Thread: Runnning aviation gas in outboard motors

My source of non-ethanol gas has dried up--gone to ethanol gas--and I was wondering if you could run 130 octane aviation gas in older (1987) 9.9 hp outboards, or is the octane too high? The av gas doesn't contain ethanol.

isnt' that a bit expensive? If I understand octane correctly you'd need hotter plugs just to ignite it as higher octane means harder to spark. So hotter coil/plugs. Not sure on performance but I'd think it would run higher pressures as well. Not sure why I think that tho...

My un-educated guess would be that it's a bit to much power/punch of a fuel for engines not setup for it...someone with more experience might correct me as that's just a guess based on my limited knowlege of AVGas.

You are right on Pomoxis. Very few outboards are engineered to run on even 93 octane. You are just wasting your money doing so.

Drive over to Batesville. There are still 2 stores that sell gas that do not contain ethanol.

Originally Posted by MaggiesMaster

My source of non-ethanol gas has dried up--gone to ethanol gas--and I was wondering if you could run 130 octane aviation gas in older (1987) 9.9 hp outboards, or is the octane too high? The av gas doesn't contain ethanol.

Unless you all know something about Av gas I don't, their isn't much difference in the fuels. Av gas is refined drier(no moisture). Lot colder at 5k/ft, don't want freeze up. Not sure today, but 20yr ago their was two fuels 100octLL (low lead) and 87oct. The 87oct may have been discontinued as the old engines phased out, so the 100ll maybe all you can get. I would think the 100ll would run just fine. I have never heard 130oct. not in gen. av.

Aviation gas is kerosine isnt it? If thats what I think it is dont run it, sure to blow your motor, runs too hot.

No You Are Thanking Of Jet Fuel To Run Av Gas You Need A Lot Of Compression And Good Hot Fire. We Use To Run Av Gas Our Drag Car Some Times.

Originally Posted by jimmy swanson

No You Are Thanking Of Jet Fuel To Run Av Gas You Need A Lot Of Compression And Good Hot Fire. We Use To Run Av Gas Our Drag Car Some Times.

Jim I don't think so. Aircraft engines are not high comp. They are designed for endurance. 100oct LL (low lead) wouldn't need big comp. to operate. The smaller aircraft, c-150's,172's and 182's are now aproved to burn auto fuel. The only change was valve seats and guides.

Funny, but some jet fuel is actually not as good as other fuels.

Originally Posted by Crappie Reaper

Funny, but some jet fuel is actually not as good as other fuels.

Slipedcork has it right. Jet fuel is kerosene thats refined to higher standards. Mainly its drier.