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Old 06-15-2008, 02:27 PM   #12
hotrod
Scooby Specialist
 
Member#: 14141
Join Date: Jan 2002
Location: [email protected] @ 5800 ft on 13T
Vehicle:
2002 Impreza WRX

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First off it's still more money per mile to run e85. Also (for hotrod), there wouldn't even be this discussion of mpg's if there wasn't an issue with e85 being less efficient at making power, 25/30%. That's why you have to run such massive injectors. Once again the only thing e85 is good for is a high octane rating. 100+ octane. Remember octane is not power.

Regular Mid Premium Diesel E85 **E85 MPG/BTU adjusted price
Current Avg. $4.077 $4.329 $4.484 $4.797 $3.560 $4.685

**The BTU-adjusted price of E-85 is the nationwide average price of E-85 adjusted to reflect the lower energy content as expressed in British Thermal Units - and hence miles per gallon - available in a gallon of E-85 as compared to the same volume of conventional gasoline. The BTU-adjusted price calculated by OPIS and AAA is not an actual retail average price paid by consumers. It is calculated and displayed as part of AAA's Fuel Gauge Report because according to the Energy Information Administration E-85 delivers approximately 25 percent fewer BTUs by volume than conventional gasoline. Because "flexible fuel" vehicles can operate on conventional fuel and E-85,the BTU-adjusted price of E-85 is essential to understanding the cost implications of each fuel choice for consumers.
Did you not read my above post or simply incapable of understanding it?

My current fuel cost for E85 is $2.99/gallon, I get about 19 mpg in daily driving on it right now. That means it costs me 15.7 cents a mile to use E85. If I used pump premium, it would cost me $4.15 a gallon and I would get 22 mpg on gasoline. That means it would cost me 18.86 cents a mile.

Gasoline costs me 20% more per mile than E85!

As you mentioned that BTU adjusted price is a computed value that has nothing at all to do with E85's true cost to the consumer or its efficiency, it is a derived number based on false assumptions.

The major false assumption is in this statement:
Quote:
The BTU-adjusted price of E-85 is the nationwide average price of E-85 adjusted to reflect the lower energy content as expressed in British Thermal Units - and hence miles per gallon - available in a gallon of E-85 as compared to the same volume of conventional gasoline.
The fuel mileage per gallon available from a fuel is not tightly tied to its energy content per gallon. It is false to assume so, and since this is widely known in the community, it is clearly an attempt to misinform the public with false information. Fuel mileage is much more closely tied to engine efficiency and how well it makes constructive use of the available energy in the fuel. Since E85 has several characteristics that make it a more efficient fuel than gasoline you get more useful work out of a given amount of available fuel energy using E85 than you can on gasoline. In optimized engines fuel ethanol can achieve thermal efficiencies of 42% compared to about 30% which it typical of a well designed gasoline engine you see on the streets today.

Again another of your statements clearly show you have no clue about this issue.
Quote:
there wouldn't even be this discussion of mpg's if there wasn't an issue with e85 being less efficient at making power, 25/30%.
E85 and fuel ethanol actually have higher specific energy than gasoline, and can produce significantly more power for a given amount of air taken into the engine. In proper fuel air mixtures E85 is capable of increasing an engines power output from 5% to about 27% over what it could produce on pump gas with no other mechanical changes. You are confusing available energy content per unit volume of fuel with total power produced by the engine. That again is another false assumption! Total available power from a fuel is determined by how much fuel you can burn with a given amount of intake air. In the case of E85 at WOT max power fuel air mixtures E85 blows gasoline away completely. Likewise at light throttle cruise, you can run E85 at much leaner mixtures without misfire due to its wider flammability limits, and still have normal torque for passing and accelerating up hills because the fuel allows the engine to accept load at lighter throttle settings than you can get away with on gasoline. Net result is the driver needs less throttle and less fuel to cruise at a given highway speed, and he spends less time at higher throttle settings to pass or pull hills, resulting in significantly better fuel mileage than the raw BTU content of the fuel would lead you to believe.


You might want to look at real world E85 prices in comparison to regular gasoline and you will see in many areas of the country the price spread is large enough that E85 users are saving hundreds of dollars a year on fuel.

http://www.e85prices.com/

Larry
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Last edited by hotrod; 06-15-2008 at 08:32 PM.
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