The "E85" Ethanol Topic

[KARNUT]

Whats the self life on E85? I found one place in town that has it not sure many buy it here.

[fondupot]

Never run it in mine. But I'm curious about the power improvments...gotta try to find a station with E85 now and do a few tanks worth.

[KUUG]

The power gained isn't worth the drop in mpg to me.

It is cheaper but my mpg seems like it almost gets cut in half. For me it cost way more to run E85 and I'm not racing my truck so I don't really care about the hp.

[Shier32]

I tried searching, but didn't find any results. Anyone here know were the price point is where E85 is an advantage/disadvantage price wise?

[MIZ14sierra]

I posted on the chemistry of E85 previously:

 

http://www.gm-trucks.com/forums/topic/156625-e85-fuel-economy-in-the-toilet/?p=1392701

 

To be clear, unleaded can mean anywhere from 0-10% ethanol. I'm assuming you're not talking about ethanol free (E0), and you are talking about 87 octane E10 (most common/cheapest). On a btu/gal basis (what you pay at the pump), E85 has ~26% less energy content/gal than E10. At $3.30/gal for E10 87oct, this would require E85 to be $2.43/gal or less for break even. A data set of real world comparisons would be a better tool, but this estimate is based on chemistry.

[Silverado Steve]

It depends on what you're averaging MPGs wise. Here are my numbers.

 

Using regualr unleaded, I am averaging 15.3 mpgs. Using 24 gallons as a baseline fillup, that's 367.2 miles to the tank.

 

My last fillup was using E85 and I'm averigng 13 MPGs, so with 24 gallons that is 312 MPGs for a difference of 55 miles less on a tank of E85.

 

Those 55 miles divided by my average of E85 is 4.2 Gallons (55/13). So it would take an additional 4.2 Gallons of E85 to equal one tank of Unleaded using my averages.

 

Right now E85 is close to $1 cheaper a gallon ($2.64) than Unleaded at ($3.57) at the gas station I normally go to

 

So, 28.2 Gallons (24+4.2) at 2.64=$74.49 for Ethanol

24 Gallons at $3.57=$85.68 for Unleaded for the same miles per tank.

 

Even at the lowest price in the area for Unleaded:

$3.40x24 Gallons Unleaded=$81.60

 

E85 seems to be more stable in price, with gas fluctuating as of late. To keep from having to recalculate every time I fill up, The 20% rule seems to be close; therefore E85 needs to be about 20% cheaper than Unleaded to make it worth it. For my last fillup 20% of $3.57 comes out to .70 a gallon, which the price I pay locally far exceeds that.

 

I'm going to reassess after my next tank. Sorry for the long post, but I wanted to use real numbers.

 

 

[MikeNH]

I did some testing back in 2012 and figured 70-75 cents cheaper was the break even point for me too.

[MIZ14sierra]

Also, this:

http://www.fueleconomy.gov/feg/bymodel/2014_GMC_Sierra.shtml

 

Government seems to agree/admit to the ~26% mileage reduction. E85/Regular for 5.3L 4WD ---->> city 12/16= 75% hwy 16/22=72.7% combined 13/18=72.2%. average all of those because not enough significant figures (no decimals provided): 73.3% or a 26.7% reduction according to EPA. multiply your 87 octane price by 73% and that's what the E85 price must be below to break even. at $3.50 a gallon thats about 95cents

[Northside]

I just filled up with E 85. I'll see how the mileage works out. I see another possible long range benefit in that it should run cleaner, thus result in less contamination to the oil. If it generates less heat and contaminates the oil less it might prolong engine life. While the plugs last a long time now their life should improve too. It's supposed to raise my top horsepower by 25 to 380 and increase the torque too. That's got to be worth something. The biggest downside is that it isn't practical for long trips, at least in my part of the world.

[MIZ14sierra]

not sure what burns "cleaner" means. EtOH has no sulfur so no SOx emissions, burns cooler so less NOx, but increases many other tailpipe emissions like formaldehyde, acetaldehyde and methane.

http://www.afdc.energy.gov/pdfs/technical_paper_feb09.pdf

 

There is detergent/additive added to petroleum fuels at the pump, multiple O2 sensors, engine knock detection, etc. now that incomplete combustion and coking doesn't seem that much of a concern relating to spark plugs and engine gumming. If GM engineers were worried about burning cooler, they wouldn't have designed a DI 11:1 compression ratio engine i would imagine either. The HP bump is apparently from the way EtOH burns throughout the entire piston stroke, rather than just at the top of the stroke. If you need the HP increase, go for it, it just comes at a sacrifice. The downsides of EtOH are the added cost to make your vehicle capable to handle corrosive alcohol, EtOH affinity for water, especially in a large vapor space (empty gas tank), and energy dilution. thats before you get down the rabbit hole of how inefficient the whole process is. If you role in the tax subsidies to the cost of ethanol/gal it would be totally obvious its not economical, or ecological.

[iCryWheniGoPoop]

All true, any actual gains outside of performance are minimal if any. By the time you figure in the fuel consumption rate for E85 vs Gas, the carbon foot print will be the same, maybe even worse. I hate trees anyway, always screaming at me and pointing and laughing. Almost made me stop doing acid once.

[kstruckcountry]

Also takes ~700 gal of water to raise a bushel of corn. 3 bushels of corn to produce a gallon of ethanol. Plus the energy to plant, irrigate, pick, transport, and refine. Add to that the water used in the refinement process. Anyone who tells you you're helping the environment by running corn based ethanol is a complete idiot.

 

Not to mention it was brought into use by politicians to buy off farmers who are too lazy to adopt sustainable farming methods.

 

But if you like the way your truck drives on it... Go ahead.

[MikeNH]

I ain't doing it to save the world.

[bigsapper]

I posted on the chemistry of E85 previously:

 

http://www.gm-trucks.com/forums/topic/156625-e85-fuel-economy-in-the-toilet/?p=1392701

 

To be clear, unleaded can mean anywhere from 0-10% ethanol. I'm assuming you're not talking about ethanol free (E0), and you are talking about 87 octane E10 (most common/cheapest). On a btu/gal basis (what you pay at the pump), E85 has ~26% less energy content/gal than E10. At $3.30/gal for E10 87oct, this would require E85 to be $2.43/gal or less for break even. A data set of real world comparisons would be a better tool, but this estimate is based on chemistry.

 

Excellent post.

[mike94silverado]

I hate that crap.... If they sold it for 2.00 a gallon that's one thing but when it's subsidized by the government and selling near the price of gas? No thanks

 

 

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