AV Gas (aviation gasl)

Has anyone tried AV gas in they're outboards? 100Octane, leaded fuel. No E-10.

Supposed to be more " stable " than automotive fuel.--------------If your local airfield will sell it to you then you should give it a try.

racerone said:

Supposed to be more " stable " than automotive fuel.--------------If your local airfield will sell it to you then you should give it a try.

Click to expand...

I use it all the time in my race car, and my home equipment. It's very stable, in fact with the additives for high altitude running, i don't think it ever breaks down, plus it smells great.

The problem is that i bought a boat last week, it probably has e_10 gas in it now. I hate to spend the $$ on AV gas to be ruined by water polluted fuel that's in the tank.

My airfield will sell it to me in 5 gal cans, but my tank is 60 gallons, eeek that a lot of cans (12)..

I will try it, but I wanted to check here first to see if any Yammy techs have any thoughts. With high octane and a ton of lead it is the coolest running fuel (non oxygenated) you can get.

Thanks for the reply:

See ya,
Rob

I've done a ton of testing with it. With my engine on a dyno. Comparing it to 7 different formulas of VP race fuel, and 93 pump gas (oxygenated). It produces as much power with AV gas as it does with $40/gal race fuels. Not all of them of coarse. But enough to convince me not to buy the fancy stuff. Just pay the $8/gallon for AV.

Aircraft engines generally do not run above 3000 RPM-----------Not sure if aviation gas could be called " performance gas "--------The lead makes no difference on a 2 stroke.

racerone said:

Aircraft engines generally do not run above 3000 RPM-----------Not sure if aviation gas could be called " performance gas "--------The lead makes no difference on a 2 stroke.

Click to expand...

Call it what you want I've seen the data and spent the $$ on fancy fuels to compare. I'm sorry, but I meant to say "i was considering it for a Yammy VF250, 4-stroke.

Lead acts like a lubricant in gas, whether it matters with a 2 stroke i don't know. I use it all the time in my 3 chainsaws never a problem. I've seen marginal HP gain with the little 2 strokes. I do notice the lead accumulation on the pistons of my racing engine, with no ill effects. Compression is great and leak down 1-2% and it seems to clean the intake runners and valves.

Since this yamaha engine is DI, it won't help the intake valve gunk accumulation issue.

The question in my mind are all the other additives needed for high altitude aren't needed for a marine product, will they blow by the rings and contaminate the oil? In the racer, the oil is changed daily, so no worries.*

The other issue is the nature of marine engines running at 100% duty cycle. Like you said aircraft engines rarely rev more than 3000 rpm's. What effect will the octane and lead have


The reason I propose using it is for the stability. The HP gain is more than marginal (6-10%).
Right now I'm paying 5+/gal for marina fuel. It seems better than pump gas since it doesn't have ethanol. if I can run $8/gal AV gas and not have to worry about phase separation then it's worth it to me.

Thanks for the good points and chat about it. I was hoping there might be a technician on here that could definitively give me thumbs up or down.*

Most mechanics agree that the higher the compression ratio the more octane is needed to prevent detonation.

Anybody know compression ratio of a VF250?

Take care,
Rob

kimcrwbr1 said:

My question is what would be the advantage of spending twice the price for fuel for a slight increase in performance. Also what would be the long term effect burning leaded in a unleaded engine it seems to me you looking for trouble, definately investigate it further before you chance burning up your engine.

Click to expand...

Remember back in the day, before unleaded? Everyone ran this stuff I don't worry about burning the engine up. The higher the octane the slower/more complete burn with the added lead actually runs cooler.

AV gas is not going to give an engine a " performance boost " all by itself.-------There are many reasons one might use it in an outboard !!--------------Much is known from experience and much can be learned using " google " on the subject.--Please note-------I am NOT calling AV 100 a performance boosting gas !

racerone said:

AV gas is not going to give an engine a " performance boost " all by itself.-------There are many reasons one might use it in an outboard !!--------------Much is known from experience and much can be learned using " google " on the subject.--Please note-------I am NOT calling AV 100 a performance boosting gas !

Click to expand...

Okay good points.. Thanks

I'd ask around locally where they sell regular gas without ethanol... There are several places in my area that sell non-ethanol gas... It seems to cost just a little more than the "premium" at the pump with ethanol. You are correct, AV gas has no ethanol as AV gas has to endure high altitudes which is a low air pressure environment. The reason AV gas has no ethanol is alcohol has a lower boiling point that true gasoline. Many airplane fuel pumps like outboard fuel pumps are mounted at the engine so theu SUCK instead of PUSH if they were mounted in the fuel tank like a car. THe sucking further can reduce the pressure on the fuel and, if extreme can cause a vapor lock. As far as the octane goes... the higher the octane the slower the fuel burns. Some high performance engines are designed to harness more power from a slower burning fuel. In regular outboards... no realistic performance enhancement is had with ultra high octane.

deepsea21 said:

I'd ask around locally where they sell regular gas without ethanol... There are several places in my area that sell non-ethanol gas... It seems to cost just a little more than the "premium" at the pump with ethanol. You are correct, AV gas has no ethanol as AV gas has to endure high altitudes which is a low air pressure environment. The reason AV gas has no ethanol is alcohol has a lower boiling point that true gasoline. Many airplane fuel pumps like outboard fuel pumps are mounted at the engine so theu SUCK instead of PUSH if they were mounted in the fuel tank like a car. THe sucking further can reduce the pressure on the fuel and, if extreme can cause a vapor lock. As far as the octane goes... the higher the octane the slower the fuel burns. Some high performance engines are designed to harness more power from a slower burning fuel. In regular outboards... no realistic performance enhancement is had with ultra high octane.

Click to expand...

Yea you probably would need to re-flash the ecu to get any real HP gains.

If your timing wasn't pre programed you could bump up the timing with the higher octane and probably pickup more HP. Remember the good old days?

Yeah.. the good old days. These days... I watch people pump high octane into their cars and pay a premium for it when it does absolutely nothing for them. Got to love marketing and the ignorant folk who buy into it. I'd say 99% of the cars on the road are designed to run on the regular octane and yet they keep selling the mid and premium grades like you read about. What a scam. Everyoen should check their owner's manual and read what octane is recommended and the engine was DESIGNED TO BURN. Good Lord!