Av gas

[this guy]

A friend and I went up to the local airfield to see how much it would cost to get low lead 100, turns out we can get it in town for 4.49 or 3.60 about 20 miles away. I was currious if anyone had tried this in their trikes? I have worked on aircraft quite a bit so I know its really good stuff, but I'm not sure how it would perform in a bike. I figured it would be awesome in a 2 stroke seeing as the lead would act as another lubricant. I may be wrong but wouldn't that mean I should run the mix a little leaner? Thought it would help my 4 croaker trikes too with extending the life of the valves perhaps? Anyway I am hoping you guys can help me out with this.

[4cfed]

i know there are a few guys on blaster forum that have been running av fuel for years.. of course there running ported stroker motors with advance timing, and i have yet to hear of any down side of running it.

friend of mine run 110 race fuel and klotz in his built 250r

[Dammit!]

I've been running AV gas in my R for years. Love the stuff.

[ChrisD]

I ran my R on low lead for years too. Don't waste your money on it unless you are running a high comression motor though. However, if you are looking for a cheaper alternative to race gas, it works great.

[Dammit!]

I can't run pump gas in my R and it's not a high compression motor. In the desert pump gas is ok but in the dunes it's under a heavier load and it detonates pretty bad with it. AV gas cured that problem completely.

The pump gas in Arizona is terrible quality though.

[sirceo26]

If your detonating doesn't that mean your not jetted right. You got to go a little richer I think so it doesn't run as hot.

[this guy]

Thanks all, I'm going to do it then, The tecate is pinging like my old zilla and Cr 250 did when they had pump gas in them.

[Dammit!]

If your detonating doesn't that mean your not jetted right. You got to go a little richer I think so it doesn't run as hot.

Detonation is caused by too low of an octane.

[Danold]

You are right in a sense that it acts as a lubricant in a 2-stroke, but in a 4-stroke its a little different. If you just ran AV gas in your 4 poke(which runs hotter than a 2-stroke) with the same jetting, you just might burn your valves up.

This is because even though AV Gas is 100LL(Low Lead) it still has a higher concentration of lead in it than normal pump gas. What happens is all the lead isnt totally burned and builds up on exhaust valves and pistons causing hot spots. This happens because lead melts at a lower temperature than most metals. This can cause premature wear of internals and eventual failure. The only reason it works so well in 4-stroke airplane engines so well is that they have a mixture control in the cock pit and they have forced cooling from the prop.

But with a little leaner jetting(to more completely burn the lead off) and a higher compression I think it would work.

This is what I have learned at avition maintanence school. Keep in mind this is only theory that I was thaught in school for 4 and 6 cylinder supercharged engines.

[cr480r]

its not race gas... but its way better than pump gas if you need somethin in between.. its lighter than pump fuels so you you may need to richen your jettin some

[Maico]

I always stick with race fuels...Klotz or VP. AV gas is designed for high altitude and low rpm.

[JohnR.]

Detonation is caused by too low of an octane.

The octane isn't the cause of the detonation, its the cure for it. The cause is either too much compression, too much timing advance, or to a lesser extent too lean of a mixture for the available octane. The reason engines blow up when they're run too lean is that they detonate themselves to death. I ran AVGas for a few years in my R with a Wiseco and a cut head. Once I stepped up to a fully built motor with a ton of compression I had to use race gas. With the price of race gas going through the roof I've been thinking about putting the bigger dome in the head and trying some AVGas again.

John

[crackshot]

You are right in a sense that it acts as a lubricant in a 2-stroke, but in a 4-stroke its a little different. If you just ran AV gas in your 4 poke(which runs hotter than a 2-stroke) with the same jetting, you just might burn your valves up.

This is because even though AV Gas is 100LL(Low Lead) it still has a higher concentration of lead in it than normal pump gas. What happens is all the lead isnt totally burned and builds up on exhaust valves and pistons causing hot spots. This happens because lead melts at a lower temperature than most metals. This can cause premature wear of internals and eventual failure. The only reason it works so well in 4-stroke airplane engines so well is that they have a mixture control in the cock pit and they have forced cooling from the prop.

But with a little leaner jetting(to more completely burn the lead off) and a higher compression I think it would work.

This is what I have learned at avition maintanence school. Keep in mind this is only theory that I was thaught in school for 4 and 6 cylinder supercharged engines.

What runs hotter? It actually runs COOLER with higher octane fuels.

[cr480r]

it only runs hotter due to the leaner mixture with the same jetting and the slower burn rate of the fuel may need require a timing advancement for a complete burn. i have ran alot of av gas with good results. its good in the right application if its readily available.. its higher octane than pump fuel, and much more consistent... but its NOT a replacement for race gas for engines than NEED race gas...

[JohnR.]

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I couldn't have said it better myself.

John