AV gas

[dritrider14]

im wondering if anybody would be able to tell me if running av gas in my truck is a bad idea ?

[CountryChevy15]

AV as in aviation fuel?

[dritrider14]

yep..keep in mid that i have no cats and o2 sensors

[CountryChevy15]

:thud:

[dritrider14]

thing is that my truck runs great ...ive been running it off and on for past 4 months ....runs great...my unle blew his boat motor up yesterday...we are thinking it cuz of the fuel...cracked his piston

[CountryChevy15]

So he blew up a boat motor and yet you want to run it in your truck?

[dritrider14]

ivew been running it for like 6 months...its free

[ragmc]

I used to run it im my toyota all the time

http://i103.photobucket.com/albums/m126/ragmc/OLD/img009.jpg

[Sellncars]

I ran it years ago in a Pro Street Trans Am with no problems.

[kemble]

Its actually loaded with additives to keep it from freezing. Its also a little higher octane. So in theory your free gas is robbing you of horsepower and more than likely causing deposits in your engine.

[shortstep4x4]

please explain how AV gas can be robbing him of power? Not being a smart ass, just curious. From what I've read on the subject most Av gas is close to regular leaded gas found in the 70's and currently at some gas stations that sell race gas. Octane rating seems to range from 80/87 to 100LL (low lead). I fail to see how that can cause issue if he doesn't have cats and O2's. AS for the additives I found little that I actually understood. Most require a degree in chemical engineering but for the most part a fuel stabilizer that reduced knock is the biggest additive.

Split piston on his uncles boat could have been any number of issues. From manufacture defect to detonation. Without more info it would be assumptions to blame the fuel. If he was running AV gas I would have a hard time believing the fuel did it. I would believe he thought it was a higher octane then the fuel really was and adjusted timing too much and didn't pay attention to the knock

[RichLockyer]

Higher octane gas than the engine requires is simply a waste.
Octane is not a measure of power... it is a measure of resistance to preignition/detonation.

However, I do not follow those who believe that higher octane burns slower or is "harder" to ignite. When the spark plug goes, it doesn't matter if it's 80 or 120 octane, it IS going to ignite, and the flame front speed is very close.

Lead and additives are the issuse... primarily lead.
There's a reason we can go 30/60/100/120k on a set of spark plugs, and that's because lead has been removed from gas. Modern valves and seats no longer require it for lubrication.... there is no advantage to having it in the fuel, and it does cause deposits in the cylinders and will require more frequent plug changes.
Of course, the tradeoff is that leaded fuels do not use MTBE or Ethanol as oxygenators or octane boosters. That's a very good thing.

If I had a cherry 1969 motor that did not need a rebuild, I would probably use leaded fuel to preserve the valves, but that's the only reason for lead in a modern engine.

Other than keeping an eye on the plugs and maybe changing them at 15-20k, I don't see any real issues using AVGas if it's free.
Would I pay for it? Hell no.

[shortstep4x4]

Higher octane gas than the engine requires is simply a waste.
Octane is not a measure of power... it is a measure of resistance to preignition/detonation.

However, I do not follow those who believe that higher octane burns slower or is "harder" to ignite. When the spark plug goes, it doesn't matter if it's 80 or 120 octane, it IS going to ignite, and the flame front speed is very close.


I think the misconception is from the belief that octane reduces knock because it's harder to ignite. The only reason I know of to use leaded fuel is like you mentioned, an older original car that needs it or because running alcohol is out of the question. Leaded race gas is used because some people don't or can't run alcohol for whatever their reason.

If it was free and I was running without cats and O2's I would use it as well but I use a wideband to monitor my AFR's so leaded fuel is out of the question. I'll run alcohol before I run leaded fuel.

[matt167]

higher octane for higher compression, running it on a low compression engine is a waste. no adverse effects, but a waste.. Lead kills cat's and O2 sensors, but there not a factor in this case

[shortstep4x4]

higher octane for higher compression, running it on a low compression engine is a waste.

Not entirely true. I have 8.5:1 compression and anything less then 91/100 mix causes knock. Yes I could dial timing back but then what's the point in having a turbo track car if you aren't on the edge?

Simply put compression alone isn't enough to demand higher octane but when you put boost or nitrous into the cylinder then you need a little more help controling preignition/detonation.

[Quyonmob]

100LL didn't burn the piston in the boat, likely a lean mix did.

Very commonly run in outboard motors at fly-in only fishing camps in Ontario and Quebec, simply to have one load of fuel for everything, and has a decent shelf life.

I ran some in my old TBI, only because I had it. It works, but isn't the right fuel for your truck.

[Brody57]

im wondering if anybody would be able to tell me if running av gas in my truck is a bad idea ?

Heres my thing, You've been running it for 6 months already and your JUST now asking if it will be harmful to your engine? lol

[6.0vortecchevy]

I say run it. If it blows the money you saved on gas will get a you a new motor. And if it don't keep running it

[RichLockyer]

Not entirely true. I have 8.5:1 compression and anything less then 91/100 mix causes knock. Yes I could dial timing back but then what's the point in having a turbo track car if you aren't on the edge?

Simply put compression alone isn't enough to demand higher octane but when you put boost or nitrous into the cylinder then you need a little more help controling preignition/detonation.
Compression (and a lean mixture) are the issues on a normally-aspirated engine.
Technically, it's not compression, but cylinder pressure that causes the problem, so yes... your turbo car will need premium, but generally, anything below 9.5:1 and often 10:1 can live on 87 if the mixture isn't lean.