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100LL AV Gas

fastfrontier17

Donation Time
Hi guys,

This doesn't necessarily pertain to modified only, but I figured since it was about 100 octane aviation fuel I'd have better luck here where octane level might matter more.

With my 2 smoke dirt bikes I typically run 93 octane in the winters, but in the hot summers I use 100 octane low lead AV gas from a nearby civilian airport. I can feel a slight difference in throttle response, but overall the lack of detonation is worth it. My question is, has anyone ever used 100LL in their beams and how did it perform when compared to premium pump?
 

husky drvr

Platinum Level Sponsor
Hi guys,

This doesn't necessarily pertain to modified only, but I figured since it was about 100 octane aviation fuel.

With my 2 smoke dirt bikes I typically run 93 octane in the winters, but in the hot summers I use 100 octane low lead AV gas from a nearby civilian airport. I can feel a slight difference in throttle response, but overall the lack of detonation is worth it. My question is, has anyone ever used 100LL in their beams and how did it perform when compared to premium pump?

FF17,

The only member that posted much about using avgas, that I recall was Nickodell. He stopped using avgas somewhat before he sold his Alpine. IIRC, it was because of the price.

Nick stopped posting after he sold his car, but he did check in on occasion. Sadly, it seems he hasn't even checked in for three and a half years.

If you search on "avgas" by member Nickodell, you should find links to several threads. Be forewarned, there is probably not a lot of real data, but a lot of opinions, about gasoline and octane in those discussions.

Hope this helps,
 

Series6

Past President
Gold Level Sponsor
I had a 1954 BMW motorcycle 600 cc and 9:1 with a sidecar with a lever on the handlebar to retard timing. For years I added additive. Long story but I ended up buying 3 gallons of 109 leaded racing gas to 2 gallons of unleaded 87/88 octane and ran great. No pinging, good plugs. Ran cooler.
 

puff4

Platinum Level Sponsor
Nick stopped posting after he sold his car, but he did check in on occasion. Sadly, it seems he hasn't even checked in for three and a half years.

Yeah, we haven't seen Nick on here for a great while. He lives about 1/2 hour away from me, in Phoenixville, PA. I am guessing, but I suspect he's near 85 years old by now.
 

alpine_64

Donation Time
I used to run 110 avgas in my alpine as i had high compression. It ran great, could advance the timing and never got knock... Downside... It goes through avgas faster than petrol and the price and access became prohibitive.

The advantage of avgas is also the lead content which helps protect the valves and no ethanol
 

puff4

Platinum Level Sponsor
I can understand why it would be advantageous to use AvGas... but keep in mind, it's a federal crime as well as a state crime (tax evasion). Just sayin'. :)
 

alpine_64

Donation Time
I can understand why it would be advantageous to use AvGas... but keep in mind, it's a federal crime as well as a state crime (tax evasion). Just sayin'. :)

Hadnt thought about the road tax revenue the state would miss out on.... Kimda makes me want to use it more ;-p
 

puff4

Platinum Level Sponsor
Kevin, what’s the statute of limitations on race gas?
No issues with race gas… if it’s used on a track. But as soon as you use it on public roads, if it’s not been taxed when sold it’s considered tax evasion.
 

fastfrontier17

Donation Time
No issues with race gas… if it’s used on a track. But as soon as you use it on public roads, if it’s not been taxed when sold it’s considered tax evasion.
I do believe AV gas is taxed here in GA. Super expensive compared to premium.

Has anyone tried E85, or are the downsides of ethanol just not worth it? IIRC e85 is 102 octane, but requires 30% more volume compared to gasoline.
 

puff4

Platinum Level Sponsor
It may be taxed, but not with road taxes.... and that's the issue. It's considered avoidance of road taxes.
 

fastfrontier17

Donation Time
It may be taxed, but not with road taxes.... and that's the issue. It's considered avoidance of road taxes.
Well then, I guess all the people using locally obtained vegetable oil or bio-diesel in their cars/trucks are right there with the bootleggers :D
 
Last edited:

Hodee

Donation Time
I have used AV gas in my Alpine. It runs very well but nothing extremely noticeable. My reasons for using it are the lead content and longtime storage qualities. And, it it near my house and jut a wee bit more expensive than premium but not much. I also have access to Ethanol free from the pumps so I often mix the two at a variety of proportions. Runs well on all ratios.
 

fastfrontier17

Donation Time
I have used AV gas in my Alpine. It runs very well but nothing extremely noticeable. My reasons for using it are the lead content and longtime storage qualities. And, it it near my house and jut a wee bit more expensive than premium but not much. I also have access to Ethanol free from the pumps so I often mix the two at a variety of proportions. Runs well on all ratios.
The only problem I had with 100LL was finding an airport which let you drive on the taxiway to get it. For me, that was about an hour away, and it was still sketchy. As far as ethanol free, the only thing I've found near me is 87 octane, which may work well with a 100LL mix, but in itself I wouldn't trust it.
 

fireroad

Donation Time
I’ve been running 100LL in my stock SV 5 for 10 years now and no issues. I did have to advance the timing slightly to get the full benefit. The one time I was forced to run pump gas with ethanol it ate through the carb seals and both had to be rebuilt. The nice things about 100LL is it has a 15 year shelf life so if the car sits for a spell you done have to worry about it going bad.
 

Pete S.

Bronze Level Sponsor
It may be taxed, but not with road taxes.... and that's the issue. It's considered avoidance of road taxes.

Just curious; How could anyone determine what gasoline you have in your tank and whether or not you paid road tax on it? Even if they could, how could they possibly prosecute you?
 

alpine_64

Donation Time
Just curious; How could anyone determine what gasoline you have in your tank and whether or not you paid road tax on it? Even if they could, how could they possibly prosecute you?
It's not that they are looking for you usign avgas.. They dont apply road tax to it.. So if you are buying it .. You are avoiding tax...
As for how they would know.... Very easy... The exhaust smells very distinct on av gas...
And if they bothered to take a sample.. Dont need a lab... The 100 and 110 avgas are coloured...so dont look like punp gas
 

Barry

Diamond Level Sponsor
How could anyone determine what gasoline you have in your tank ...

There is a standard lab test (D-5059) for detecting the presence of tetra-ethyl lead in gasoline.


Just curious; How could anyone determine ... whether or not you paid road tax on it?

There is no way in the U.S. to pay road tax on leaded 100LL aviation gasoline.


... how could they possibly prosecute you?

By charging you with illegally using leaded and / or non-taxed fuel in a road vehicle. Not likely, but certainly possible.
 
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