I have been reading up on the ins and outs of running E85 lately. All my cars require premium gas and its such a pain in tha arse. I learned a few things about running e85 such as:

1. Requires more e85 than regular gas would
2. Need bigger injectors if converting for e85
3. Need a hotter sparkplug if converting
4. Need to lengthen spark pulse (to spray more fuel)

My theory (asuming a d16z6 motor) is to keep stock injectors, upgrade to a hot plug (Bosch platinum 4+) and simply lower compression, either on pistons or a low comp headgasket. Target a 8.5:1 cr. Granted you would take stock hp from around 125 to around 90 ish. But in a goal of a fuel freindly daily it doesnt really matter. I used to have a 5th gen civic 4dr automatic with a d15z1 swap (due to blown d15b7) wich had roughly 92hp but was fine in that size of a car. Would a wideband rich/lean reading still be accurate for running e85? I know just dropping e85 on a non-converted car causes the car to think its running lean (is it really?). I have tested a %70 mix of e85 and regular 93 and did get a CEL 1 (o2) which I guess means its lean. After restarting the car the code is cleared. Please keep the flaming to yourself. Just some random thoughts...

 

Higher compression correlates to higher thermal efficiency, so I wouldn't drop it to 8.5:1. E85 has a higher effective octane rating than pump gas, so you can raise the compression and tune accordingly.

I also hope you realize that you'll need to rework your entire fuel system if you want to run E85 for an extended period of time.

 

not going to work, but I'll have to explain later

 

my theory is to reduce air consumption per combustion cycle instead of raising the amount of fuel needed. That part makes sence to me, but then again, so does the whole higher compression needed for a higher octane gas. I guess that is a "catch 22"... hmmmmmm, still thinking....

 

Rather than dive into the motor, work it from the fuel side of the equation.
Find a programmable ECU solution and have a new fuel map tuned for E85.

An E85 map will need to be richer than the OEM map, so do not expect an increase in fuel economy. Also, keep in mind that you will not be able to run anything other than E85 after this tuning is completed.

Frankly, unless you've got a guaranteed supply of dirt cheap E85 for years, I wouldn't bother. The couple hundred you spend on an ECU retune will take months if not years to pay back.

 

Exactly.

 

Lowering the compression wouldn't necessarily reduce air/fuel consumption because you aren't changing the stroke of the piston. You need approximately 40% more fuel to run E85 than gasoline. This means you would have to reduce the displacement of the engine or increase the amount of fuel by about that much. You could buy some 440cc injectors and throw them on there. And the car would run E85. But without a tune it would run on the rich side and it would be really rich on gasoline. You also need to keep in mind that the extra fuel means worse fuel economy. Generally E85 gets 20-25% worse mileage than gasoline. So unless you can get E85 for 25% less you will actually lose money. There are all kinds of advantages to running E85 on a boosted track car but for a daily driver it's just not practical. I use a moates 2-timer to switch between e85 and gas on my car. I'm getting about 33mpg highway on gas and around 25mpg highway on E85. If you do the math you'll find it's more expensive for me to drive around on E85. If you still want to run E85 you will need the following.
1. 440cc injectors
2. moates 2-timer or equivalent
3. a good tune for both fuels
4. possibly new fuel lines depending on the year of the car and condition of current lines.

 

don't do it. e85 is a scam, anyways.

 

I know it's OT, but I agree if we're strictly talking corn-based ethanol.
Biomass, cellulose and switchgrass-based ethanol has a much better yield for the amount of energy used in production. But ConAgra has the money to lobby Washington, so they get to write our energy policy. :run:

Pardon the interruption; I'll get off my soapbox. h:

 

E85 costs more anyway, why bother?