- Joined
- Oct 19, 2005
- Messages
- 18,978
Ah the taste of siphoned hi test ethyl lead. Have a lookie here for some scope
http://www.klemmvintage.com/gasolines.htm
About Aviation Fuels - Aviation gasoline (or "av gas") is blended specifically for use in small aircraft. It's also commonly used by many high performance two-stroke owners because of it's high stated octane rating (usually 100oct) and the relatively low price compared to racing fuel. But it’s importance to understand some details about Av-gas.
Avgas octane is rated on a different scale than gasoline's 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, aviation gasolines are blended with no heavy molecule end. This makes a gallon of avgas weigh measurably 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 significant horsepower issue. Running 100% Avgas in a vintage two-stroke is not a good idea because there is a measurable loss of power resulting from the absent “heavy molecule ends”
http://www.klemmvintage.com/gasolines.htm
About Aviation Fuels - Aviation gasoline (or "av gas") is blended specifically for use in small aircraft. It's also commonly used by many high performance two-stroke owners because of it's high stated octane rating (usually 100oct) and the relatively low price compared to racing fuel. But it’s importance to understand some details about Av-gas.
Avgas octane is rated on a different scale than gasoline's 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, aviation gasolines are blended with no heavy molecule end. This makes a gallon of avgas weigh measurably 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 significant horsepower issue. Running 100% Avgas in a vintage two-stroke is not a good idea because there is a measurable loss of power resulting from the absent “heavy molecule ends”
