Considering an E85 Experiment

[Frank Lee]

Ahhh, you have boost! Your engine should love this stuff!

[Ladogaboy]

That's the plan!

[drmiller100]

for mileage, ethanol likes about the same air fuel ratio as gasoline.

for HORSEPOWER, you can run as much as 7 or 8 to one. The extra fuel supercools the air charge much like Nitrous does, allowing more air into the cylinder, making more power.

[Ladogaboy]

@ drmiller100: Not to be a bother, but can you cite any sources for that? Everything I've read puts E85's stoich at just under 10:1. I understand running 7-8:1 for power, as that is the same concept as running rich with gasoline (usually 10-11:1) for power. But in terms of stoich, I thought that complete burn off is complete burn off. So rather than the 14.7:1 for gas, E85 has ~9.7:1. I know that you can obtain better economy by going beyond stoich, but everything I've read (this is in terms of gasoline) states that leaning out any further than 1.2 lambda doesn't do a whole lot.

[serialk11r]

Going further than 1.2 equivalence I'm guessing is to cut pumping loss by a little, but after 1.2 the flame temperature drops past what it would be at stoich or something so the gains are smaller.

[Frank Lee]

Just put on 272 miles with E66:
1.0g E10 = .1g E + .9g regular
15.0g E70 = 10.5gE + 4.5g regular;
=10.6g E + 5.4g regular; 16.0g total;
=E66

I know I started with an empty tank because I literally ran out of gas on the way to the station. I only put 1g reg in because I didn't like their prices, then 15g E"85" @ $2.90/g, saving over $11 vs filling up the day before.

I presume it was actually E70 due to the time of year, but at 70+ degrees out it seems summer has arrived.

No issues, not even a CEL flicker. At end of 272 miles, gauge is sitting just over 1/2; call that 8g burned = 34mpg. Winds were light and variable, not necessarily favorable, cruised between 53-58mph.

34 mpg would be a good number for this car on regular. Perhaps the accessory drive mods helped a bit...? Perhaps E85 isn't the road to ruin?

[drmiller100]

Originally Posted by Ladogaboy

@ drmiller100: Not to be a bother, but can you cite any sources for that? Everything I've read puts E85's stoich at just under 10:1. I understand running 7-8:1 for power, as that is the same concept as running rich with gasoline (usually 10-11:1) for power. But in terms of stoich, I thought that complete burn off is complete burn off. So rather than the 14.7:1 for gas, E85 has ~9.7:1. I know that you can obtain better economy by going beyond stoich, but everything I've read (this is in terms of gasoline) states that leaning out any further than 1.2 lambda doesn't do a whole lot.

first, ethanol is lighter then gasoline, and injectors inject via volume, and stoich is normally measured by mass.

so if you squirt pure ethanol vs gasoline with an injector, you will find mileage is off about 20 percent, or, another way to put it, you need to squirt about 20 percent more ethanol then gasoline to make an engine run happy.

if it were truly 10:1 vs 14:1, your numbers would be 40 percent different.

my numbers are based upon personal experience with about 50 cars and LOTS of other people who have really tried it.

[shovel]

Originally Posted by drmiller100

if it were truly 10:1 vs 14:1, your numbers would be 40 percent different.

.

I'm not entirely sure I'm understanding you here, but maybe because percents are funny things..

14 is 140% of 10, but 10 is 71.43% of 14 (or about 28-29% different)

[Ladogaboy]

Originally Posted by drmiller100

first, ethanol is lighter then gasoline, and injectors inject via volume, and stoich is normally measured by mass.

so if you squirt pure ethanol vs gasoline with an injector, you will find mileage is off about 20 percent, or, another way to put it, you need to squirt about 20 percent more ethanol then gasoline to make an engine run happy.

if it were truly 10:1 vs 14:1, your numbers would be 40 percent different.

my numbers are based upon personal experience with about 50 cars and LOTS of other people who have really tried it.

Ok. I was under the opposite impression. As I was understanding it, ethanol is denser than gasoline, but it contains about 30% less energy per volume. But, since you need ~40% more ethanol per volume of air (to maintain stoich), the ethanol would produce slightly higher amounts of power per a given amount of air intake.

I don't have any personal experience (obviously), but I am basing this on what I've read. One of the most complete sources I've come across at this point is here: Converting to E85 (ethanol fuel) - Turbobricks Forums

[Ladogaboy]

I'm still considering making this jump, but I have cause to be leery right now. According to everything I've read, the ECU will try to maintain its lambda settings, regardless of which fuel is used; however, because my car is turbocharged (and especially because it is performance tuned), the current fuel delivery system wouldn't be able to supply enough E85 at high levels of boost to keep up with the incoming air. I don't typically drive in that range, but I'd rather not go critically lean at > 200% load and > 20 psi of boost.

I might need to make some adjustments first, and I'm considering making a dedicated tune specifically for running E85. I'm going to ask some tuners with specific knowledge and experience on the subject before I start to move forward with this.