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Av-gas 100 low lead????

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oehm

Member
Joined
Jan 3, 2003
Messages
349
I have a friend that runs the local rural airport here, and he can sell me Av-gas 100 low lead gas for about $2.00 a gallon. Is this an acceptable fuel for a TR? Has anybody used this before? Unleaded 100 octane racing gas costs about $4.75 per gallon here.
 
i've used it before with no problems. 22-24 psi of boost. i don't know about anyone else.
 
You can also make 100 octane unleaded by mixing xylene in with 93/94 pump gas. I did this just recently for about a $3 a gallon total ($23 for 5 gallons Xylene).

-Banning.
 
100 ll is actually 108 if using the automotive comparison, r+m/2

great stuff but it is leaded so get a max effort asap so the o2 sensor is out of the loop.

Its almost I dentical to c-114 race fuel with half the lead content. Its actually hard to tell the difference except that the av gas is cleaner.
 
The experience I have with Av-gas is from when I was an apprentice Mechanic at my city Airport. Avgas is formulated for high altitudes well above 5000ft and the low lead slogan means compared to other Av-gas not auto fuel. The amount of lead in av-gas(even low lead) is substansial. dont be fooled! when I had to clean the plugs out of an airplane motor the lead would be caked all around the insulator. I would use a scribe to scrape it loose(Av plugs are $25+ apiece) and would have literally enough lead sand to fill a good portion of a teaspoon. Av-gas burns differently at ground level than say at 10000ft where the air is thinner and things tend to freeze easily. Thats where it was designed to burn. If you have an expensive high $$ mill DO NOT use Av-gas you will regret it. This stuff also is VERY dry just like pure xylene you will have to add a top cylinder lubricant too. Just remeber Av-engines are built like tanks the feds(FAA) require them to be. a lycoming 6 cylinder is around 540cid only runs about 8-1 compression,and only makes around 200hp. They could run off car gas which is cheaper than Av-gas, but they cant its illegal and dangerous because car gas is formulated for cars and to burn at ground level not at 5000ft or above where it would suffer from freezing temps,thin air etc.. and lose its octane rating.

HTH

Frank
 
Originally posted by LikeMy6
The experience I have with Av-gas is from when I was an apprentice Mechanic at my city Airport. Avgas is formulated for high altitudes well above 5000ft and the low lead slogan means compared to other Av-gas not auto fuel. The amount of lead in av-gas(even low lead) is substansial. dont be fooled! when I had to clean the plugs out of an airplane motor the lead would be caked all around the insulator. I would use a scribe to scrape it loose(Av plugs are $25+ apiece) and would have literally enough lead sand to fill a good portion of a teaspoon. Av-gas burns differently at ground level than say at 10000ft where the air is thinner and things tend to freeze easily. Thats where it was designed to burn. If you have an expensive high $$ mill DO NOT use Av-gas you will regret it. This stuff also is VERY dry just like pure xylene you will have to add a top cylinder lubricant too. Just remeber Av-engines are built like tanks the feds(FAA) require them to be. a lycoming 6 cylinder is around 540cid only runs about 8-1 compression,and only makes around 200hp. They could run off car gas which is cheaper than Av-gas, but they cant its illegal and dangerous because car gas is formulated for cars and to burn at ground level not at 5000ft or above where it would suffer from freezing temps,thin air etc.. and lose its octane rating.

HTH

Frank

Um, thats completely wrong, for the most part.
So if the fuel is design to run at 5000 ft + would n t be a really bad time to have poor engine performance when your landing or taking off, the most critical time of flying....Your right about the freezing part.....thats one way its better then auto fuel, it has no water in it, the crap that freezes and kills your engine.....thats why most people do not use auto fuel ( although I have seen it done) The amount of lead is half of 114 race and 1/3 of 116 If memory serves. The burn rate is fast, I don t have the exact numberin my head, but I have run it to 11500 rpm(I did retard the timing) with no ill effects. 7200 rpm for years in a bbc, so it can handle the 5000 rpm limit most tr's run...
 
Low lead AVGAS has a LOT of lead in it. Use it only if you have ME and the oxygen sensor is out of the loop.

I have a neighbor who is a specialist in fuels....He tells me that the amount of lead in AVGAS is Waaaay more than the "low lead" label implies. :)
 
As 1320 stated...the most crucial times in a piston engined aircraft is when it takes off and when it lands.

Low Lead aviation is blended to work at sea level to high altitude. There are numerous threads on this board about the successful use of Av fuel and the lead does not compare to the higher octane racing fuels altho it is higher than the term "Low Lead" might imply.

VP suggests the use of their Air Race gas for very high boost situations..but it is yet another animal. :)

I suspect those using the Denso O2 would be able to use the Low Lead as it seems to be surving on race gas. Any leaded gas will tend to leave lead deposits behind, tho.
 
As a commercial pilot let me chime in on this topic. Unless if you like changing valves then I wouldent run 100LL consistantly. A few years ago the lead content was used to lubricate the valves. There are addatives in gasoline (for lubrication pupropses) that you buy from the pump that arent in 100LL. Avgas is fun to run once in a blue moon, save your pennies and get an SMC kit. I did. Avgas is meant for aircraft engines, it dosent belong in our engines. The avgas is also strained out of the wing tanks before every flight. If you get water in your little ol 231 ur gonna be blowing head gaskets or even worse.
 
If you want Real World experience... I've used AV gas from my local airport for more than 10 years.
At $2 per gallon I only use it when I race; and I run about 24 pounds of boost. It has fouled my O2 sensor, but no other bad side effects.
If there was a negative side to using AV gas I would have known by now.
 
XLR8ER

I'm tired of argueing about this topic. Don't be cheap buy an SMC kit if wanna run boost on the street. I wouldent put anything but VP's C-16 Race gas when I'm at the track.

By the way what kind of times are you running anyway?
 
1320.... Av engines dont make alot of HP they make tons of torque! they dont spin more than 4000rpm most only turn in the 2500-3000 range! most are N/A! with only 8:1 compression so tell me MR. realestate broker why would they need 100 octane anyways?? I too ran 100ll in my 69 BBC Camaro since I could get it free, and I will say this that $hit it caustic over a period of time it started to disolve my float bowl and metering plate gaskets. Its like running alcohol over time it will harden rubber lines and other soft parts or cause them to crack. Thats why aircaft fuel systems are what all else is judged by. Why do you think you always see something high quality being sold stated as Aircraft quaility or certified? The FAA will not let anything go into or on an aircraft that it doesnt approve of 1st! I never said that 100ll had more or less lead that c16 or any other race fuel but that it does have ALOT of lead period and that the "low lead" was compared to other leaded Av-fuels. This stuff has a totally different burn rate than c-16 or any competition fuel. I also would like to know what times XLR8ER is running and what hes done to his motor. You dont see any of the guys here with stage2 motors running Av-gas, which they would be if it was as good as some here say. But no they spend $5.00+ a gal. for race fuel! I wonder why:confused:

Frank
 
I don't care to argue about theories but I do have a lot of real world experience. I ran AV gas for a year straight back when regular gas was almost the same price.

It does foul 02 sensors after a couple tankfuls hence my Max Effort. The octane rating is not comparable to regular auto ratings. I could run 20psi on regular auto 100octane. On avgas I had the boost as high as 24psi on 24 degrees of timing with no knock. I had ignition problems past that point so I have no idea if it would go higher. The car felt a little slower on Av gas before raising boost and timing. Also, when pulling into the local cruise spot if there was a wind people could smell me coming before they saw me and they learned how to tell when I was in race mode. This is what I have personally experienced.
 
Aircraft engines have huge cylinders. For example an engine in a cessna 172 is a 5.9L 4 cylinder and only makes 180hp. The red line on this engine is 2700rpm. Might I also add that cylinder heads are removed individually every 100 hours of flight time. Just stay away from Avgas.
 
Re: XLR8ER

Originally posted by Wht87T
I'm tired of argueing about this topic.

I don't see this as an arguement, really. It is view points from different angles so you can consider all sides of the issue. I'm sure there are truths to all sides here and no one should be so stubborn on their opinion or experience that they can't consider other possiblities. This has been an interesting thread but it won't be if it turns into hard feelings. :(
 
Re: XLR8ER

Originally posted by Wht87T
I'm tired of argueing about this topic. Don't be cheap buy an SMC kit if wanna run boost on the street. I wouldent put anything but VP's C-16 Race gas when I'm at the track.

By the way what kind of times are you running anyway?

A bit full of ourself, eh? If you're tired, maybe take a nap. :rolleyes:
 
I'm not sure how my earlier statement that I have used AV gas for more than 10 years could appear to be argumentative... when my intention was to purely state a true fact. I use Premium gas on the street, and AV gas at the track.
If you don't want to use AV gas, that is perfectly fine by me.

I have a basic recipe GN with bluetops and Thrasher chip... running consistent 12.2s at 24 lbs of boot. Fast enough for now.
 
As I stated above, I ran av gas for a year, every single day to and from work and on the weekends. Besides the performance gain there was no difference in plug change intervals, no lead buildup anywhere. The turbine wheel looked normal. The heads had the normal carbon but no gross lead deposits. Maybe the extra abuse these motors take compared to aircraft motors helps prevent lead from "sticking" around. Mine was beat on pretty bad daily.
 
Its not my car, you could waste your money on a bottle of Jack D and put that in your tank I really dont care. Its a free country. I just dont like it when people ask for a professional opinion and then complain about it. :confused:
 
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