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There was the 100/130 Green, which is now replaced with a slightly more expensive 100LL. The 100 is the lean number and the 130 is the rich number for Supercharged and Turbo applications.
100LL Satisfies both numbers with 1/2 the lead of the old 100/130.
Rarely will you see the 115/145 Purple, and that would probably be at airfields that host races, and or air shows that have planes with that need. Only a few companies still make that( Warter Aviation is one) and VP also has "Air Race" and a 115/145. It is NOT widely available and usually special order for those applications.
Swift Fuels 94UL Av gas is getting to be more readily available(Only for Approved Low compression Engines), but 100LL is basically the only fuel you will find.
Swifts 102UL and some other brands 100UL have not been approved for use yet outside of testing. You can't buy it.
In fact, some refineries have even stopped testing this as there just isn't enough need at this time.
Also, the cost will be an additional 65-85 cents per gallon to blend a safe Unleaded fuel for Aviation.
100LL will be around for a long time still. It works, is safe, stable, and reliable.
As far as "Formulas", there really isn't.
100LL is so regulated that the major refineries have all the same fuels with the same results. There may be slight differences if you compare SDS sheets, but no 100LL is sold that has not been tested to meet spec for Florida or Colorado. As you could technically fly, refuel and fly back.
There are ASTM requirements for 100LL including min and maximums for all specs including lead content.
They can't just blend a fuel and sell it without it being approved for use.
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Most people are jetting for oxygenated fuel. Av Gas is not. So you may balance out as close to the same.
Also, if you compare a distillation curve and burn rate of a typical race fuel to 100LL, they are very similar.
100LL and say C12( probably the most popular race fuel), you run on the rich side as the fuel typically has a more controlled and longer burn, resulting in a longer time of push on the piston.
Also, the detonation resistance allows for a leaner setting. This is never set in stone as there are many variables.
Pick a setting, say 50/50 or whatever and jet for that, and as long as you are not pinging or seeing signs of detonation, then you are good. Pure 100LL will allow you to BUILD horsepower into anything, same as a race fuel.
For those that wondered, yes, the numbers are derived differently, but keep in mind, 100LL satisfies the old 100/130 higher lead fuel(Green).
What year did Phillips rebrand their fuels to Track Tek? 2000 or so?
Sunoco may be the last major refinery brand making race fuel for sale to the public. Lots of offshoot brands though.
I/We (Trick) originally blended on the west coast. We had hired an ex Union 76 fuel engineer, Dave West as our consultant. At that time Dave had started San Luis Auto Recycling, as well as he and his wife had the original San Luis Sourdough Bakery in Downtown San Luis Obispo. There was an engineer at Union 76, Tim Wusz (sp?) who I would take samples of fuels to as part of his job was to test products. He would then share the results with me. I got to watch him do some Octane testing.
Good to see you on the board as there has been years of mis-information over a multitude of posts on here and you obviously have the education and skill set to speak correctly on fuels.
say I much appreciate your input here. Very interesting and informative. Thanks!
I know what the answer will be.
100% all correct. Some old school names there.
There are very few drawbacks(if you can even call it that) to a low lead (around 2 grams per gallon) fuel. Especially a non ethanol fuel.
Or any leaded fuel really even when not needed. I have a 2 stroke that is built for 100% C12 minimum(or equivalent) and really needs C14. C12 is 4 grams per gallon and I think C14 is 6 grams. I know C16 is 6 grams because I have an SDS sheet and specs right here.
I can’t believe people are worried about running a 100 octane LL fuel designed to run in and be safe in ICE aircraft engines. It ain’t Jet A and it’s dramatically better (quality, purity) than whatever happens to be in the tank at the local stop and rob mini mart.
IMO, the VP Racing fuels aren’t an option. They may be great for performance but the VOC’s they offgas are known carcinogens and frankly stink and at over $20 per gallon…. No thank you.
So what are your thoughts on mixing 91 pump gas with AV gas? Say 60/40 ration - 60 being pump? This would be in a 4 stroke. Not 2 stroke.
Do you need to? If you aren't pinging or getting detonation, it is kind of a waste.
I don't really trust 91 Super, so I run 1 gallon per 4 of pump in most high performance type engines as a cushion. I will say, most stock bikes are fine with 91 pump and the OEMs build in a cushion. Save for the YZ 125 which doesn't detonate on Swifts 94UL which if you can find it is about the same price as 100LL.
Or just cut it down. I buy a drum at a time so I use it as needed.
One last note, 2 years ago when 91 pump gas went through the roof here, 1.79 or 1.89 to 4.99 in 6 months, there was a few months stretch where 100LL was cheaper because of less demand and no road taxes. So everything was getting pure stuff. Then prices caught up.
I just bought 40 gallons a week ago.
Well I used to buy 110 sunoco and mix is 30% - 50% with 91 pump. I did notice the difference. Thus the interest in Av gas. I've never run Av gas before. '
Pit Row
If you look at the above picture I posted, 100LL is about a 105 MON with a max ASTM allowable 2 grams per gallon of TEL. To compare, VP C12 has 4 grams at 108 MON.C16 has 6 grams.
For the price, there is basically NO better fuel that has the control, regulation, and constant fuel pulls for testing. There are only a few major refiners producing 100LL and each batch has to match certain requirements to be sold. Thus the consistancy.
That said, Gami's 100UL has just received FAA approval after meeting detonation testing and starting requirements.
As the same for Swifts 94UL(basically 100LL with no lead) certain manufacturers have also certified the fuel for certain engines that don't require TEL. This 100UL also covere the old 100/130 Spec.
There is another 102UL that has not gotten approval yet, and not many airports carry any UL. (About 650)
As usual, to have a similar performance in an UL fuel, the cost for 100UL is 60-85 cents per gallon more than 100LL if they even have it. Most airports don't have extra trucks, pumps, or tanks for another fuel but surely they will be phasing out TEL.
The majors have had a 100UL and even a 102UL for years but never pushed it as their was no real demand, no regulation for it, and believe it or not, even airplane folks aren't keen on a 60-85 cent per gallon price hike.
That said, people think the cheaper price of an ~ 105 MON Av gas is because it is not race gas needs to understand most race gas base is 100LL bought in bulk and there is no marketing budget.
The FBO's work out a deal with one of the majors and sell whatever brand they can get the best deal on. Basically, it is all the same and has to meet the exact same specs for minimums and maximums of everything.
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