A question for aviators and progesssive thinkers- Av-Gas

OK I no doubt spelled that wrong it may not be AV-gas but I am thinking about aviation fuel like you get at the airport for your little internal combustion engined air plane.

Now before we get started this is not a discussion about E-85 at the gas station, so please start a new thread if you want to talk about E-85.

On to my question, when I was a kid they said that you could not run aviation fuel in your car because it burned too hot. I have always thought that was an Urban legend but I have never put it to the test. So can you run Aviation fuel or a mix of aviation fuel and pump gas in your engine to get higher octane?

The reason I am asking is that I may someday want to run a high compression engine (like around 12:1) and it occurs to me that every podunk town in the nation has a little air port so it would be redily available for a rod trip.

Lets get some dialog going here. Aviation fuel as a mix or straight.

 

AV gas has a high level of aromatics which can contribute to lazy throttle response.
even though it has higher octane levels..it also has a specific gravity different than automotive fuels

it may work well in high compression engines, but not really deliver enough bang for the buck spent on the more expensive AV-fuel..trade off if you will

http://www.osbornauto.com/racing/race2avgas.htm

 

AvGas is 100 ll "low lead" It is an old wives tale that it will burn your engine up, The only problem I have run into with using it in a car engine is that the gravity is different than car gas and will not lift the floats in a Holley carb to seat and will flood it I did put a set of heavier springs on the float shaft that were on my airboat "Holly 500" and cured the problem "I have not tried a Rochester or carter/weber etc." It does run good in my ot 77 F250 and have not had any ill effects. It will destroy a catalytic converter not that they would be on a Hotrod anyway.
Avgas has a cooling agent in it to keep the cylinders from getting too hot, Ater 25 years of building airboats I have seen the effects of running car gas in an aircooled engine. Cylinder heads cracked and valve seats dropped out etc. I figure you might be safe to 11:1 but that might be the threshold. And run it straight! Smells good too!

 

Many of these "podunk towns" with little airports do not sell av gas for non aviation use. If you find one to sell to you that's great. Av gas per gallon at my airport is $6.75 a gallon and it's $7.50 a gallon and up at the larger airports. You might as well buy VP C12 or the equivelant. I don't know the going price of racing gas but it will work better for what you want over 100LL aviation fuel.

 

Usually I stand back and let other people complete discussions like this however somethings in the above statement are not true. Av gas has a different specific gravity and does require re-jetting however there are other chemicals in it called bromides that are designed to increase the combustion temperatures to get the lead out of the combustion chambers. 100 low lead is loaded with lead to lubricate the valve seats and will foul plugs if the temperature are not kept high enough. Aircraft engines are kept cool by airflow, oil coolers, and using the fuel mixture (rich mixture runs cooler lean higher up to a point). There are lots of aircraft that are able to use auto gas. The ethanol in the gas is a no-no. There are things called supplemental type certificates that spell out exactly what gas can be used and with what types of engines. We use av gas that is drained from the fuel farm every morning to gas up the ground support equipment and it is hell on carbs because the jets get worn out. Use it at your own risk.

 

Back when I ran gas in my drag car, it was av gas. I run alchohol now and have since 96. I think I jetted slightly richer,(CRS) but had no problems whatsoever. Compression was 13.1.

Some now tell me that they wont sell to you at the local airport.

 

Also to buy AV gas the airport is required by law to have the registration number of the aircraft for their paperwork. Something about road taxes.

 

if the floats would not float because the gravity is different..how did putting a heavier spring on them make it easier for the low specific gravity fuel to lift a float that now has an even heavier spring on them

granted...the AV fuel has a spcific gravity different from auto fuel, but you just made it work against a stiffer spring?

am i missing something here?

 

The jets get worn out?????

 

This is true..
but if you are a pilot, and owner..you can work this out
as long as the amount of fuel doesnt raise red flags

 

PNB, please dont do it. Get yourself an adequate octane race fuel, buy it by the 5 gallon container, or spring for a 55 gal., if you can. The other alternative is how many have been doing it for years, good name brand Octane Booster in a can and a precise way to measure, and keep it in the car with you. Google race fuels, or just go to the local drag strip and you find someone/dealer selling Torco, or Sunoco or the V.P. race fuel.

 

The tiny little holes in them do get larger with the amount of fuel the line guys burn. They go thru carbs every few years. More than likely not an issue that most people see.

 

The spring is pulling the float towards the closed position.
This is done on off-road vehicles too,so the floats have less tendency to bounce and cause flooding.

 

Mid 90's I used av-gas in my 11 second 64 Vette drag/street car. One day i decided to try some nitrous on it and blew a head gasket. So, after removing the head with barely 1000 miles on the motor, there was quite a bit of JB Weld looking buildup on the stem of all the intake valves in the area between the head of the valve and the valve guide area (where the fuel air travels from intake to combustion chamber). I believe at the time my neighbor, who'd wrote a paper on fuels in college mentioned some sort of anti-freeze component in av-gas to deal with the real low temps at higher altitudes may have been the reason

 

I raced on AvGas for a couple of years.

My car wouldn't run on pumpgas ( 11:1), and it wasnt as expensive as racing gas.

Like Groucho says, they do something to it to make it cope with the cold temps at altitude.

Same kind of stuff they do to the pumpgas they sell in the winter, which I'm told is different from the gas that is sold in the summer.

 

Av gas does not wear out jets it is no more abrasive than automotive formulated fuel. Ran it in racing outboards as a cheap alternative to race gas; run about 5% richer jets to compensate for the specific gravity difference. It does not have enough octane for ultra high compression or nitrous motors however.

 

I have a 472 c.i. early hemi supercharged making 16 pounds of boost. I din't want to spend $10.00 a gallon on race gas so I mixed my own blend. I use 92 octane and for every gallon of gas I use 4 oz. of alcohol. I also use some Marvels Mystry oil.

 

Just talked to one of my old customers. The hot ticket right now is this stuff from Torco called Accelerator. This is what I will be using when I step up the 26 with the new heads I'm prepping. Again the key to sucessfully blending your own is a presise way to measure, you wont have any problems there I'm sure.

 

There are always lots of things to do to a racecar before every race.

So I didnt want to mess with any kind of aditives or make my own blends out of different kinds of gas.

I did not need something else that was going to cost any time, or create something extra that could go wrong incase the mix was off for some reason.

I just ran straight AvGas...

 

I was just curious if it would work. Somewhere I got this crazy idea in my head that whatever I own should be ready to go cross country whenever the need arises.

Anyway the other day I was cruising past an air port on my way out to our place up north (just about 10 miles past pig snarf). It occured to me that there are little air ports/air strips everywhere, I was just wondering if it is a viable option.

It never occured to me that you had to own an airplane to buy fuel. That pretty much nixes it even if it is doable otherwise.

 

I run it in my lotus 7 with no problems, seems to run better than standard fuel, have to tell them i am running it in my jet boat (no road user taxs for boats) they used to have a tanker at the local race track when all the classics where out . it seemed to be all they ran
the only thing about buying it here is the price and the fact you have to pick up in a container(you can't pump straight into a car)

 

You nailed it!

Very few airports are going to sell the stuff, especially to a total stranger. They could get in serious trouble with the federal government. The feds don't appreciate:

(A) the lead (even the low level currently in av-gas)
(B) the lack of road taxes on av-gas

The other issues can be overcome.

Jon.

 

I remember back in 1977 I had a '67 Nova SS with a 327 with 11 to 1 cr. and I used to go out to the local grass airfield and put 5 gallons in the tank with the Premium gas...ran great! You could really feel the difference. The old man that ran the airfield had an honor system...you pumped the gas yourself and put your money in a little tin box on the pump...really.

 

Von,,,
Yes I have experience in the field of aircraft engine modification to land use and i wouldnt have posted If I didnt,,,,. A gentleman asked about AV-Gas ad I replied! and yes I had to add a specific spring to not have the 4 lbs of psi not blow past my seat using AV-Gas on A 500CFM Holley 2V
MUAH!

 

MMMmm K man

just sounded a bit counter intuative, learn somethin new everyday.

 

everyone i knew that ran it loved it. everybody went to the airport on saturday to fill up before the sat night street races, no problems

 

Back in the 60s i would "appropriate" 115/145 from the flight line to run in a couple of B dragsters in Bakersfield.Helped a bunch,one time we didnt have enough money between the three of us to get back to the base,so we dumped the Av-gas in the tank of my 60 chevy.Made it to the base(100 miles ) ok but my tailpipe was pure white,but no damage.Guess we were lucky.

 

Pork,

I built my engine to 11:1, maybe a tad more. I'm setting up to run LPG. You can buy it almost anywhere, 105 octane.

Give me a shout and I'll be glad to get on the phone and spill everything I know about it, just to muddy the water a little more.

 

I have used 100LL on occasion. At least in California you can't legally buy it for street driven cars because of the fuel tax normally charged to cover road repair. Of course in California that money goes somewhere else anyway, but it's the law. Race cars do not drive on the street and are not required to pay gas tax. Compared to ERC 110 race gas I had to run about 5 richer on the bypass, with 100LL, to make up for the lower specific gravity of the Av Gas. Same volume, less weight, less energy. You will never burn up any car motor burning aviation gas.

 

Back in high school there was a private air strip for all of the local crop dusters a few miles outside of town. They'd sell us the Avgas (100LL) that we called "Blue Gas". A couple of us guys would get about 20 gallons and then divide it up and pour it into the tanks of our street cars, mixed with regular pump gas. I never noticed a real difference in my own car, but back then it was just a 13 second car so it didn't really need the added octane. It ran fine, never had any issues with running that fuel, and as far as I can remember, neither did any of my friends.