Considering E85 for my Supercharged Lotus Exige

[SoCalSteve 0]

Hey folks,

Since I've got to retune my car to pass emissions and function properly with the aftermarket super charger, i have to run two separate ECUs. So i'm considering swapping to e85. my mechanic says that i will pay less in fuel, but lose mpg. currently it looks like a 14% gain in cheaper fuel offset by his estimation in an 8 mpg (30%) loss in fuel economy. except for the much better performance and better emissions, it would appear to be a less than optimal set up.

 

opinions on which way to go?

[gasisoutrageous 85]

California is pretty strict on emissions, and I know those smog checks can run pretty expensive. I would recommend E85 myself, for a few reasons...

1) As I've said elsewhere on this forum, E85 tends to have much more stable pricing than gasoline.

2) You'll have better smog check results, and the older the vehicle, the more stringent the pass requirements.

3) California tends to have better price spreads than those of us out east because of the higher price of gas over there (especially in LA and San Diego)... and depending on the fuel economy difference with your vehicle, the price spread (or difference) might make it worth it to run E85.

 

Basically what I usually say when someone is unsure, is I ask them what their priorities are in terms of fuel use. Which is a bigger concern to you... fuel economy and your pocketbook, or the environment and pollution?

[BJoe 28]

I'd be more likely to go E-85 in your case than with my Jeep as it currently sits.  If you have to use premium, there will be a considerable difference in price, and with a boosted motor, the intercooling effect of the E-85 would help performance, especially during hot summer weather.  I noticed the latter last summer with the N/A Pentastar V-6 in my 200, and that motor is capable of being run on just plain old 87 octane if I want to!

[85racer 0]

Not knowing the specifics about your engine, I see the base compression for many model years is 11.5:1. Adding a super charger is going to push compression ratio high enough to the point where E85 works at its best. Plan for a loss in MPG but don't be surprised if you gain MPG if your getting around 14.5:1 to 16:1 compression. Just an observation from other conversing with other E85 racers.