ORIGINAL: vbortone
Bterry,
Please read this web page for the very simple and interesting conclusion:
http://www.smokemup.com/tech/fuels.php
One number is BTU/lb and I agree gasoline has higher number. However, the IC engine can convert to power a fraction of those BTU because of the oxygen already available in the fuel. Check the chemical formulas of each fuel. Gasoline does not have any oxygen. It is practically impossible to provide all the oxygen by aspirating air into the engine and this explain why gasoline has the lowest BTU rate production (power) when used in IC engine.
Vicente ''Vince'' Bortone
I did read that webpage and yes it is a very simple conclusion.
Modern pump gasoline is not in fact strictly Octane (C8H18), but is actually a mixture of hydrocarbons between C4H10 and C12H26 or so, plus other additives. Ethanol (C2H5OH) is present at a 10% in most of the US.
Oxygenated fuels (added hydrocarbon molecules containing an oxygen, typically an alcohol like ethanol) are more important in automobiles where we are held to running leaner settings for emission purposes, and the oxygenated fuels raise the octane rating a bit to allow running leaner without detonating.
The vast majority of oxygen available for use in combustion is from the atmosphere, and not from the molecule itself. The oxygen molecule available on the methanol is a very slight contributor to the combustion process itself. On top of that in a gasoline engine there is significantly more (2.5 times more) available air in the combustion chamber per stroke than with a methanol engine.
All that said, much work remains to be accomplished before gasoline is truly a viable power source for pattern. Your results on the Abbra prove that!
I still believe it can happen with a larger displacement engine, but the problem is those get so HEAVY it isn't worth the effort. A Moki 2.10 would be a good candidate due to its beefy crank and conn rod but it starts out at 42 oz or so, quite a bit more than even a 1.70dz.