Quote:
Originally Posted by Easy Rider  Let's not lose site of the original claim.
Kindly explain to me what causes the decrease in mileage if it is NOT less energy (power) contained in the fuel. ????
This is not magic. The total energy IN must equal the total energy OUT.......and oxygen does not add to the total energy, it merely varies the rate at which it is produced.
A given unit volume of alcohol contains less energy than the same unit volume of gasoline. WITHOUT ANY CHANGES IN ENGINE OPERATING PARAMETERS, this results in less power and less mileage. |
I agree with most of what you said, but I believe that you are getting hung up on the less energy fuel = less energy output. It's not so much that ethanol has less energy than 87 octane gasoline but that the gasoline engine designed for 87 octane is not going to burn the 110+(?) octane rated E85 effectively.
The thing is, the gasoline engine is extremely inefficient and requires the correct conditions to produce maximum (albeit little) efficiency. In the engine, efficiency doesn't so much depend on which fuel has more energy capacity but whether it is burning when it should.
Higher octane fuels burn slower than lower octane fuels. If the fuel burns too fast, (I'm sure most of you know) you get knocking (explosions), which is bad for the engine, and its efficiency. To remedy knocking, you can either retard the timing, put in a higher octane fuel, or reduce the compression ratio (which reduces the possibility of the fuel exploding and also reduces the horsepower).
To get better engine horsepower (I was going to say efficiency, but now that I think of it, that might not be true), one of the things that can be done is to increase the compression ratio, which requires a higher octane fuel that is less likely to explode when compressed. So, to explain why the Ford FFV gets better horsepower with E85 is because the engine is tuned to work better (and I
assume more efficiently) on E85, but it can still run on 87 octane gas because it can automatically adjust timing, etc. to run on 87 without major engine damage.
Anyway, my point to Easy Rider was that the energy out (horsepower to the wheels) of a gasoline engine has less to do with the total energy available in the fuel than it does with how that energy is used. Putting acetone in your gas tank will increase your fuel efficiency and horsepower not because you put that much more energy in your tank but because it changes the burning characteristics of the fuel (i.e. aids in vaporization).
If you modified your motorcycle engine by adjusting compression, gear ratios, etc. (I know Easy Rider's comment was qualified with "WITHOUT ANY CHANGES IN ENGINE OPERATING PARAMETERS"), you with probably be able to get better horsepower and comparable gas mileage with E85. Of course, you'll get worse, if not damaging, performance from 87 octane, and your fuel lines, etc. will probably not last as long. Also, I think ethanol is more corrosive than gasoline.