Ya, but Matt you went from Avgas 100LL mixed 50/50 with pump gas to comparing that to the MS109 right?
I dont think that is a very good comparison. But obviously you could feel the difference in power.
I would like to do a back to back test using MS109 vs. the Sunoco 110 or VP105 I can get from the pump a couple miles away. For some people Avgas may be the only alternative to some higher octane fuel. A 50/50 mix with pump and Avgas is better than blowing up a motor, thats for sure.
About Avgas and PWC from GroupK:
"Aviation gasoline (or "av gas") is blended specifically for use in small aircraft. It's also commonly used by many high performance engine owners because of it's high stated octane rating (usually 100-110) and the relatively low price compared to racing fuel. Unfortunately this fuel is not all it appears to be. Av gas octane is rated on a different scale than gasolines intended for ground level use. What is 100 octane "av", is not necessarily 100 octane "ground level". Besides this, there is also a big chemical difference. Normal ground level race fuels are made up of gas molecules that have a "light end" and a "heavy end". The light end of the molecule ignites easily and burns quickly with a low temperature flame (as a piece of thin newspaper would burn). The heavy end of the molecule is not so easily ignited, but it burns with a much more intense heat (as an oak log would). This heavy end of the gasoline molecule is responsible for the hotter, more powerful part of the combustion process.
Small aircraft are constructed as very weight conscious vehicles. That's because their somewhat weak engines often have difficulty taking off with any extra weight. To help reduce this weight problem, av gasolines are blended with no heavy molecule end. This makes a gallon of av gas weigh substantially less than a gallon of ground level fuel. Since small plane engines turn very low rpms and produce so little power, the omission of the heavy end is not a horsepower issue. However, for high output pwc racing engines, there is defiantly a compromise in power. This, despite the fact that many pwc owners experience the desirable cooler operating temperatures that "av" gas offers. In addition, some blends of av gas will quickly separate from some oils used in premix situations. For the above reasons, we do not recommend the ongoing use of 100% av gas, and we will not prepare any "av gas" engine kits. Despite all this bad news, running av gas (accepting the slight power loss) is usually a better choice than
burning down a high output engine on regular pump gas. In this situation, the best choice is usually a 50/50 mix of pump and av gas. That provides "some" heavy molecule ends for the engine. "
