Quantifying ethanol effect on mpg - list your results

[Phantom]

I read a while ago that blends between 20E-45E could actually give better MPG but the amounts differed on different cars. I cannot find the original pdf it might be at home but a quick search came back with:
http://www.ethanol.org/pdf/contentmg...yStudy_001.pdf
http://www.ethanol.org/pdf/contentmg...se_12507-1.pdf
*This is bias due to the author of the study but I was thinking that the other document I had found was from a different organization but I could be wrong about that.

[bwilson4web]

Originally Posted by Phantom

I read a while ago that blends between 20E-45E could actually give better MPG but the amounts differed on different cars. I cannot find the original pdf it might be at home but a quick search came back with:
http://www.ethanol.org/pdf/contentmg...yStudy_001.pdf
http://www.ethanol.org/pdf/contentmg...se_12507-1.pdf
*This is bias due to the author of the study but I was thinking that the other document I had found was from a different organization but I could be wrong about that.

Those were the papers that motivated me to study E30 in the Prius only the results were so modest and the savings so small, the labor it took to 'home brew' E30 didn't make sense. That is why I came to the conclusion that it might be useful but the margin of error was too large and I didn't see a clear, winning strategy involving E30.

But I also think it is important that results are vehicle specific and the engine control laws have a lot to do with whether or not it can 'tune' to optimize performance either on a miles/gallon or the riskier, $/mile.

Now this is pure speculation but it may be possible that a properly tuned, Atkinson cycle might be able to exploit a higher, effective octane rating of alcohol blended fuels to improve efficiency. I do know at maximum power, my 1.5L Prius engine will 'tune' to exploit 93 octane gas in a maximum power, hill climb. But it isn't clear that this could be achieved at less than maximum power.

GOOD LUCK!
Bob Wilson

[Allch Chcar]

Originally Posted by roosterk0031

2002 Chevy Suburban 1500 4x4, wife driving, 5.3 FFV. Davidk0031 fuelly.com

E10 15.2mpg 30 tanks
E85 12.4mpg 35 tanks (-18%)

1998 Dodge Stratus, 2.4 auto, preliminary data, in order they were collected this earlier spring. (assumed E85 was 85% could have been 70%, drops blends about 5%) SGII of no value as has to be recalibrated so tank to tank is only way to check mpg.

E30, 2 tanks back to back, 28.4 mpg (-11%)
E0 2 tanks back to back 31.9 mpg
E10 3 tanks back to back 30.5 mpg (-4%)
E25 1 tank* 33.5 mpg
E44 1 tank 30 mpg
E0

* - Fluke tank maybe, but I'm driving better and warm outside.

You really should invest in an Ethanol test kit and post your results for each tank. I believe they can be had for $15 or so. I'll link one later if I can. E85 is a big difference from E70, -18% is stellar for E85 and above average for E70. That would also put your numbers off by several percentage points for all of your results .

[rmay635703]

Originally Posted by Phantom

I read a while ago that blends between 20E-45E could actually give better MPG but the amounts differed on different cars.

It differs A LOT by car. My Buick was unaffected up to about 40% ethanol. At the time e85 was about 50% cheaper than e10 so it was a no brainer.

My cobalt looses about 2-4mpg on e40 which ends up not being worthwhile given the $.80 price difference.

I have not done as much testing on the cobalt as the buick. My Dodge also looses a bit of mileage above 30% 2-3mpg (which is huge going from 18-21 to 14-16). My Dodge has in the past gotten nearly the same but I think it was only about a 20% ethanol mix I was messing with back then. Another nice side effect was gaining massively more FE than I lost on the first tank I filled with normal gas, though it did miss a bit I was happy with 22mpg.

Its worth noting that you really don't have to blend your own fuel per seh.

The local ethanol gas station sells E10, E20 and E85. Just add a little of e10 and a little E85 to get what you want.

[justjohn]

Thanks guys, good info coming in.

If you could give the year of your cars and any engine details that might be pertinent that would be great, as one of the things I would specifically like to put some data behind is whether or not older cars take a bigger hit from ethanol. Don't forget to post pure gas numbers if you can get them!

I myself am most interested in E10-E15 vs pure, but the high ethanol mixes are interesting as well.

[rmay635703]

Originally Posted by justjohn

Thanks guys, good info coming in.

If you could give the year of your cars and any engine details that might be pertinent that would be great, as one of the things I would specifically like to put some data behind is whether or not older cars take a bigger hit from ethanol. Don't forget to post pure gas numbers if you can get them!

I myself am most interested in E10-E15 vs pure, but the high ethanol mixes are interesting as well.

My cobalt is an 010, the buick was a 98, the dodge is an 01. E10 VRS pure is going to be hard to get accurate data on since normally (at least here) only Premium 93 octane is ethanol free which makes it rather moot points.

Also around here a lot of the ethanol gas from 3rd parties is 89 octane (aka 87 gas mixed with ethanol) sadly most of the big boys are mixing 84 octane with ethanol to save money which I believe is why we are seeing an increase in crap MPGs from ethanol fuel.

Mixing the lowest possible grade gasoline with ethanol is a recipe for failure.

Heck, might as well mix half a tank of #1 bunker oil with ethanol, not much different.

[roosterk0031]

Best tank ever, on E0 35 mpg, but previous tank of E24 at only 30 mpg is still cheaper per mile. Running another tank of E0 to see if it holds true, my driving is still improving slighly but 55 mph on cruise and some coasting in neutral when effective, tiny amount of P&G in town, 95% miles are hwy at 55 mph.