Some good info on avgas vs. autogas

[F-16Guy]

I was reading some of the old threads about avgas, and everyone had different opinions on whether it was bad or good for a motor. I decided to do a little research, and I found this interesting article. Most interesting to me were the difference in octane ratings, and the pros and cons of the higher lead content of avgas. It dispells some of the myths about avgas, also. Enjoy!

http://www.eaa.org/education/fuel/autogas_vs_avgas.pdf

[JOEX]

I skimmed over the first page and there seems to be some good info here. I'll have to read the whole thing when i'm in a better frame of mind:p

Thanks for the link!, Joe

[MOFO]

I just skimmed it myself as well....saved for later reading. From what I gather 100LL would have an octane rating of around 105-107 if I am reading that right. Looks like I may have to hit my local airport up for some 100LL soon for the quad...

I used to work at an airport years ago and we would steal 100LL all the time for our vehicles. I used it for about 1 year before I got rid of that car....NO problems at all. The only side effect was the smell of AVGAS...much different from regular gas. Must be that bromine burning up as the article stated.

[F-16Guy]

The bromine seemed to be the only real drawback. It's tendancy to attract moisture, and therefor corrosion, is easily taken care of by changing the oil on a regular basis. This should be a given for anyone with a motor that would require avgas in the first place. The octane is rated strictly by the motor octane number, not an average of motor and research, as with auto gas. It's purity is second to none, and the small amount of lead will help cool and lubricate the engine. I can't find any faults for $2.50/gal.

[QuadJunkies]

I had a friend tell me it was ok to use so I made a thread on it and was told NOT to.( for a few reasons)Thanks for posting the link.good info there......;)

[F-16Guy]

That's exactly why I did some research. Everyone seems to think they're the expert, or they know a "friend of a friend" that said do or don't use it for whatever reason. I think this article dispells a lot of the myths about whether avgas burns hotter or colder, or is only for high or low rpm use. The actual defferences I found were that 1) avgas is manufactured under much tighter tolerances, 2) it contains a small amount of lead to raise the octane, and as a side effect, lubricates the top end, 3) it contains bromine to scavenge the remaining lead from the engine. Bromine attracts moisture, and can cause corrosion. This can be alleviated by frequent oil changes (which you should be doing anyway), 4) the octane of 100LL (low lead) is actual motor octane, the equivalent of about 108 auto gas, which is R/M2, 5) the vapor pressure remains constant, regardless of region or time of year, which will eliminate the possibility of vapor-lock. I don't see anything that would indicate a potential for engine damage. Light aircraft are typically four-stroke, internal combustion engines, just like a quad. I don't see how the fuel could be radically different in composition, aside from being of better quality and higher octane. I'll run some in my bike next weekend and tell you guys (and girls) what happens. :cool:

[twisted threads]

thats funny you brought this up. This weekend I was buy some race fuel and the guy that was pumping the fuel for me asked me,"why don't you buy Avgas??" I told him that I heard it was bad for your motor and I didn't want to mess my motor up. He said, No you will not mess up your motor, it will work fine.
SO.. I say if this guy is willing to lose $$ from me not buy race fuel from him than he must know what he is talking about. :cool:

[QuadJunkies]

[QUOTE]Originally posted by F-16Guy
That's exactly why I did some research. Everyone seems to think they're the expert, or they know a "friend of a friend" that said do or don't use it for whatever reason. I think this article dispells a lot of the myths about whether avgas burns hotter or colder, or is only for high or low rpm use. The actual defferences I found were that 1) avgas is manufactured under much tighter tolerances, 2) it contains a small amount of lead to raise the octane, and as a side effect, lubricates the top end, 3) it contains bromine to scavenge the remaining lead from the engine. Bromine attracts moisture, and can cause corrosion. This can be alleviated by frequent oil changes (which you should be doing anyway), 4) the octane of 100LL (low lead) is actual motor octane, the equivalent of about 108 auto gas, which is R/M2, 5) the vapor pressure remains constant, regardless of region or time of year, which will eliminate the possibility of vapor-lock. I don't see anything that would indicate a potential for engine damage. Light aircraft are typically four-stroke, internal combustion engines, just like a quad. I don't see how the fuel could be radically different in composition, aside from being of better quality and higher octane. I'll run some in my bike next weekend and tell you guys (and girls) what happens. :cool: [/QUOT So what would be the Gains out of running it???? But.....for a stock motor does it relly do anything for it? run cooler?I look forward to your review......

[powerslider]

That whole article only deals with the concerns of using auto gas in airplanes so it really doesn't answer anything about the reverse usage of avgas in land vehicles.

[seven]

Tina, Just try it. You wont notice huge gains unless you run a high compression motor. It will help on throttle responce and over all make the quad run a bit smoother. Also I would run a 50-50 mix with your normal gas. Just try it, Youll like it.

[RUNMYTA]

I have been running 100LL (AVGAS) in my ported Banshee with 215lbs compression for 2 years. Now I am currently running it on my 300R with 240lbs of compression. AVGAS (for Me) actually makes my bikes run smoother, have better throttle response, and stay slightly cooler. Occasionally I will have to run 110 from Conoco and when I do my bikes do not seem to run as well and I always foul a plug on the Shee.

You need to take in consideration that AVGAS has a higher oxygen content than "Race fuel" With using AVGAS you need to jet usually one size larger on the main and fine tune the air screw..... This is to compensate for the leaner condition from the extra oxygen.... THIS IS MY PERSONAL EXPERIENCES ON 2 STROKES:D

AS far as using AVGAS or Race Fuel on stock or lightly modded bikes: I think it is a waste of money. High octane fuel doesn't make horsepower or torque!!! Actually it will slow your bike down slightly. High octane fuel burns slower than pump fuel. This is why it is needed on high compression engines to fight detonation. Therefore no benefit to stock/lightly modded bikes.



:macho MIKE

[250rpilot]

thanks for posting that link F-16guy, great info!!

[seven]

I tried to tell Tina that but she never believes me:D

[QuadJunkies]

Originally posted by seven
I tried to tell Tina that but she never believes me:D :eek: is that so.......:p

[F-16Guy]

Originally posted by powerslider
That whole article only deals with the concerns of using auto gas in airplanes so it really doesn't answer anything about the reverse usage of avgas in land vehicles.
The fact that the two can be interchanged answers the question about one burning hotter or colder than the other, and the article clearly states that avgas is much purer and more consistant than auto gas. I went to the airport the day after I posted this thread (it was closed, so I couldn't get any), and 100LL avgas was only $2.35/gal!! That beats the crap out of $5/gal, and for essentially the same benefits. Jacking up the price of "race fuel" to $5/gal only works because people will pay for it. That won't fly (pardon the pun) for people filling up a Piper or a Cessna, so the price stays reasonable. Prices, be it on parts or fuel, only reflect what the market will bear. :cool:

[trx400]

this is a stupid question but are airports the only place to get avgas

[MOFO]

Originally posted by trx400
this is a stupid question but are airports the only place to get avgas


As far as I'm aware of, yes. Unless you know a fuel supplier that could get you some. Make sure the airport has some kind of FBO (fixed base operations)...thats where you want to go to get fuel. Next time I go to my parents house, I'm pickin me up 15 gallons or so...

When you get the fuel, make sure its 100LL... some places still sell the lower octane stuff...I think its called 80LL or something like that.

[400EXPILOT]

I would not use Avgas "100LL" in any of my toys. I have been fueling them and flying them for 12 years. We use to put avgas in our fuel trucks until the one quit running . We pulled the spark plugs out and all of them had Lead Deposits a 1/4 In. high on them plus the part that you gap was gone yes gone the only thing left was a sharp point . If you go to the tech articles and look for the spark plug color chart and find the deposits pic you will see what avgas will leave behind. Just my .02

[MOFO]

Originally posted by 400EXPILOT
I would not use Avgas "100LL" in any of my toys. I have been fueling them and flying them for 12 years. We use to put avgas in our fuel trucks until the one quit running . We pulled the spark plugs out and all of them had Lead Deposits a 1/4 In. high on them plus the part that you gap was gone yes gone the only thing left was a sharp point . If you go to the tech articles and look for the spark plug color chart and find the deposits pic you will see what avgas will leave behind. Just my .02


interesting. How long did it take for that one to show deposits like that. Also, fuel trucks are usually idling or slightly over idle during most of their life (while your pumping fuel). I wonder if this is the reason? I would imagine that a high reving single piston motor would keep it pretty clean...

[seven]

I have run av gas for about 8 years now under race conditions with no failure. The only issue is it will make your engine run a little leaner.

[400EXPILOT]

Yea the high revs would most likely keep the plug from forming deposits like that but man seeing it and just knowing it could.
No avgas for my 400!!!

[MOFO]

Originally posted by 400EXPILOT
Yea the high revs would most likely keep the plug from forming deposits like that but man seeing it and just knowing it could.
No avgas for my 400!!!


I know what you mean. I'm gonna run it, but I can tell you that I will be watching my plug conditions very closely. Hopefully I will be doing a 416/425 kit this winter, so I'll see what the inside looks like after a 1/2 season of runnin it.