av gas

north puller · Nov 15, 2012

What's the real deal with av gas?

I have run some in my tractor and I worked out well. I found that it runs a little bit leaner than regular gas.

I know that it is leaded and has aprox 100 octane.

I think that to prevent vapour lock it doesn't vapourize as eaisly as regular gas.

Some say that it runs very dry.

Some say it is a good fuel to run, and some say that it is garbage.

Just wondering, is the vapourization characteristic good or bad? How much lead does it really contain and is that good or bad? How lean does it really run? How dry does it really run?

What's the difference between av gas lean/rich knock index and gasoline's octane rating?

Av gas is a cheap fuel, but is it any good to use? Is it any worse for deposits than any other leaded fuel? Are there any other reasons that av gas would not be a good fuel to use?

Ole Johnny · Nov 15, 2012

I will explain it like this. They use it in air planes IN THE AIR with NO PLACE TO PULL OVER and work on it. It is VERY VERY good fuel and at 100 octain and low led, it is MUCH better on tractor engines and high horsepower engines than ANY pump fuel you can find.

buickanddeere · Nov 15, 2012

Being scared of 100LL for no reason seems to be the worst problem.
It's fairly high octane and very clean. Run it or any other fuel a little rich for extra detonation resistance.

Anonymous-0 · Nov 15, 2012

dyno it. then, put it back on gas n see how much power you can lose with av gas. ive seen it cost a close to stock M farmall,, 10hp! yea, it ran great till under power she just dies quicker. some can gain, some will not.

51JDAinPA · Nov 15, 2012

He"s got one thing right. They use it in the air with no place to pull over. And unless the track you are pulling on is at 10,000 feet of elevation you are shooting yourself in the foot. Our A that is mildly built lost 15 horsepower on the dyno compared to premium 93 octane with TORCO fuel additive. Aviation gas just plain isn"t made for low elevations. Thats why they use at high elevation where air is thinner and NOT on the track...

LarryM · Nov 15, 2012

All that matters is what the Dyno says. Without testing and verification all you have is an opinion. I have a C-281 engine in a Farmall M that I have been palying with and so far I have achieved results beyond what my expectations were. It is a C-281 engine with stock cam and head and manifold and it comformatic pistons that only create 8:1 compression ratio. I have been playing with different fuels and they range from 63 hp to 69 hp. What I have learned is that people on this site are gracious but the really really good information will not be divulged here. Check out the video.

http://youtu.be/MljPZZJlsSg

Anonymous-0 · Nov 16, 2012

your pump gas must be a bad blend.

RichB · Nov 16, 2012

What is the specific gravity of this AV gas? just curious.I use C12 in my Oliver and thats the least amount of octane I can get away with...But it ain't cheap stuff!

LarryM · Nov 16, 2012

I was going to type a long post here but then I remembered who you are.

LarryM · Nov 16, 2012

I was going to type a long post here but then I remembered who you are.

Anonymous-0 · Nov 16, 2012

lol. please, dont let that stop you....... go ahead, type it out. ive been there, done that, and the real proof would be that the av gas is def better than what you get at your pumps. I cant say that here. thats why it was said, sometimes it works, sometimes it dont.

Anonymous-0 · Nov 16, 2012

but it costs horsepower...apparently i'm not the only one who has seen it on the dyno as others are posting it in this thread. it's not a good gas, it's a GREAT gas, but it won't produce as much horsepower as other gasses will.
At the end of the day, the lowest octane your motor will run on without knocking or pinging will generally give you the most power, as long as you're comparing good quality gasses. some of the pump gasses are so full of ethanol and other add ins that even though they may be all the octane you need, they don't produce as much power because they don't burn as well.

LarryM · Nov 16, 2012

Nah, People who throw out negative comments without substantiation are not worth my time.

Bouncer · Nov 16, 2012

So are you the pot or the kettle then?

Anonymous-0 · Nov 16, 2012

Wheres the negativity? seems to me like your shoulders chipped a lil bit more by being pissy. who says things like that? im not attackin ya dude! all i said is, its obvious your pump gas sucks and i belive you when u say you gained power from av gas over your pump gas. ive seen it 500times! Some places in the USA, have very crappy gasoline. Some places have very good pump gas that will make more power than av gas. i am not by anymeans, cutting you down. so quit that bullcrap blaming me for unsubstantiated claims. ive got 25yrs in antique pulling and LEARNED that some things work, somethings dont. Do what u wish in what you do, but when someone has a opinion, listen to it, analyze it, prove it, then, shout it from the rooftops what u learned.
i think todays lesson is, where larry lives, av gas is better than your pump gas for peak power. it is a proven fact that gas is not the same everywhere. im sorry if our pumps carry the good stuff and DOES out do av gas on the dyno. now, ive taken the time to type this out, like i said, im not attacking you larry, but ur shoulder is awful, awful cold.

Anonymous-0 · Nov 16, 2012

cauldron on simmer.

Ole Johnny · Nov 16, 2012

I have run drag cars and drag boats for many years and I have used 106 and 110 and even 116, not to mention methanol, and i can tell ya that NONE of them work unless you TUNE YOUR CARBURETOR AND TIMING to run them. Such is the same with avgas. It is cleaner and it is 100 octain so you have less chance of detination from pump gas and when you adjust your carburetor to flow correctly it will run just as good as the 110 racing fuel. If you dont compensate for octain change you are shooting yourself in the foot and alll those that say that they "went and got some racing fuel and it ran like a scalded dog with nothing else done" were only running the engine too rich in first place.. I have used them all. And lest you think Im all blow, I have owned and have driven drag cars from stock to all out blown rear engine dragsters on alky ( 150mph in 1/8 mile at 4.5 seconds, that is just over 1400 hp friends). I learned from experience.

FactoryFarmer · Nov 16, 2012

Another benefit to AV gas is that it stores much better than regular gas does. It may be more expensive but it is worth it. It is actually manufactured to alot higher standards than regular gas because of what it's used for.

(quoted from post at 16:57:52 11/16/12) I have run drag cars and drag boats for many years and I have used 106 and 110 and even 116, not to mention methanol, a[b:d64c3eec38]nd i can tell ya that NONE of them work unless you TUNE YOUR CARBURETOR AND TIMING to run them.[/b:d64c3eec38] Such is the same with avgas. It is cleaner and it is 100 octain so you have less chance of detination from pump gas and when you adjust your carburetor to flow correctly it will run just as good as the 110 racing fuel. If you dont compensate for octain change you are shooting yourself in the foot and alll those that say that they "went and got some racing fuel and it ran like a scalded dog with nothing else done" were only running the engine too rich in first place.. I have used them all. And lest you think Im all blow, I have owned and have driven drag cars from stock to all out blown rear engine dragsters on alky ( 150mph in 1/8 mile at 4.5 seconds, that is just over 1400 hp friends). I learned from experience.

I could not agree more. In my G I run fuel that is 120+ research octane and it took me at least 10 hooks to tune the tractor to it's fullest potential.

I should also mention that AV gas is 110 octane, not 100.

Ole Johnny · Nov 17, 2012

It is great fuel but you need to supply more of it since it is aireated fuel. I used it in my drag car engines and it always GAINED me alittle power over inadequet pump fuel. But it is designed for airplanes that are up in thin air where the eingine needs more oxygen to run up there.On the ground, you dont need extra oxygen. Simply richen your carb and watch it burn the tires.
Tractor engine pistons dont know if they are in a John Deere or a Altered drag car. Richen the fuel supply to gain the advantage since it has oxygen in it and thus runs leaner.

loxjim · Nov 20, 2012

from what I remember from my navy school aviation machinest the best fuel in early years was 100 iso octane. then a mixture of normal heptane say 15% would be 85 octane. for the high compression engines, such as the 3400 h p 18 cyl 3350 required a better fuel than 100% iso octan so the new fuel was developed and given a performance no such as 110/115 + 115 145 if you dont have the compression you dont need ave gas. But ii was along time ago, so I'm just sayin

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