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Old 10-05-2011, 12:26 PM
herc herc is offline
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Join Date: Apr 2011
Location: Southeast WI
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Vehicle: 2011 Ram 1500 Quad Cab 4x4
Trim Level: Laramie
Color: Deep Water Blue
Engine: 2009-???? 345ci (5.7L) Hemi V8 390hp 407lb/ft
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Flex-fuel cars and trucks take roughly 1.4 gallons of E85 to go the same distance as they could go on 1 gallon of gas. The ethanol actually ADDS a little (tiny) bit of power, but the energy content (BTUs) is only 2/3 of what's in gas. So, you don't lose power (in theory), but you DO use more fuel.

Applying that same logic to 10% ethanol gas says that you'd HAVE to lose a little bit of MPG. If you need an extra .4 gallons when the ethanol percentage is 85, then you'd need an extra .05 gallons if you have 10% ethanol. So, if you get 16 on pure gas, in theory you'd get about 15.25 on 10% ethanol.

Our hemis aren't flex-fuel, and there's lots of variables involved, but for those that think they get better "performance" on pure gas, I wonder if it's real, or if it's because there's a little more pedal needed. Dyno tests I've seen (on FFVs) show no power loss with E85. As I said before, power actually goes UP, but by such a tiny amount that you wouldn't notice it. It'd be real interesting to see an actual dyno comparison on the hemi using pure gas vs. 10% ethanol.

Last edited by herc; 10-05-2011 at 12:29 PM.
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