The point that you are missing on this question has to do with the efficiency map of the engine. The auto makers do a resonably good job of getting the cruising speed of the vehicle lined up with the max efficiency region of the engine. When you change the fuel energy by 3.5% (E10 fuel), in many vehicles you move off the max efficiency region of the engine, and the result is a greater than 3.5% reduction in fuel mileage. This is particularly likely if the engine is somewhat underpowered to begin with. 10% reductions in fuel economy are very plausible w/ E10 v. 'real' gas, although my experience is around 5% is more typical.

In my experience, this can be predicted to some degree - if your vehicle is one that shows significant changes in fuel mileage when there is a headwind or a tailwind, then changing to E10 is likely to change mileage significantly. Conversely, if the headwind or tailwind doesn't change the fuel mileage, then changing to E10 likely won't change mileage significantly either.

Hope that helps clarify why.

 

There are a lot of factors that go into how and where an engine reaches max efficiency, but again, this is independent of fuel used (assuming it's the proper type, i.e. fuel for spark ignited engines. Sure it'll change drastically if one were to try to run diesel in an SIE). Fuel mileage difference definitely depends on the tune and adjustability built into the computer by the manufacturer. The engine still gets the same percentage of work out from the energy it's fed (fuel).

There's no question that for the same power output, it will take slightly more fuel when any amount of ethanol is introduced, which is where the steady-state highway fuel economy will certainly drop. I don't think that a set percentage decrease can be stated that would be true for all vehicles and engines.

 

I am wondering what the numbers would be comparing E85 VS 87 octane fuel.

 

Considering that we can't run 87 due to 12:1 compression and then boosting on top of that, I couldn't say.

 

Don't want to hijack thread but what would you say the optimal compression ratio would be to run E85 for max efficiency?

 

It probably depends more on the engine than anything else, but I'd say at least 10 or 11:1 on a average size V8. The engine we run is a 600cc motorcycle engine with 4 valves/cylinder, so it's pretty hard to compare that to much else.

 

Thanks, I was referring to my 99 Ranger with the 2.5L twin plug four. I have a custom Diablo two tune chip with one tune for E85. I am thinking of having the head plained to raise the compression ratio.
Dan

 

E85 has a 105 octane rating ((r+m)/2) and burns cools the intake charge much more than gasoline, so both of those are things to use as factors in determining an improved compression ratio. Keep in mind that what is optimal for E85 will be way too high for pump gasoline.

 

Thanks, I was thinking around 11:1

 

i don't wanna depend on foreigners for my fuel and give my money to them. i'd rather keep it in this country my using ethanol. i don't use it for the mpg or the cheaper price. simply because its the american thing to do

 

Thank You for supporting the American Farmer.

 

no problem buddy. concidering i've grown up around in one of the biggest corn producing states in the united states i should be supporting my neighbors and friends rather than the middle east

 

Why not support legislation to build more refineries and support more domestic oil? There would be a lot more people with jobs, unemployment would go down more. You would reduce the importation of oil. Our tax dollars wouldn't be subsidizing $0.51 a gallon for ethanol. We wouldn't have to worry about water problems and killing the soil to produce the amount of ethanol that would make an impact. (Currently, ethanol production compensates LESS than 1% of our oil consumption). No, 10% ethanol doesn't mean 10% less imported oil. Petroleum is used for a whole lot more than gasoline in your car. Drilling for oil is better environmentally than using all the land for corn and trying to keep the soil alive and irrigated. Why not support alternative fuels that don't cause environmental issues? Plus, the majority of the money going into ethanol doesn't even go to the "Farmers". It goes to corporations such as Archer Daniels Midland.

Sorry, but saying that buying ethanol helps support the American Farmer is like saying that it is going to end the war in the Middle East. Macro-Economics and Politics doesn't work that way. later... Mike....

 

I don't know what oil company you work for, but give it up..

Some of us like the idea of keeping the enviroment cleaner, and yes the oil mongruls have taken over the ethanol industry too. But I can brew my own if I wish, the permits to make fuel are available if I choose to obtain them.

My Ranger's oil stays cleaner now and the entire fuel system is cleaner. Power is better and my cost to run is same or lower.
Done

 

99F150; If you've read my posts in the past, you would see that I am very much in favor of improving the environment. Whenever and wherever possible. But, your rational of using ethanol is because you "like the idea of keeping the enviroment cleaner" is unfounded. Matter of fact, there are just as many conflicting reports that points out that ethanol may actually cause more and different health problems that fossil fuels do.

I am totally in favor of alternative forms of energy. i would like to see clean electric for everything. The point is, ethanol is not the answer. It isn't even close. We don't have enough land to make enough ethanol to replace oil. We don't have the water to grow enough crops for ethanol. Even though there are some exhausts that are better with ethanol, there are reports that ethanol creates other exhausts when are equally or more harmful. Ethanol ISN'T cheaper. Not when tax dollars subsidies $0.51 a gallon of ethanol.

No, don't go all emotional here and think that people who don't like ethanol are "Un-American", "Anti-environmental", or other negative attribute. The truth is; ethanol/gasahol has been pushed one way or another for more than 30 years. It's been pushed for political reasons. Henry Ford started with his cars on grain alcohol just like ethanol. Over time, it was realized how inefficient it is to produce compared to what you get out of it and petroleum was realized to be more efficient. None of that has changed in all these years. The Pro-Ethanol crowd and government have you believing that ethanol is a great thing. It's not.

My point is; there is more than enough oil in the USA to satisfy our needs for many years to come. We already know what it is and isn't capable of and it's side affects. More people in the USA have jobs, circulate income, are off welfare, etc... producing and refining a barrel of oil than there are making the same amount of ethanol. Oil/gasoline is cheaper than ethanol. And our environment/land doesn't get screwed up trying to over plant corn, beets, switch, cane, etc... to produce oil. It's not like we have all that much land. Especially considering how much of the USA can't grow anything.

And I never said that the Oil Mongruls have taken over the ethanol business. Unless you think Archer Daniels Midland is an oil mongrul.

But in defense of pure ethanol. IF our vehicles ran ONLY on ethanol; non of this flex fuel inefficient crap. IF somehow we could produce ethanol that didn't have to use up all of our land for growing the crops. IF we could control the by-products and environment/health risks. And if we didn't need to use tax dollars to subsidize the production of ethanol. Then I would consider it a viable solution. E85 in a flex fuel car is not as efficient as a PURE gasoline or a PURE ethanol car. No, because of inefficieny, you might believe then that it's similar to having E60 in an efficient vehicle. Therefore, 60% ethanol is reducing our dependancy on foreighn oil and helping the farmers. That's fine, you can believe that. But until the IF's can be taken care of, especially the health and environmental questions, I'd rather not use it. Later... Mike....