E85 vs E10(gas+10%ehtanol)

[Ryland]

From what I've read E85 has a fuel to air ratio of 10.5 to 1 instead of 14.7 to one like you would have with gasoline and that adjustment is going to be near instant if your o2 sensor is working right.

[roosterk0031]

Found some ethanol data here

http://delphi.com/pdf/techpapers/2011-01-0900.pdf

By my calculations E85 has 30% less energy than E10, yet the Impala is only loosing about 16% in MPG, seems like it's more efficient with E85.

[brandonppr]

Must be that some cars are just better suited for E85.

I wish they would make the cars to run on E85 only, but I guess there are not enough pumps. If they could run E85 only I think they could do better cost wise than flex fuel or gas cars.


I just filled the first take of E10 today and my millage is up alot from what it was.
I'll have to wait to get a few tanks logged to see what happens.

I was avging about 16mpg E85, my first tank of E10 averaged 26mpg

[roosterk0031]

Originally Posted by brandonppr

Acording to EPA its rated
E85
15 city
18 combined
23 Hwy

Gasoline
22 city
26 combined
33 Hwy

Thats about 44.5% better on Gasoline
Why is there so much differnce?

Actually the EPA E85 ratings are roughly 1/3 lower than E0 ratings. 1/3 or 22 is 7, so 22-7 is 15, 1/3 off 33 is 11 so 33-11 is 22(1 off). I don't think they test E85, they use the 32.8% or so energy difference and round it off.

OOPS: 32.8% is by weight, energy difference per volumne is 28%. Also looking at fueleconomy gov most FFV are reduced by closer to 25% except the Malibu & HHR which are 2 of the few 4 cylinder FFV produced are dinged at around 30%.

[Clev]

Originally Posted by roosterk0031

Actually the EPA E85 ratings are roughly 1/3 lower than E0 ratings. 1/3 or 22 is 7, so 22-7 is 15, 1/3 off 33 is 11 so 33-11 is 22(1 off). I don't think they test E85, they use the 32.8% or so energy difference and round it off.

Meaning of course that they have no incentive to tune the engine for efficiency on E85. After all, if they maximize E0 efficiency, it improves the artificially contrived E85 number, even if the car actually runs like crap on E85.

[roosterk0031]

The 2 FFV cars I've had run the same either fuel, only bad side of E85 is reduced range. I've run E30+ blends in 2 other cars with no driveablity or starting issues.

As I said above my 2 FFV cars burning E85 were actually more efficient in converting chemical/potential energy of E85 into mechanical energy, than they are with E10.

But I think they can still get more out of E85 if they crank up the compression or add a little turbo boost(FFV Cruze?). I'd buy a E85 primary fueled car, that could still limp around (like sports cars that wants 93, but will tolerate 87 with reduced timing).

[Frank Lee]

^Yup.

The bottom line is, ethanol STILL isn't commonly available everywhere and even where it is, it hasn't been widely adopted. That being the case, would you sell engines optimized for ethanol and compromised for E10?

[Clev]

Originally Posted by Frank Lee

^Yup.

The bottom line is, ethanol STILL isn't commonly available everywhere and even where it is, it hasn't been widely adopted. That being the case, would you sell engines optimized for ethanol and compromised for E10?

Of course not. CAFE uber alles, and as long as CAFE uses real-world measurements on E10 and then applies a flat percentage to calculate E85 economy, manufacturers have no incentive whatsoever to try to make an engine work well with both. This would be the case even if E85 was 90% of the market.

[Frank Lee]

It would take a lot more than accurate EPA numbers to get me to initiate an ethanol optimization engine program. It would take widespread availability and widespread demand, neither of which exist in the market. This is yet another example of where the govt steps in to get the ball rolling on something the market initially rejects but years later, embraces.

[trooper Tdiesel]

an engine made for 93 octane and e85 would be a much better set up

making one that runs on 87 and E85 makes no real since. it runs like poooo on E85 in regards to MPGs

ive thought about it but haven't, since i have diesel and beat the gas by-far.

low compression say around 8 to 1 with boost. that would let you run 89 or 93 octane when needed.
or high compression like 11 to 1 mabe a little more, and just barely run on 89 or 93 with out pinging.