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100ll Avgas Ok to run?

creynolds

Well-Known Member
Wow....awesome info guys. keep it up. I might have to print this page so I can refer back to it easily!! There's always been so much confusion and conflicting info on this subject. It's nice hear some hard facts regarding the matter. I've always heard keep your fuel in a cool dark spot and in a sealed metal can. Why specifically a metal can? Is it because it will breathe less due to the integrity of the material? I'm sure a metal can will also probably seal better than anything plastic that's out there.
 

VeryFast

Well-Known Member
You should be able to get a way with Av Gas using your numbers of 11.5 to 1 compression with Aluminum Heads on a water cooled motor. No way with an air cooled motor.

Something we all experience in the desert that the road racers don't, ie. Nascar, Vintage races, etc is a change in Barometric pressure, elevation and the actual "load" on the motor from our larger tires and the soft terrains. All off-road engine builders who have been around for a while run there motors somewhat rich because of these three factors. It is better to be a little safe than sorry.
 

blacksi

New Member
Veryfast, I love your post, on this topic...I am not a desert racer, although I do have a fully built turbocharged car making 453HP and 337Tq to the wheels. My question is also about the AVGAS 100LL....The Avgas 100ll we get here in St. John's, NL, Canada, is a SHELL fuel, I recently found out that I have access to it and can use it if I wanted to or if I had my car retuned with an Avgas tune or something like that. I was on the SHELL website, I will post the link here for you to have a look at... SHELL's 100LL claims to have a higher octane....they say that how aviation fuels octane are described as lean mixture which they say is the same as the MON of Pump gas and Rich mixture which is the same as RON number of Pump gas....So they say that thier AVGAS LL100 has a lean mixture of 100 and a rich mixture of 130 so in using M+R/2 that gives a pump gas equivalent of 115octane. What do you think? This would be awesome for those of us here that like to race at the track on occasion and having 115oct available here would be fantastic...here's the link :

http://www.shell.com/home/content/aviation/aeroshell/technical_talk/techart12_30071515.html

Thanks for your time...
 

scottm

Well-Known Member
Yes veryfast's post was epic. I have referred people back to this thread many times over the last 4 years. And just a week ago someone was complaining about their boat q-jet carb, and I told them I haven't had the one on my rv apart in 15 years. He asked how is that possible - answer is I put 10 gal of avgas in it at the start of every summer, and drive it around the block to get it in the carb. Then it can sit for 3 months with no carb problems.
 

37minotti

New Member
Been using Avgas for years in BBC, just be sure to add 2 ounces of Marvel Mystery Oil for every 5 gallons of gas. I use it in all my yard equipment too, very consistent and has great shelf life.
 

dzrt performance

Well-Known Member
also remember you can be fined for using AV gas. The feds have mandated it for use in aircraft only so be careful where and how you get it.

and yes i have used in with great results.
 

redmist

Well-Known Member
AvGas has a regulated TEL content 3 times that of old (now banned) leaded gas. I ran it in my Jimco twin turbo until we pulled down one of the engines and noted a tonne of pilled lead in the exhaust ports.

This is why we switched to E33, which ran cooler for the same HP and Ethanol doesn't give me the same troublesome headaches when you wash your hands in it.
 

Big Whitey

Well-Known Member
Great answers. I ran av gas in my bikes for awhile and in a hayabusa powered race buggy and never had issues but was told by some it was not a good idea while others said it was a non issue. The answer that made the most sense to me was when I was told to run the engine on whatever octane it was built for
 

JDDurfey

Well-Known Member
You also run into the tax issue if you start to produce your own Biodiesel. I know of a few people that jumped on the garage brew band wagon 13 years ago when that was all the rage. In fact, I seriously considered it and did a ton of research about producing my own. I had a facility lined up to use and planned to go into producing it big time. But after carefully considering the whole thing, I round filed it.
 

Bert is my name

Well-Known Member
I've been a mechanic for almost 20 years and have an extensive background with performance tuning. A lot of the " street engines" I've built and tuned ran 25 to 50 percent low lead mixed with citgo premium and marvel. Detonation was rarely an issue even on hot days. Proper cam selection and big cooling systems also help.
 

MTPyle

Well-Known Member
I am a Pilot that flys a piston powered plane that uses 100LL, and I have been running forced induction race engines for years. I would not run 100LL in anything that is not set up for it. As others have said the density is different and will run lean. 100LL also has drying agents that dry out rings. 100LL will mess up the o2 sensors if you have them. It only takes a few tanks to clog them and create bad readings. So for any EFI I would stay away from 100LL. Also it is not 100 octane the same that race fuel is 100 octane, different measurement systems and I think 100LL is more like 97 or so octane.
 

VeryFast

Well-Known Member
Glad to hear many are getting usage out of this blog. I have continued racing but have been out of the blending, sales, transportation of race fuels for many years now. Answers to a couple of the previous statements I read:

100LL AV Gas has no drying agents. Most all airplanes have built in water seperators for condensation issues as these issues can happen while in flight.

100LL AV Gas has a motor octane rating MOR of 97. 100 is R+M method of octane rating.

100LL AV Gas has 4.2grams of Tetryl Ethyl Lead TEL. Approximately the same as most 110-112 octane race fuels.

Marvel Mystery oil is hydraulic oil... plain and simple. It does lubricate, but does NOT lubricate rings, cylinder walls, and valves. In fact, it makes the combustion chamber a ticking time bomb for detonation. The Hydraulic Oil forms got spots along the cylinder head causing pre ignition.

Race on....
 

jon coleman

Well-Known Member
i new that oil was good for somthing, my floor jack was leaking so i put in lucas ps stop leak, mystery oil, some eng oil , all left overs, hasent leaked since.
 

MTPyle

Well-Known Member
Glad to hear many are getting usage out of this blog. I have continued racing but have been out of the blending, sales, transportation of race fuels for many years now. Answers to a couple of the previous statements I read:

100LL AV Gas has no drying agents. Most all airplanes have built in water seperators for condensation issues as these issues can happen while in flight.

100LL AV Gas has a motor octane rating MOR of 97. 100 is R+M method of octane rating.

100LL AV Gas has 4.2grams of Tetryl Ethyl Lead TEL. Approximately the same as most 110-112 octane race fuels.

Marvel Mystery oil is hydraulic oil... plain and simple. It does lubricate, but does NOT lubricate rings, cylinder walls, and valves. In fact, it makes the combustion chamber a ticking time bomb for detonation. The Hydraulic Oil forms got spots along the cylinder head causing pre ignition.

Race on....

Veryfast

Aircraft that use AVgas 100LL do not have water separators. They have drains at the lowest point where water accumulates that you can drain.

I don’t know where the dying agents story comes from, been told it by many old school pilots. I need to do some research and find out if it’s an OWT.

I think AVgas is more stable at lower temps than pump gas. But again only repeating what I have heard.

Would be interesting to talk to a expert to find out what additives it has beyond TEL.

Mike
 

Josh 8

Well-Known Member
It’s been a long time since I studied avgas in a&p school. But here is want I remember. The 100 is actually a performance rating. Not a octane number. 100LL is actually about 107 octane.

Avgas lasts for a long time. It doesn’t go sour. It also weighs less per gallon than auto gas. This is where the problem comes in. If you have your engine jetted on the ragged edge like a drag racer with auto gas then switch to avgas it will be lean and burn pistons.

Reason is it has less gas density per gallon. That’s why a gallon weighs less. If you jet up a size and 107 octane works for you you will be fine. But your mpg will fall off some. Also, as stated above it does not mix with water. You need to be able to drain off from a sump to get the water out. Over time condensation with build up and cause a problem.

Also, even though it says low lead in the name (LL) it still has huge amounts of lead in it. That’s good for engines. But the epa doesn’t like it. And the feds don’t get there road tax if you burn it on the street.

And as mtpyle said. The lead does a number on an o2 sensor if you have one.

It’s good stuff. I buy lots of it each month. And it dries clean too. Great for cleaning stuff. It smells good too. Just don’t smoke or weld around it.
 
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