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AVGAS VS. RACE GAS?


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#1 donkeypuncher

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Posted 28 September 2008 - 12:48 AM

I was just wonderin which is better to run???

#2 flyhighprerunner

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Posted 28 September 2008 - 02:43 AM

People are going to talk about this all the time, but from what i have read and done my fair part of research av-gas is ment to be burnt at 30k feet. The air is much thinner, where as race-gas is ment to be burnt at a fair altitude. Even though race-gas is more expensive, it over-all in the long run is better for your engine compared to av-gas. (taken from transworld motocross magazine)

#3 pabansheematt

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Posted 28 September 2008 - 09:04 AM

I was just wonderin which is better to run???

Race gas is probably better but much more expensive. Race gas is $9 per gallon up here. Av gas is $4.85. I just filled my camaro up Thursday with it. My 406 chevy motor has been running on it for 7 yrs with no problems. I've ran it in all my bikes from time to time with no problems.

LL 100 (av gas ) is 100 octain in the air, on the groung its 115 octain. ( thats acording to my boss. He runs the local airport. )

#4 Speedy2222

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Posted 28 September 2008 - 09:31 AM

People are going to talk about this all the time, but from what i have read and done my fair part of research av-gas is ment to be burnt at 30k feet. The air is much thinner, where as race-gas is ment to be burnt at a fair altitude. Even though race-gas is more expensive, it over-all in the long run is better for your engine compared to av-gas. (taken from transworld motocross magazine)



i never knew privately own planes with props fly so high.. i thought they stuck to <15k

#5 RZBansheeMan

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Posted 28 September 2008 - 10:28 AM

If I'm not mistaken, I think it's oxygenated for high altitudes, and is a slow burning fuel.

I've also read somewhere that it's "supposedly" not that great of a fuel to run for performance aplications, but I've always ran it and never have had a problem with it.

I've ran it in all my CR's that I used to have and I ran it in my old Banshee which was stock, mostly when I was at Silver Lake dunes.

I think with the low lead content that it actually helps keep the cylinders lubricated.

Mike


#6 2001Stroker

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Posted 10 February 2009 - 10:29 PM

Just seen this. Figured I'd dig it up from the grave. During my quest to find what octane you need for your compression, I ran into a few specs on AVGAS. I don't remember the exact numbers, but AVGAS is basically like taking farm gas, and putting additives in it to make it burn like 100 octane fuel. It actually is 80 octane, with a bunch of additives. It burns very dirty. Someone on here recently posted pics of their Banshee engine, after running AVGAS for like 30 hours, I think. Disgusting looking.

#7 Banshee-Predator_Owner

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Posted 11 February 2009 - 12:20 AM

AVGAS is high octane (burns slower and has higher flash point) oxygenated fuel(less oxygen in the air at high altitudes) wont mess with your jetting tho, has a HIGH lead content, the lead keeps your top end cooler and is good for your valves/cylinder(lead is like a lube) but if u run it strait all the time it builds on your plug, most avgas has a die in it to detect leaks (gas leaks in planes=bad) so if your carb overflow or petcock leaks it dies your stuff but helps find slow leaks, RACE GAS is cleaner burning than avgas and you can get it oxygenated and leaded also, but it cost alot more, look up VP race fuels, i myself would run race gas/93 pump gas(dont buy it from somewhere no body buys premium, youll get bad premium which is worst than good regular, buy from somewhere that alot boats fuel up at) mix to suit your compression, avgas is like 115 octane, 115+93=208 208/2=104, u could run that with 19cc domes(standard stroke), +banshees drink gas and avgas is cheaper, my .02

#8 FireHead

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Posted 11 February 2009 - 12:35 AM

AVGAS is high octane (burns slower and has higher flash point) oxygenated fuel(less oxygen in the air at high altitudes) wont mess with your jetting tho, has a HIGH lead content, the lead keeps your top end cooler and is good for your valves/cylinder(lead is like a lube) but if u run it strait all the time it builds on your plug, most avgas has a die in it to detect leaks (gas leaks in planes=bad) so if your carb overflow or petcock leaks it dies your stuff but helps find slow leaks, RACE GAS is cleaner burning than avgas and you can get it oxygenated and leaded also, but it cost alot more, look up VP race fuels, i myself would run race gas/93 pump gas(dont buy it from somewhere no body buys premium, youll get bad premium which is worst than good regular, buy from somewhere that alot boats fuel up at) mix to suit your compression, avgas is like 115 octane, 115+93=208 208/2=104, u could run that with 19cc domes(standard stroke), +banshees drink gas and avgas is cheaper, my .02

Ok............. that's all generally wrong.

What kind of AV gas are you talking about? What you said might be correct for a specific variant.

I will support a technical discussion on this topic if y'all do the following:

1.) Search this site on this topic and read what is here already.
2.) Make sure we stick with specific type of fuel or products as opposed to nebulous terms like AVGAS and Race Gas.
3.) Be aware that this topic gets technical very quickly and I will get up on my soap box.

With all that said, Race Fuel or alcohol makes the most technical sense in a Banshee. Certain AV fuel can be used successfully, but it almost never the best thing you can do. :geek:

#9 regalrocket

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Posted 11 February 2009 - 07:42 AM

As a 10 year aviation mechanic and FAA licensed inspector, I will try to give some facts as I know them.

1. 100LL has ALOT of lead, something on the order of 5 times what normal automotive leaded gasoline had back when it was at the pumps.

2, This lead WILL leave deposits on piston tops and exhaust components (which accounts for it being "dirty" fuel) Lead is a white looking substance when it is deposited, but with the addition of our two stroke oil staining it with carbon, it looks like heavy oil deposits.

3. It is VERY HIGH quality fuel. A petrol engineer that I know said it is much much better than normal pump gasoline. It has very high quality additives, that will not break down. Aviation gasoline can last many years with zero breakdown issues. Its high quality is the reason that it smells totally different, and does not stink like autofuel.

4. It has a lower vapor pressure for high altitude use (similar to winter autofuels). USELESS AIRPLANE FACTS : Piston powered aircraft can rarely go over 14,000 feet unless supercharged, and if they are supercharged, normally 25,000 feet is the absolute altitude that can be obtained. Most 100ll aircraft never get above 8,000 feet.

5. The fuel is slower burning than normal gasoline. This is a good property for slower turning aircraft engines that never go above 3,000 rpm (except for the newer rotax engines). Automotive race gas is also a slower burning fuel, hence the high octane ratings. Take it for what its worth.



My personal opinion is that I would run race gas in a banshee just because of the lead deposit issue. Many aircraft were originally designed for 80 octane avgas, but with that no longer in production, we have to use 100ll. It makes a big mess of the exhaust and piston domes, leaving deposits that are heavy. We sometimes mix normal auto fuel to achieve a higher compustion temprature to help burn these deposits off, or keep them from developing. Avgas would be a great fuel for a drag machine or something that doesn't get alot of miles on it. But for a trail machine, I will keep burning autofuel. I wish avgas was better, as it doesn't stink 1/4 as bad as autofuel, but there is alot of lead in that stuff. Thats my 2 cents.

Edited by regalrocket, 11 February 2009 - 07:43 AM.


#10 2001Stroker

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Posted 11 February 2009 - 08:19 AM

regalrocket,

That's some good info for all of us to know. Thanks for sharing your expertise on this, and clearing that up. :thumbsup:

#11 shanYE west

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Posted 11 February 2009 - 10:02 AM

Found this awhile ago last time it was asked...


http://www.osbornaut.../race2avgas.htm

#12 FireHead

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Posted 11 February 2009 - 10:56 AM

As a 10 year aviation mechanic and FAA licensed inspector, I will try to give some facts as I know them.

1. 100LL has ALOT of lead, something on the order of 5 times what normal automotive leaded gasoline had back when it was at the pumps.

2, This lead WILL leave deposits on piston tops and exhaust components (which accounts for it being "dirty" fuel) Lead is a white looking substance when it is deposited, but with the addition of our two stroke oil staining it with carbon, it looks like heavy oil deposits.

3. It is VERY HIGH quality fuel. A petrol engineer that I know said it is much much better than normal pump gasoline. It has very high quality additives, that will not break down. Aviation gasoline can last many years with zero breakdown issues. Its high quality is the reason that it smells totally different, and does not stink like autofuel.

4. It has a lower vapor pressure for high altitude use (similar to winter autofuels). USELESS AIRPLANE FACTS : Piston powered aircraft can rarely go over 14,000 feet unless supercharged, and if they are supercharged, normally 25,000 feet is the absolute altitude that can be obtained. Most 100ll aircraft never get above 8,000 feet.

5. The fuel is slower burning than normal gasoline. This is a good property for slower turning aircraft engines that never go above 3,000 rpm (except for the newer rotax engines). Automotive race gas is also a slower burning fuel, hence the high octane ratings. Take it for what its worth.



My personal opinion is that I would run race gas in a banshee just because of the lead deposit issue. Many aircraft were originally designed for 80 octane avgas, but with that no longer in production, we have to use 100ll. It makes a big mess of the exhaust and piston domes, leaving deposits that are heavy. We sometimes mix normal auto fuel to achieve a higher compustion temprature to help burn these deposits off, or keep them from developing. Avgas would be a great fuel for a drag machine or something that doesn't get alot of miles on it. But for a trail machine, I will keep burning autofuel. I wish avgas was better, as it doesn't stink 1/4 as bad as autofuel, but there is alot of lead in that stuff. Thats my 2 cents.


I tend to agree with all of that. :thumbsup:

#13 FireHead

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Posted 11 February 2009 - 10:58 AM

Found this awhile ago last time it was asked...


http://www.osbornaut.../race2avgas.htm

That is generally good info as well. :geek:

#14 BellicoseBanshee

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Posted 11 February 2009 - 12:30 PM

I much prefer a naphtha-kerosine based fuel for my banshee... :whistling:

Yes, that is a facetious statement...

#15 Nick_R_23

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Posted 11 February 2009 - 12:33 PM

Ill throw in my .02, take it for what its worth.

My 1986 ATC 250R has a milled head, and requires race gas. In Alaska you can imagine how far I have to go to get it and how much it costs on top of that, no way Im paying that much. I live like a mile across from the airport, and so I have as much 100LL at my disposal as I can buy. I decided to try using AVgas in the 250R, I mix it with Klotz SuperTechniplate at 25:1 and so far Ive been impressed and havent had any problems, Ive been using this for almost 2 years now, and have taken the machine on long trips (50+ miles at a time). Ive noticed better gas mileage and the engine burns cleaner. Smells awesome too.

-Nick