Why does an e85 tune offer more power?

[Tromatic]

Originally Posted by GotBRZ1691

@Malt Great answer! Ive been doing research on E85 because I will be making the switch soon. Just to add a few things that I've seen or heard other users say. With the fuel economy, some have said they get 3-4 mpgs less per gallon while some have reported almost no change. In Cali, E85 is about a dollar cheaper per gallon, so even at 5mpgs less it would be worth the switch.

I'd love to get 5 mpg less. 18 mpg is the best I've done on E85.

[GotBRZ1691]

Originally Posted by Tromatic

I'd love to get 5 mpg less. 18 mpg is the best I've done on E85.

you were only getting 23 mpg per gallon with gas!!!! damn son thats a lot of

I drive highway at like 75 ish and drive in San Fran which is crazy hillie and im averaging 28mpgs. Ive had it up to 33 mpgs but thats no fun.

[DeliciousTuning]

Originally Posted by wparsons

Unless people with well sorted 94 octane setups are hiding, the dyno plots don't seem to support that.

There's lots of people making well over 200whp on stock headers and intakes with e85, but I haven't seen anyone with 94 octane and full bolt ons matching the power.

Sure it isn't a 30whp+ gap, but it's still a gap.

Yeah we have been able to hit 200+ whp on a completely stock vehicle on E85. But we have been right around 200 whp on 91 octane (+/- depending on dyno and temperature of the day). We have not really had a chance to tune for 94 octane being in California and wonderful 91 octane, LOL. Maybe we will see if we can get a mix and see what we can do as I am pretty confident it is totally possible to hit nearly the same numbers as E85 would on a completely stock setup.

We will work on that next as we have a batch of parts coming for our NA car to try out. JDL equal length headers, AirAid Intake, etc...

Cheers,
William Knose
Delicious Tuning

[nihontim]

This thread answered every question I had regarding this fuel variant. Thanks to all for sharing the information.

[scmil95eg]

Originally Posted by Mars2

Ethanol specific energy at stoichiometric fuel air mixtures is actually higher than gasoline allowing a higher release of energy per lb of air burned than gasoline.

Typical gasoline Thermal energy 19,000 BTU/lb max power fuel air mixture 12.5:1
Typical E85 Thermal energy 13,475 BTU/lb max power fuel air mixture 6.975:1
Typical ethanol Thermal energy 12,500 BTU/lb 6.429:1

If you are consuming 100 lbs of air, lets see how much fuel energy you release for each of these fuels using gasoline as the base 100% reference.
100/12.5 = 8 lbs of gasoline @ 19,000 BTU/lb = 152,000 BTU = 100%
100/6.975 = 14.337 lbs of E85 @ 13,475 BTU/lb = 193,189.9 BTU = 127% more heat energy
100/6.429 = 15.555 lbs of Ethanol @ 12,500 BTU/lb = 194431.5 BTU = 128.9% more heat energy

Typical fuel energy contents:
gallon of gasoline = 125,000 Btu
1 gallon of ethanol = 84,400 Btu

Nice post. Always refreshing to see someone reference air by mass instead of volume (almost useless).

So if I ran Nitro:
100/1.7 = 58.8 lbs of Nitromethane @ 5,000 BTU/lb = 294,000 BTU = 193% more heat energy

Does anyone know how to calculate how much air the FA20 actually pumps? By weight or volume?

[Tromatic]

Originally Posted by GotBRZ1691

you were only getting 23 mpg per gallon with gas!!!! damn son thats a lot of

I drive highway at like 75 ish and drive in San Fran which is crazy hillie and im averaging 28mpgs. Ive had it up to 33 mpgs but thats no fun.

I have at AT as well. If I get 25 with gas I'm happy. I've mentioned it a few times at the dealer. I do almost zero highway driving, though. And with Ethanol, why bother unless you get some fun out of all those resources wasted to make E85?

[arghx7]

Originally Posted by scmil95eg

Nice post. Always refreshing to see someone reference air by mass instead of volume (almost useless).

So if I ran Nitro:
100/1.7 = 58.8 lbs of Nitromethane @ 5,000 BTU/lb = 294,000 BTU = 193% more heat energy

Does anyone know how to calculate how much air the FA20 actually pumps? By weight or volume?

btu/gallon or btu/lb are oddball imperial units that are very difficult to work with. the standard is the SI unit of megajoules (a measure of energy) per kilogram (a measure of mass), the lower heating value.

just look at your mass airflow reading in grams/sec, at least on a stock car with stock intake where it should be reasonably accurate. it's a lot easier to work with energy content in terms of mass and metric units than weird imperial units. If you know the airflow and the air/fuel ratio at your given ethanol blend then you can calculate the fuel flow in grams/sec. Then you can calculate the energy consumption in joules.