The "E85" Ethanol Topic

[OUSux]

Here is what I'm averaging so far through half a tank. May be time to try 93 octane. Stock truck, stock everything fyi.

[block8head]

Do you feel the different in power?

[Silverado Steve]

It's no secret that ethanol doesn't produce efficient energy, hence the loss in mpgs. Did you expect otherwise?

[haider320]

You're always going to get more power with E85, but will suffer in mpg.

[RyanbabZ71]

Been getting around 9 mpg in my 2010. 4wd, remote start, E85 all add up to less fuel economy

[OUSux]

Do you feel the different in power?

 

 

No...should I? I do notice it switches and stays in V4 a lot more though vs. 87 I typically run

[OUSux]

It's no secret that ethanol doesn't produce efficient energy, hence the loss in mpgs. Did you expect otherwise?

 

 

Honestly I didnt know what to expect, first time running E85, just posting my findings, that is all.

[OUSux]

So next question is, will I notice anything different going to 93 octane?

[haider320]

So next question is, will I notice anything different going to 93 octane?

Better mpg..

[OUSux]

Better mpg..

Better than 87 octane results?

 

(opps I meant to hit quote but hit edit sorry removed my comment and reposting RB)

[MIZ14sierra]

Short chemisty lesson here: energy content of ethanol is much less than that of normal gasoline, regardless of octane rating; on the order of 40% less on a btu/lb basis and 34% less on a volume (btu/gal) basis. Octane does not equal energy, octane refers to a somewhat comlipcated rating system (R+M)/2 to evaluate how closely the molecules in the hydrocarbon product gasoline resemble and behave like the molecule iso-octane (2,2,4 trimethylpentane) when combusted. The goal posts for octane rating are n-heptane (zero octane rating), and iso-octane (100 octane). Molecules that are more highly branched like iso-octane (think more numbers in it's chemical formula generally) tend to reduce knock, which to my understanding is essential in high compression engines (think, turbo/supercharged, and apparently your new Ecotec3 engine).

 

Now for the soapbox part: while the octane rating of ethanol may be high (100), it's engery content is horrible and you are being robbed at the pump when your government forces you to buy 10% ethanol blend and still labeling it gasoline. Electing to buy E85 is basically just a donation to corn farmers at this point, because the huge reduction in btu/gal is not offset by the 10-15 cent price break.

 

Someone who is more gearhead inclined may be able to explain the mechanical reasons (advanced timing, compression, higher fuel/air mixture ratio, etc.) for the increased HP from E85 fuel in high compression engines, energy density of E85 vs pump gas explains the horrible mileage.

 

I am curious to run through a few tanks of 91-93 octane (not the ethanol supplamented octane boost stuff like they sell at Caseys) to see if there is an improvement in mpg and AFM staying in V4 mode. If the MPG boost is more than the 7% or so upcharge for premium gas it would prove to be worthwhile.

[RyanbabZ71]

Better than 87 octane results?

 

(opps I meant to hit quote but hit edit sorry removed my comment and reposting RB)

 

Possibly but your truck is designed for 87 or E85. A 93 octane tune would suit it best

[legierk]

Better than 87 octane results?

 

(opps I meant to hit quote but hit edit sorry removed my comment and reposting RB)

In my case, ALOT better. 87/89 ~17-17.8 mpg. 93 ~18.5-19 mpg. All stock (as of now).

[MikeNH]

E85 will get you more power but crap MPG numbers. For my driving it seems that 70 or 75 cents cheaper is about where E85 needs to be to be cost effective. I usually run it regardless because power>fuel economy but lately I've been doing 93 so I don't have to buy gas as often given how cold it is outside (truck is tuned so its 93 or E85).

[voltedge]

I have a station that carries ethanol free gasoline which has a octane rating of 90. It costs 60 cents per gallon more than regular unleaded as well. While buying my off-road diesel for my farm equipment yesterday, I decided since my truck was a little under half full, to top it off with this 100% gasoline. The truck feels more responsive than ever and powerful as well. I also noticed when I drive it conservatively and focus on keeping it in v4 mode that it has average 23.9mpg!!! This was only for 90 miles thus far, but what a difference!