AvGas 100LL

Blackfoot · Blackfoot's Garage

It happens that there is a small airport 2 miles from my house, and it also happens that I met the owner of the airport at Arby's and have lunch with him & his friends once a week.

The fuel the planes use is BP AvGas 100LL, a low-lead, 100 octane gasoline. So I got to thinking, the cat is a restriction and I was going to remove it anyways, so I could use the AvGas. But is there anything else I should consider before I put it in the tank?

$2.73/gal.

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-too many cars

todd951 · 10-02-2003, 06:27 PM

You say it is "low lead"? If it has any lead in it at all, it will screw up your O2 sensor.

Blackfoot · Blackfoot's Garage

ahhh, didn't think of that. any way around it, to have no O2 sensor i mean?

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-too many cars

Ebs · 10-03-2003, 07:43 AM

I have an '86 Euro spec model, which I believe started life without a cat (do you know if there is any way I can tell for sure?). The car now has a straight through 2 inch stainless steel system with only a small muffler.

I have run 100 octane Shell racing fuel in my 951. THis is identical to Avgas. Unless you are going racing, I don't believe you can really feel or see the difference in a 951 (and here in Australia our ordinary fuel is absolute crap). Whereas my dad has a 1962 122s Volvo and a 1979 Chev Camaro 350 and says he can feel the difference in both of those cars with Avgas. Unfortunately we can no longer buy Avgas.

robm-951 · 10-03-2003, 08:13 AM

I don't know if it's true or not, but I have heard that the lead will mess with the injectors (i.e stick to the needle, cause leaking injectors....). I have also read that av gas has a different density (lower?) and if this is true you would need to deliver more volume to make up for the difference.

Rob

IceShark · 10-04-2003, 12:46 PM

Don't use AvGas. Besides the lead inssue, LL or not, there is the mentioned density problem. More troublesome is the additives in AvGas.

Due to the lead content (even in 100LL form), a bromine compound is added to the mixture to scavenge lead residue from the engine. When the lead/bromine compound is burned there will be a small amount that remains in the engine. Lead bromide, when mixed with water, metals, and oil, will produce a corrosive liquid. That is why aviation oil is different from auto oil.

So, go ahead and use it but you better expect problems down the road.

Blackfoot · Blackfoot's Garage

IceShark, that's some interesting info, thx. i wonder if anyone has tried using aviation oil & avgas in their 951?

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-too many cars

IceShark · 03:23 PM

There are other reasons not to use AvGas. It will burn hotter than automotive gas which is not good, especially if you already tend to run lean - can you say burned valves and head gasket? It is formulated quite differently to make a gallon of gas lighter to save on weight so they cut out the heavier molecules. Additionally, the octane ratings for AvGas ment to be burned at altitude are not the same as the octane ratings for surface engine gas. In other words, for a car 100 race gas is far better for a car than 100LL, you WILL NOT be running anywhere near 100 octane if you burn 100LL in your car. Just don't do it, or I will kill you! was what a former girlfriend that was a Phd chemist for Amoco told me.

Manute · 10-09-2003, 04:07 AM

I really don´t know reasons not to use it,but i know there will be no benefits if you dont grow your compression or boost...the only benefit is to avoid detonation,but if the engine is more or less serial,you wouldn´t notice it.

Very cheap the avgas there! here doubles. How about regular?

Kirby2 · 10-31-2003, 02:37 PM

Call around for a Union 76 station selling racing gas, high octane, high price, no lead. It seems like a less complicated solution.

winddance@att.n · 12-05-2003, 02:56 PM

Avgas will destroy your car. There is 4 times as much lead in 100LL than in the leaded gasoline used in the 50's and 60's. Most older airplane owners refuse to use it in their aircraft, they use unleaded auto gas instead. If used, it is quite common for a Cessna or Piper, etc., to need a valve job every 200-400 hours! Read that as 10,000 to 20,000 miles in the car world. In fact, studies show there is enough lead in one tank of 100LL to lubricate the valves in an airplane, which is designed for leaded, for 10 tank fulls of unleaded gas! In the Cessna, Piper, Ercoupe, etc., forums there is thread after thread about this. So, 100LL isn't even good for the majority of private aircraft flying today. Why use it in your car?

Gordon Rankin · 12-06-2003, 11:08 PM

Union 76 is now being formulated with Ethanol , which I understand does not do well in our cars either. Factory does not recommend using ethanol in our cars.

Quote:

Originally posted by Kirby2
Call around for a Union 76 station selling racing gas, high octane, high price, no lead. It seems like a less complicated solution.

Manute · 12-07-2003, 08:29 AM

Quote:

Originally posted by winddance@att.n
Avgas will destroy your car. There is 4 times as much lead in 100LL than in the leaded gasoline used in the 50's and 60's. Most older airplane owners refuse to use it in their aircraft, they use unleaded auto gas instead. If used, it is quite common for a Cessna or Piper, etc., to need a valve job every 200-400 hours! Read that as 10,000 to 20,000 miles in the car world. In fact, studies show there is enough lead in one tank of 100LL to lubricate the valves in an airplane, which is designed for leaded, for 10 tank fulls of unleaded gas! In the Cessna, Piper, Ercoupe, etc., forums there is thread after thread about this. So, 100LL isn't even good for the majority of private aircraft flying today. Why use it in your car?

Here we all use avgas 100ll in the airplanes,no matter they are 30 year old pipers or cessnas,and the maintenance schedule is the same without problems.I think they use it here even with the older Boeing Stearman´s...

winddance@att.n · 12-07-2003, 05:26 PM

Manute: 1970's era is not an older aircraft. The majority of airplanes out there are 40 years old or older. An airplane ages 1 year for every 10 years a car ages. My 1956 cessna 172 is relatively 4 years old. The reason why you don't see maintenance problems when YOU ALL use 100ll is because you haven't compared it to auto gas. Check out the piper or cessna websites/forums and you will see why you should change. You will save yourselves 10's of thousands of dollars by getting the stc for auto fuel and using auto fuel. The concensus among almost every older aircraft owner out there is that the only reason people use 100ll instead of auto gas in their older planes is because the Gov decided to call it aviation gas - and mechanics are making a fortune off pilots who are unwilling to change. This is why the 80 will soon be coming to an airport near you. I have nevr heard or read of anyone having the same maintenance problems or repair history with auto gas as they do 100ll. My 0-300 Cessna 172 has been going 1100 hours without a top end job. You will never see an older plane that uses 100ll go even 1/2 that long. The hours for a top overhaul with 100ll use at my airport is usually between 200 and 400 hours. Check the cylinder temps for newer vs older planes. The older planes do not get hot enough to burn the lead out even if you follow strict leaning procedures. The newer planes burn hotter so they can burn the lead out.

Manute · 12-08-2003, 03:02 PM

Maybe you are right,but here are a few factors that made auto gas not an option.For example,the older planes here are no more than about 35-40 years old,and the actual engines are all modern,so a 35 yearl old piper mounts a,not more than 2 year old engine...That´s because it´s not common to overhaul them,when an engine reaches overhaul time,say at 2000 hours,then the engine is replaced with a new one.And it´s very common to see cherokee´s 140 with the newer 160 warrior´s engines.And this engine can afford the avgas 100LL....people did it´s schedule,with no problems.And think that,in modern engines,lycoming or continental voids most of the warranties if you use auto gas because,true or not,legally they don´t respond in most of the cases.At least,as far as I have read here.
And also,flight schools,the majority users,get discounts on avgas, making auto gas actualy more expensive.
Maybe the hot temperature here help,but for sure i didn´t saw overhauls on engines with 400 hours...something like that would make us think the engine is defective.
One thing is sure,maybe you are right,because private aviation here costs about triple than there...

Wolf1 · 12-08-2003, 09:47 PM

I used to run Avgas and Bel-Ray synthetic racing oil at a 50-1 mix ratio in my highly modified CR-500 dirt bike..

I never had any fuel related problems, of course it probably only ran 40-50 hours a year. But, they were all wide open drag sprints up the sand dune...

Ebs · 12-09-2003, 04:31 AM

Lead is deliberatly designed for one purpose - to lubricate valves. The only downside I can see is if you have a cat. Otherwise I would think it would be beneficial, which is what my mechanic also maintains. Cars of olders desigen, particularly with iron block and heads are suffering from valve recession when running at higher rpm or carrying heavy loads. A fact that is being widely acknowledged in Australia and UK where lead has been phased out of petrol and replaced by a poor substitute.