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AvGas is short for Aviation Gasoline. AvGas is of interest to motoring enthusiasts because of its availability, octane rating and low price compared to commercial race fuels. AvGas might seem an obvious choice but closer study raises some doubt.
AvGas LL100 stands for "Low Lead 100 Octane". TEL (Tetra-ethyl-lead) is added to raise the octane. When used in a motor vehicle this fuel will leave a lot of lead deposits in the motor. 100LL has a high lead content (0.5 grams per litre), even higher than leaded race fuels. The deposits left when TEL(lead) is burned are corrosive and damaging to valves, valve guides, valve seats and cylinder heads. Lead deposits will also block oxygen(lambda) sensors and catalytic converters and foul spark plugs even after only a short use. Also, 100LL has a chemical package added to make it perform at high altitude, and that isn't the best thing for motor vehicle performance here on the ground.
AvGas is blended for large-bore, long-stroke, low RPM engines which run at high altitude. While AvGas' higher octane is useful, smaller-bore, shorter-stroke, high RPM engines will perform better on racing fuel or high quality octane boosters. AvGas has lower volatility so when used in proportions higher than about 40%, part-throttle drivability and cold starts may be compromised. AvGas has a lower specific gravity so it will require a change in air-fuel ratio calibration for the engine to perform at its best. LL100 is blended with a high percentage of aromatics causing reduced throttle response which is not an issue with an aircraft engine but certainly an issue in a high-performance automotive engine. These high levels of aromatics will also damage rubber components in automotive fuel systems such as fuel lines, fuel pump seals and injector washers.
It's $5 a gallon compared to whatever VP offers. Usually twice as much. VP is great, but I'm a weekend warrior, not an expert or pro. 100LL gets my money.
Oh, and don't put it in a 4 stroke. Only 2 strokes like 100LL.
Always puzzled me.
Probably started by race fuel companies.
That fuel is used extensively in small A/C, and most of those are flying around 3-4000 ft.
My guess is a fair amount of the members here ride at those altitudes.
For how much fuel you use racing is it really that significant of a difference in cost savings ???
I understand this post doesn’t really answer any of your questions lol
Pit Row
https://nasaspeed.news/tech/engine/octane-vs-horsepower-separating-fact…
Yesterday, I rode Twisted Development's '07 YZ 250 project that was based on a thrashed basket case that Jamie got from Austin Howell...it ran like a champ on the track and on amazing single track out behind Cahuilla...
It was running on VP's T2.
I've mixed it down to 60:1 (by using VPR) and have alway been impressed with the performance.
I've used it in everything from Husky TC125s and TE 150s to Jet Ski 550s.
I ran AV gas in my YZ465 and my 05 CR250. 40:1 with Maxima SuperM. Both bikes ran horribly on pump gas. It was night and day difference running avgas in my bikes. I tried 50/50 C12 and pump 91 but could not tell the difference except for paying $70 for 5 gallons of C12. Avgas is about $18 for 5 gallons.
I went on to comment on T2 working on other stock bikes and even my old-school Jet Skis.
Octanium is $20 a can and I mix it into 10 gallons. The best part is I can do it one gallon (or even less) at a time. It keeps well in the steel can it comes in. I tested it, initially, on a stock RMZ 450 w/ Yosh pipe: it made California pump gas much better and eliminated "pump pop" that the RMZ with a white-plug (map) can get.
At the end of the day though this would mainly be an issue at low elevations and when used on cold days. Seeing as dirt bikes arn't exactly a winter toy with some exceptions Avgas will do fine for most.
Paw Paw
I don't mind paying $25 for a jug of gas though. $50 just seems like a ridiculous amount on principal. And I'm a bit of a cheap bastard.
It's worked and continues to work for me so that's what I do. That's the science de Sir Wreckalot.
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