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I noticed that my local gas station is now offering E85 fuel. Not only is it cheaper by about 30 cents per gallon but I hear that it is about 103-105 octane.

I just read an article where it works particularly well on turbo cars and I was wondering about switching over and having my car re tuned to run it. In an article in Import tuner magazine, they were able to get an extra 66whp out of their Mitsubishi EVO just by switching over due to the ability to tune it. (They did use a stand alone which in all fairness they could have tuned some more power out of the regular gas) but basically due to the higher octane, they could run it leaner, have more aggressive timing, and run higher boost. Even without the ECU they picked up about 35whp.

What do you think? Any downside? Other than availability of E85, it is cheaper, burns cleaner, and if I can pick up another 20-30whp, it sounds pretty good to me. I am not sure how available it is in other parts of the country if I want to take a trip but I think it is becoming more prevalent.

Also, my fuel ratios are tuned to about 11.1 at full boost. I was talking to a friend who worked on race turbo engines and he thought that was awful conservative and running too rich. I don't want problems with blowing up my engine, so I want a little margin there but do you think it is a little rich? Obviously I could gain a little if it was leaner. I guess if I had it retuned, I would consider tuning it for the E85.
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E85 will give you more power, but it'll all depend on whether or not your build can stand to make that much power, on our 460RWHP turbo car a lot of things broke at that level, the transmission for instance is going to be a very weak point.

E85 probably isn't cheaper though, but if you're just looking for power i doubt it matters. Lots of Evo guys run it for some extra go. Lotus made some excellent inroads with it too.

I doubt there is a lot of power to be made leaning it out, but its tough to say really without seeing the tune/dyno/MBT etc.

how much boost are you running ?
 

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It may be cheaper, but you get worse fuel economy. Determine the $/mile for a true comparison.
 

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It may be cheaper, but you get worse fuel economy. Determine the $/mile for a true comparison.
Ya, generally your able to get more power becuase it burns cooler then gasoline thus you are able to put more fuel in per combustion. While I think its great for motorsports, I really dont see it becoming long term for consumers...niche market maybe.
 

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It may be cheaper, but you get worse fuel economy. Determine the $/mile for a true comparison.
E85= $2.50ish gallon
VP C16 race fuel = $12+ /gallon.

No comparison....
 

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here's my dynochart comparing my 91 octane tune vs E85 tune and i have very minimal mods and i'm on the stock ECU. Both fuel maps were tuned on the same day. Guess the only thing you need to worry about is if the car can handle the add'l power

 

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Pics of a Mitsu Evo motor running on E85 and also pics of it running 91 & 100 octane...Note, this is not my car...
Thread discussion here:
My motor on E85... - evolutionm.net

Pulled the head today...

This is my personal motor after approx 10k miles on E85, 62k on the motor:







The reason why we pulled the head, pushing coolant on 3 and 4:







This is the same motor at approx 35k, 2years ago, before it saw any E85 at all, just 91 and 100oct:

 

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...as heavily-modified as your car is, derek, you've probably already replaced the affected parts, but i believe ethanol can damage the stock fuel pump, possibly along with other assorted bits and bobs...
 

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On FI engines that are used occasionally, there are benefits given the price to octane ratio. Comparing E85 to leaded C16 is kind of silly, but comparing it to 100-104 octane unleaded race gas (generally $6-7/gal) is reasonably fair. By that metric E85 is certainly much cheaper by volume, even though you use a good deal more given the much lower energy content.

The drawbacks generally include:

- Need a purpose built fuel system with massive injectors.
- Need to be able to tune for it properly, which for most people means an aftermarket ECU. That can create ODBII issues for people.
- Alcohol tends to eat rubber and certain plastics. Though, as you'd be building a fuel system anyway, you'd have to replace everything so it's somewhat moot.

As applies to an Elise/Exige, the biggest problems are largely capacity related. If you're making lots of power, you're going to be using a lot of E85. An effective ~30% reduction in range will make the car almost useless for anything other than local driving, unless you live in an area that's very dense with E85.

That of course ignores the larger problem-- eventually E85 is going to go away for common use given the entirely ridiculous energy and resource requirements needed to produce it, and you'll either be stuck retuning for gas, or retuning/converting to another alcohol. So, for me anyway, the only application would be a track toy, and I don't know that saving a few bucks a gallon versus race gas would be worth the investment in a huge fuel system and the relative inconvenience of having to haul my own fuel around to track days.

Your mileage may vary.

Oh, and incidentally...

Also, my fuel ratios are tuned to about 11.1 at full boost. I was talking to a friend who worked on race turbo engines and he thought that was awful conservative and running too rich.
It's a little rich, but pretty far from "awful conservative" unless you like blowing up engines. 11.5 is about ideal for a FI engine. You can push your luck closer to 12:1, but chances are something will bite you running that lean if the wrong set of circumstances happen at the wrong time. You're not going to pick up a huge amount of power leaning out from 11-11.5 to 11.5-12, but you are going to significantly increase the potential for bad things happening. If an engine builder is saying that, and knows you're talking about a FI engine, he must not mind blowing things up on someone else's dime.
 

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On FI engines that are used occasionally, there are benefits given the price to octane ratio. Comparing E85 to leaded C16 is kind of silly, but comparing it to 100-104 octane unleaded race gas (generally $6-7/gal) is reasonably fair. By that metric E85 is certainly much cheaper by volume, even though you use a good deal more given the much lower energy content.

The drawbacks generally include:

- Need a purpose built fuel system with massive injectors.
- Need to be able to tune for it properly, which for most people means an aftermarket ECU. That can create ODBII issues for people.
- Alcohol tends to eat rubber and certain plastics. Though, as you'd be building a fuel system anyway, you'd have to replace everything so it's somewhat moot.

As applies to an Elise/Exige, the biggest problems are largely capacity related. If you're making lots of power, you're going to be using a lot of E85. An effective ~30% reduction in range will make the car almost useless for anything other than local driving, unless you live in an area that's very dense with E85.

That of course ignores the larger problem-- eventually E85 is going to go away for common use given the entirely ridiculous energy and resource requirements needed to produce it, and you'll either be stuck retuning for gas, or retuning/converting to another alcohol. So, for me anyway, the only application would be a track toy, and I don't know that saving a few bucks a gallon versus race gas would be worth the investment in a huge fuel system and the relative inconvenience of having to haul my own fuel around to track days.

Your mileage may vary.

Oh, and incidentally...



It's a little rich, but pretty far from "awful conservative" unless you like blowing up engines. 11.5 is about ideal for a FI engine. You can push your luck closer to 12:1, but chances are something will bite you running that lean if the wrong set of circumstances happen at the wrong time. You're not going to pick up a huge amount of power leaning out from 11-11.5 to 11.5-12, but you are going to significantly increase the potential for bad things happening. If an engine builder is saying that, and knows you're talking about a FI engine, he must not mind blowing things up on someone else's dime.
I'd say comparing E85 to C16 is a good comparison since some other boosted guys i've seen have got the same/more power on E85 versus C16.

-a lot of people are running E85 on just an upgraded Walbro fuel pump
-a lot of subbies/evo's are using the OEM Ecu. Just gotta know how to change the maps properly. If the lotus ECU can be tuned for a different type of gas, like C16, then there's no reason why it can't be tuned for E85
-I've been daily driving E85 for 18 months and no issues with fuel lines eating away that i know of

Stoich for E85 is 9.7. Gasoline stoich is 14.7....
 
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