A little history about AvGas.
Back in the old days, there was three most common grades. 80/87(red), 100/130(green), and 115/145(purple). These were the most popular.
The first number indicated the octane of the fuel on a lean mixture and the second number was the octane on a rich mixture. (aircraft have manually controlled mixtures)
Well, back a few years (over twenty) the government stuck their nose in the tent and decided that there was too much lead in AvGas. Thus behold we now have 100LL(blue), the "LL" stands for low lead. Its was just given a single octane rating, unlike those in the past that had the dual octane rating. Fuel manufacturers took out some of the lead and added benzene(and some other stuff) because of its anti-knock qualities.
The only problem you may encounter running 100LL is hard starting in very cold temperatures. It will not rot out your rubber fuel lines like fuel that has alcohol mixed with it. It will not burn your valves either, like I have heard from so many misinformed people. It smells different when it burns and because it has lead in it, it will destroy your catalitic converter(if you have one). It is also illegal to run on the street because it is not taxed like automotive fuel.(like anyone would ever get caught by the tax man) It is illegal to be pumped directly into a car, so unless you have a friend that pumps fuel at the airport, you better bring a bunch of 5 gallon jerry cans to fill up.
The average comp ratio on aircraft engines is 8 to 1, and I have never seen an aircraft engine that has been damaged by detonation when running 100LL(even turbo motors that run 42" of manifold press at max power)
I have run 11 to 1 Pontiacs on AvGas and not heard a bit of detonation or seen any damage when the motor was torn down.
Wow, I haven't written that much since I got out of school [img]/infopop/emoticons/icon_smile.gif[/img]
Just my .02 cents
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"Run wild with an Indian, not with the crowd in a Chevy"
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Less said,,,,,,,, Less mended.
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