Does E85 make more power than gasoline in flexfuel vehicles?

[RDY4WAR]

Like you said the heat of combustion is higher when combusted in stoichiometric ratio (true), but then you stated it was in BTU/lb which (like you showed in your second post) is lower than gasoline, not higher (20k for gas vs 12.5k for ethanol). You were right that when combined at stoichiometric ratio there is more heat released -- but then it's not in units of BTU/lb. It's just in BTUs. (You could have said there is higher heat of combustion of the "charge air mass" which is how they would describe the proper combination of fuel and air in a textbook.)

I think you're misunderstanding my unit of measure. (or I'm still not tracking) I stated "BTU/lb of stoich air" as in "BTU per 1 pound of stoich air." For stoichiometric air/fuel ratio with gasoline, 1 pound of air calls for 0.068 pounds of fuel. 20,012 x 0.068 = 1,361 BTU per 1 pound of stoichiometric air which makes it easy to calculate the BTU released if you know how much unit mass of air is consumed in a 4-stroke cycle. Whatever the size of the engine, that formula applies. If a 307ci (5.0L) engine is operating at 100% volumetric efficiency, in sea level air at 15°C, it is consuming .0136 lbs of air every 2 rpm which commands 0.00925 lbs of gasoline producing 185.1 BTU per complete 4-stroke cycle. This is how I calculate fuel tables when setting a base line tune.

 

[bdc101]

I think you're misunderstanding my unit of measure. (or I'm still not tracking) I stated "BTU/lb of stoich air" as in "BTU per 1 pound of stoich air." For stoichiometric air/fuel ratio with gasoline, 1 pound of air calls for 0.068 pounds of fuel. 20,012 x 0.068 = 1,361 BTU per 1 pound of stoichiometric air which makes it easy to calculate the BTU released if you know how much unit mass of air is consumed in a 4-stroke cycle. Whatever the size of the engine, that formula applies. If a 307ci (5.0L) engine is operating at 100% volumetric efficiency, in sea level air at 15°C, it is consuming .0136 lbs of air every 2 rpm which commands 0.00925 lbs of gasoline producing 185.1 BTU per complete 4-stroke cycle. This is how I calculate fuel tables when setting a base line tune.

Yeah, I see what you are saying! I think we just come from different industries and use different terms to talk about the same thing.

 

[M104]

Thanks everyone, still learning things about E85. Always wondered how much more "displacement" comes from the oxygen when running E85. Filled my tank with E85 again an low end performance feels normal again. Ethanol content on this tank is about 69%.