sometimes Ill run it in my honda 50 but those little hondas are bullet proof. I just got a used 2000 yz 125 and the head has been milled, cylinder has been ported. What do you guys think about running av gas instead of race gas? Race gas is hard on the wallet and av gas is just a few bucks a gallon. I hear av gas is around 100 octane is why Im asking. Thanks

 

[Okiewan]

See the search button up there ^^^
Type in Avgas.

 

[robwbright]

I'm in the middle of this decision as well. I have used Avgas since I got my RM in May. Its a stock motor and the avgas works pretty well. Anyway, I finally found race gas nearby for about $4.25/gal. AVgas is $3.50+/-. I'm about to spend $450.00 on my motor, and apparently I'll get an extra hp or so with the race gas. I think I'm gonna go with the race gas.

Check out Rich's articles:

http://dirtrider.net/forums3/showthread.php?t=115202

http://www.ericgorr.com/techarticles/Fuel_Basics.htm

With my posts here, I've learned that octane is far from the only factor.

Anyway, to quote Rich:

In almost every case 100ll Avgas is a better choice than alcohol pump fuels

- If you don't need the additional octane that 100LL provides, then MTBE based pump premium (especially Amoco) will tend to provide better throttle than Avgas assuming you have any jetting skill. If you can't jet you're just wasting your time worrying about any of this stuff on a stock bike.

- Mixing 100LL Avgas with a good race gas designed for your application and rpm range is a reasonable way to save some money.

 

[Bullwinkle58]

Avgas is cleaner burning than pump gas. Less deposits on your piston & cylinder head; you won't have any to speak of if you use a clean-burning premix.

 

[Masterphil]

Avgas is cleaner burning than pump gas. Less deposits on your piston & cylinder head; you won't have any to speak of if you use a clean-burning premix.

Yessa Massa, whatever you say :coocoo:

 

[DLHamblin]

Avgas is cleaner burning than pump gas. Less deposits on your piston & cylinder head; you won't have any to speak of if you use a clean-burning premix.

Except it has a LOT more lead than any leaded car or race fuel. Bikes normally run hot enough to burn it off but when we overhauled our Cessna (airplane) engne, I was amazed at how much lead deposits had built up under the piston crowns and parts of the crank. :ohmy:

I personally won't use it because of the high lead content and the fact other than its 100 octane I don't see where its better. Its formulated for slow rpm low compression engines? Perhaps mixed with race gas it helps lower cost, but thats about all I can see (except the smell, I like the smell of AVgas out the exhaust...)

 

[Rich Rohrich]

Except it has a LOT more lead than any leaded car or race fuel.

Current 100 LL generally has 2 grams or less of lead per gallon. Modern race fuels have 4-6 grams per gallon.

There isn't enough lead in 100LL AvGas to cause any issues.

 

[mtk]

Which is why the "LL" in the name stands for "low lead." ;)

 

[njrealtor55]

my 2 cents...

av gas is better quality than most of the pump gas you will find out there.

If you race, run race gas. If you rec ride - av gas is just fine.. most rec riders do not run thier engines as hard as racers do.

This is almost the same as issues of top end rebuilds - it all depends on how hard you run your engine. If you can honestly say you stay on the pipe and accel hard the whole track - then run race gas..

Lucky for me I can get CAM2 100 octane at the local gas station - although i would have no issues about using avgas. If the CAM2 was not available, I'd use avgas.

Some may say the costs are different, but I only use 5 gallons max for a weekend - so technically the fuel cost is minimal - especially compared to when i race jetskis in the summer (15+ gallons of 112 octane @ $7/gallon per weekend)

 

[DLHamblin]

Current 100 LL generally has 2 grams or less of lead per gallon. Modern race fuels have 4-6 grams per gallon.

There isn't enough lead in 100LL AvGas to cause any issues.

Depends on "how much" is a concern, 100LL has 2.0 grams per gallon, the old 80/87LL av gas had 0.5 grams per gallon, and good old leaded car gas had 0.1 grams.

I am surprised they even allow race gas to have 4-6 grams per gallon.

 

[DLHamblin]

Which is why the "LL" in the name stands for "low lead." ;)

Its relative, 100LL has 4 times the lead of the 80/87LL av gas it replaced.... So while its lower lead content than the old 100/130 av gas (4 grams per gallon)its definitely not "low lead".

 

[BonChance13]

how many times are we gonna beat this horse?

 

[DLHamblin]

how many times are we gonna beat this horse?

Ranks up there with which is better, 2 or 4 stroke MX bike. :laugh:

 

[yammie rider]

just curious where to get aviation gas at?

 

[Rich Rohrich]

Depends on "how much" is a concern, 100LL has 2.0 grams per gallon, the old 80/87LL av gas had 0.5 grams per gallon, and good old leaded car gas had 0.1 grams.

I'm not sure where you got your numbers from but according ASTM D4814-93 , "good old leaded car gas" was allowed up to 4.2 grams of lead per US gallon, and most of the good fuels took full advantage of it. Even US spec unleaded gasoline is allowed up to .05 gram/gallon. Which is sort of funny seeing as how the AMA Pro Racing limit is lower, which could conceivably make pump fuel illegal in a Pro MX race. :coocoo:

There are lots of very good reasons not to use AvGas but I don't personally see lead being one of them. ;)

 

[bordrshane]

Ok..............

What a response. Sorry I didnt do a search first. I realize I hardly even ride anymore, so spending an extra 20 on race gas is no big deal. Cant go wrong with something thats been proven. Ive come to my own conclusion that avgas is designed by engineers who have developed it for high altitudes (less oxygen), and a constant rpm. Im not a chemist, but what is developed for up there and runs at a constant rpm probable wont work as well in my bike as something that was developed for it.

 

[Rcannon]

just curious where to get aviation gas at?

My guess would be somewhere near an airport. Personally, I have trouble finding it. I live where the National Guard flies helicopters. Maybe I need to start a thread about helicopter fuel?

 

[DLHamblin]

I'm not sure where you got your numbers from but according ASTM D4814-93 , "good old leaded car gas" was allowed up to 4.2 grams of lead per US gallon, and most of the good fuels took full advantage of it. Even US spec unleaded gasoline is allowed up to .05 gram/gallon. Which is sort of funny seeing as how the AMA Pro Racing limit is lower, which could conceivably make pump fuel illegal in a Pro MX race. :coocoo:

There are lots of very good reasons not to use AvGas but I don't personally see lead being one of them. ;)

They were allowed up to 4.3 grams I think till the early '70's; I got my numbers from the EPA website. While that was permitted, from the 50's to late 60's (or when the new law took affect) they said the average was around 2.4.

Its like the 2-4 stroke thing; everyone has to make their own choice.

 

[DLHamblin]

My guess would be somewhere near an airport. Personally, I have trouble finding it. I live where the National Guard flies helicopters. Maybe I need to start a thread about helicopter fuel?

Unless things have changed (or you know somebody) they aren't supposed to sell av gas at an airport unless its going into an airplane (legally; but in practice its who you know).

One air port we were at didn't like to pump av-gas into containers, only airplanes (even though we were based there and they could watch us walk down the ramp and dump it in the Cessna!) So, we would have to start up, taxi down, shut down (you get the picture...)

So it really depends where you are getting it from.

 

[Faded]

Unless things have changed (or you know somebody) they aren't supposed to sell av gas at an airport unless its going into an airplane (legally; but in practice its who you know).

LOL, things must have changed because around here some white kid off the street with a big red can in one hand and some dollar bills in another can drive to any local airport and get Chevron 100LL regardless of who you know.

 

[robwbright]

LOL, things must have changed because around here some white kid off the street with a big red can in one hand and some dollar bills in another can drive to any local airport and get Chevron 100LL regardless of who you know.

Same here. SE Ohio.