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Author Topic:   AV GAS????
J3
Dirt Maniac

Total posts: 188
posted February 18, 2005 07:08 PM  
Can someone help me out here. Have a 351W with a few bells and whistles. 11:1 compression. Did some checking on several things and have been told that I need to run 100 octane. I can get 110 octane racing fuel, but that cost over 5 bucks a gallon. I could mix 50/50 with 91 octane to cut that cost some, however, AVGAS is 100 octane and only cost 2.25 a gallon. Cost wise, that would be much better than pure 110 or 50/50 mix with 110 and 91. Are there any advantages to using AVGAS and more importantly are there any disadvantages to using AVGAS?

rfb320
Dirt Maniac

Total posts: 150
posted February 18, 2005 07:17 PM  
There is a post on the forum somewhere recently about av gas and from what was said it should be used for airplanes and not cars. From my own experience I used to run 110 mixed with 91 at 50/50 but after I angle milled my heads and upped the compression to over 12.1 I found that the engine ran better on straight 110. It is more spendy but cheaper than a burnt engine.

racer2
Dirt Freak

Total posts: 352
posted February 19, 2005 06:26 AM  
i ran avgas for 5 years on a 10:5 engine.

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted February 21, 2005 05:50 AM  
There was an article in either circle track or speedway illustrated (cant remember for sure) this month about this topic. There reccomendation dont use AV gas for racing. Basically it says AV gas is designed for high altituds and low rpms. Race gas is designed for low altituds and high rpms and the octane of AVgas is rated different than gas for race or pump gas. It amazes me that people will put so much money into their car and engines yet try to cut corners on something like fuel.

If it were me Id use the 50/50 mix or find a place that is selling something closer to 100 octane. I think Sunoco sells one and VP might as well.

just my opinion.....

TEAMPCR
Dirt Freak

Total posts: 238
posted February 21, 2005 06:05 AM  
If you have hardened exhaust seats, you can use Sunoco GT100. It is unleaded, 100 octane. Usually some cheaper than 110. It is also street legal and has no dye in it.

smallrock98
Dirt Forum Racer

Total posts: 100
posted February 22, 2005 01:45 AM  
Dont use AV gas!!!! Junk Junk Junk! Believe me, I went through this entire episode before. Do a search in the archives on this topic and you can find all about mine and others experiences. One thing I can tell you, using it equaled no power at all. OMG, I can still remember going down the straight and everyone blowing by me. Switched the gas and then I was the one blowing by everyone. Your best bet is just to mix premium gas with the 110 racing fuel. You are at 11 to 1 so I am betting you could actually get away with mixing 1/3 the amount of 110 with the premium.

[This message has been edited by smallrock98 (edited February 22, 2005).]

[This message has been edited by smallrock98 (edited February 22, 2005).]

locorace27
Dirt Roller

Total posts: 14
posted February 24, 2005 02:30 AM  
J3, I have used LL100 Av Gas in my Modifieds for years.
Many different engine configurations , but all around the 11.5 to 1 range.

I began using Av Gas because a small airline sponsor was giving it to me for free.
While free fuel is great, like you , I started to wonder about the pro's and con's of using Av Gas in a race car.
I researched the **** out of it and this is what I found ;
100 octane low lead fuel is designed for aircraft with low compression , low reving engines which produce high H.P.

However, being an aircraft fuel it has the highest quality control - ( a car with a dead engine merely pulls over , an aircraft ...)

The fuel is a "simple" blend just like 'race gas', but way cheaper.

Av Gas is very dry and the use of a lead lubricant can prevent sticking the stems of the intake valves in the guides.
Performance in any average 500 H.P. motor is not noticed.
Actually, Chevron 94 outperforms VP 110 on the dyno.
So use Av, but give it some lube .



dirtbuster
Dirt Forum Champ
Total posts: 2007
posted February 24, 2005 07:43 AM  
"100 octane low lead fuel is designed for aircraft with low compression , low reving engines which produce high H.P."

That line to me is enough of a reason not to use, besides everythign else. While some race engines may be low compression most are not low revving.

J3
Dirt Maniac

Total posts: 188
posted February 24, 2005 12:22 PM  
Well, just what is considered "Low Reeving" for an aircraft? I only turn my engine to 6K. Thanks for all the info guys.
J3

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted February 24, 2005 01:56 PM  
I dont know for sure but I am gonna guess its well below 6000. Something like 3000-3500 maybe, but jsut a guess. In the end though, why buy a fuel designed for a different purpose, and have to throw in some additives or whatever, when you can buy a fuel that was designed for the purpose you are using it for. Pump gas was designed for low compression, low revving street engines, you dont use that in a race engine either do you? Race gas was designed for race engines, higher compression, higher revving etc.


Think about this...Is it really going to cost you that much more for actual race gas... In our mod we burn maybe 8 gallons a night at the very most. Thats hot laps, heat race and feature. Say you save 2$(if that even) a gallon thats only 16$ at most a night in savings. Not worth it to me to mess with trying to make AVgas work instead of buying race gas.


locorace27
Dirt Roller

Total posts: 14
posted February 26, 2005 02:52 AM  
Dirtbuster, you are absolutely right !
If all things are equal, then by all means use a quality race fuel that was designed for the type of engine you're running.
However, there are many situations where the cost of race gas v.s. av gas becomes an issue depending on the class level.
The point being is that racers should not consider av gas as an equal replacement for the fuel which a Cup car may run, but it is also not something to avoid for lower levels.
As an aircraft fuel, the quality control is second to none. The fact that it is used by low compression, low reving motors is nothing more than a timing issue to address the rate of burn.
In a race motor the higher revs do produce less cooling time, hence the lead ad for the stems. (it is low lead after all.)
Plus, Chevrons '94 with Tecron' is as good as most so called race fuels .

Raz_900
Dirt Forum Champ
Total posts: 635
posted February 26, 2005 01:40 PM  
quote:
Originally posted by dirtbuster:
I dont know for sure but I am gonna guess its well below 6000. Something like 3000-3500 maybe, but jsut a guess. In the end though, why buy a fuel designed for a different purpose, and have to throw in some additives or whatever, when you can buy a fuel that was designed for the purpose you are using it for. Pump gas was designed for low compression, low revving street engines, you dont use that in a race engine either do you? Race gas was designed for race engines, higher compression, higher revving etc.


Think about this...Is it really going to cost you that much more for actual race gas... In our mod we burn maybe 8 gallons a night at the very most. Thats hot laps, heat race and feature. Say you save 2$(if that even) a gallon thats only 16$ at most a night in savings. Not worth it to me to mess with trying to make AVgas work instead of buying race gas.


I agree totally.

I wonder how many people throw perfectly good oil away every week? Rather than throw perfectly good oil away week after week, change it once a month, or run synthetic and change it a couple times a year. By not wasting perfectly good stuff (plugs get wasted alot too), the savings would more than equal the cost of using race fuel.

[This message has been edited by Raz_900 (edited February 26, 2005).]

eenfield
Dirt Maniac

Total posts: 116
posted February 27, 2005 06:16 PM  
Most airplanes cruise in the 2300-2700 rpm range BTW....

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted February 28, 2005 07:18 AM  
Thanks eenfeld, I guess I was a little high, but now I'llknow for next time.

hughes
Dirt Maniac

Total posts: 194
posted March 15, 2005 08:10 PM  
Been racing this mixture for 3 years with no problems and engine is always clean. 5 gallons of AV gas mixed with 8- 12 ounces of motor oil (quarter of a quart) and 8- 12 ounces of Toulene. I cut the bottom out of a old quart of oil. I have a 11.5:1 motor.

mekomod51
Dirt Full Roller

Total posts: 42
posted March 15, 2005 11:19 PM  
I am also wondering about Avgas. The price is cheap even with the additives. The folks selling race fuel in our area are asking $6 a gallon for 110 octane race gas. This is for VP or Sunoco. this is just too high im my humble opinion. If I have to run Avgas to save money until I can get a different brand at a lower price then so be it.
One of the distributors down here selling the Sunoco acting like he was doing me a great service by selling at 6 bucks a gallon, get a clue.
needless to say I have talked to others that are buying different brands of 110 or 105 and are not paying 6 bucks a gallon.

I have also talked to several racers that are paying less than 3 bucks a gal for the Avgas and mixing additives to make it work without issue.
Yes racing gas would be better, but at 6 bucks a gallon i can see why others would want to run Avgas.

sidebiteu259
Dirt Full Roller

Total posts: 56
posted March 16, 2005 08:39 PM  
Here is is 5 bucks a gallon. but 225 a drum so i just went with the drum. Av Gas you have to mix this that and what happens if it isnt mixed correctly and you burn down a motor. Im sorry I didnt cut corners putting good parts in a motor to cut coners in the end and watch it become a paper weight. Another point if you mix and match new batches every week you have match the timing to make up for the octanerating being different each time. Pumping it out of a barrel would be better than try to mix it correctly.

[This message has been edited by sidebiteu259 (edited March 16, 2005).]

mekomod51
Dirt Full Roller

Total posts: 42
posted March 17, 2005 02:05 AM  
you make good points however I am talking to several racers paying 4 bucks for the same 110 gas sounds like the distrubutors are playing games, I will find a drum at that price or less.

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted March 17, 2005 07:42 AM  
If you can swing the initial cost of the drum that is far better anyway. Besides being cheaper per gallon when you get a factory sealed drum you know what is in it. IF you buy at the track or somewhere else for that matter you have to trust that the fuel in that barrel is actually the fuel that you want and hasnt been cut down with pump gas or something.

mekomod51
Dirt Full Roller

Total posts: 42
posted March 17, 2005 06:52 PM  
Fuel found for 4 bucks a gal. and little cheaper by the drum. As it turns out down here we only have a couple of suppliers that are well known and they are both charging 6 bucks a gal for 110.
I found a racer selling union 76 110 for 4 bucks and even less by the drum. So I will probably stay away from the Avgas for the time being.

dan murray
Dirt Full Roller

Total posts: 34
posted March 19, 2005 11:53 PM  
Yeah you are definately going to make more power blending your own- I'd mix the 110 race fuel with 50% pump gas premium. The pump gas is oxygenated and will boost hp and torque levels to a slight degree for engines 11:1 and lower. I personally wouldn't want to run anything but pure 108-111 octane for any engine over 11:1 though. Used to use AV GAS but after checking the SPECIFIC GRAVITY comparisons of that and automotive fuel you will clearly see why you wouldn't want to use it unless you were not concerned about getting the most out of your motor or just plain don't have the budget to do the 50/50 race fuel/pump fuel blend. Specific Gravity value of the AV gas is it's worst demise. Hope this helps ya.

graham jackson
Dirt Full Roller

Total posts: 42
posted March 20, 2005 06:06 PM  
We ran the 110 race gas with 50% mix of Avgas LL100 and so far so good.
We paid 4.50 a gal for the race gas and 3.25 a gal for the Avgas, with the 50/50 mis we should still be above 100 octane.

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