WOW I own a flex fuel car didnt know it

[rick-l]

Originally Posted by TheMentat

Huh???

If you add 10% ethanol, and your car has to burn 10% more fuel, doesn't that suggest that the ethanol produces approximately ZERO energy?

Someone's calculations are off by alot...

Are you arguing how the sentence is worded? I would take 10% ethanol added to mean it was 10% ethanol 90% gas. For ten gallons you would have 1 gallon of ethanol and 9 gallons of gas.

If that is not the case how do you calculate this? With gas I get 25 MPG so 10 gallons of gas I can go 250 miles. With 10% ethanol it takes 11 gallons to go 250 miles (10% more fuel). The 25 mpg is now 22.7 or 10% less.

[red-beard]

BTU content of dry ethanol is aproximately 75% of that of Gasoline for the same volume. BUT, alcohol is also hygroscopic. So the BTU content can actually be quite a bit less, by the time it used. Regular Gasoline these days is supposed to be 90% gasoline, 10% Ethanol. It might actually be 85% gasoline, 10% ethanol, 5% water.

E85 can be far far worse. It is supposed to be 85% ethanol, 15% gasoline. It might be 30% water.

And the taxes are based on gallons, not BTU content. So, yep, you get double screwed.

Welcome to how our government screws things up.

[TheMentat]

Originally Posted by rick-l

Are you arguing how the sentence is worded? I would take 10% ethanol added to mean it was 10% ethanol 90% gas. For ten gallons you would have 1 gallon of ethanol and 9 gallons of gas.

If that is not the case how do you calculate this? With gas I get 25 MPG so 10 gallons of gas I can go 250 miles. With 10% ethanol it takes 11 gallons to go 250 miles (10% more fuel). The 25 mpg is now 22.7 or 10% less.

What I'm trying to say, is that, you would only get a 10% decrease in mileage if the ethanol in your example had zero BTU content...

using a 75% equivalence to gasoline, and assuming that BTU content is directly related to fuel efficiency, a 10% blend would only decrease mileage by 10% x 25% = 2.5%, yielding 24.375 MPG

That is alot less than the 10% claim from masrum, hence my confusion...

[onewhippedpuppy]

I knew someone whould chime in with a nice ME thermodynamics answer, thanks Red Beard! Thermodynamics..........*shudder*.