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Thinking of going E85

7K views 10 replies 5 participants last post by  WRX-maniac 
#1 ·
Lately I've been thinking of converting to e85. I've been doing some research about the cons of e85 but really haven found much. So I was wondering if anyone on e85 could educate me a little more.
 
#2 ·
Nasioc has an e85 thread. Saw some good info on there but you gotta search really hard. What specifically would you like to know? ...or what do you now already? What's your build plans? Maybe someone more knowledgeable can give you some specific answers with some more info.
 
#4 ·
Right now with my current mods I would need bigger injectors and retune at minimum. I know this. How does e85 make more power? I got that it burns cooler and you need more of it. If I go e85 is my fuel system going to tank in 5 years from e85. Basically some pro and cons of e85.
 
#5 ·
You will also need a higher flowing fuel pump.

The knock resistance of e85 allows for a much more aggressive tune. You are able to make more power through more aggressive timing as well as more boost pressure. Turbo spool will be improved as well because the increased volume of fuel creates an increase in exhaust gasses.

Your fuel system will be fine, many people have been running it for several years without problems. I will say however if you leave the car sitting for extended periods of time with e85 in the rails it has a tendency to eat away at the injector seals. Luckily they are relatively inexpensive and fairly easy to replace. (You also don't want to leave it sitting because ethanol absorbs moisture over time, which degrades the quality of the fuel)
 
#6 ·
Thanks for the info mainframe. I wonder what kinda gains would one see from converting to e85? I would want a 93 tune also. How would that work with e85 in your tank? Would I have to wait till my gas light came on then put 93 in and flash the 93 map? I wonder how much e85 could be in your tank before it was safe to switch to a 93 map?
 
#7 ·
On my 2L wrx I made 45 more whp and 50 more ftlb of torque on e85 over 91. You tune for 91 (93) first with only 4-5 gallons in the tank, then you run down to where the gas light comes on and you have maybe 1 gal left in the tank... fill with e85 and then tune for that. Ideally, if you tune for e85 with ~1 gal 91/93 in the tank before fill up, when you run full e85 in the tank you will have a bit of a saftey margin.
 
#8 ·
On a well sorted car we typically see about +50whp and +70wtq around here. My tuner has seen a lot of issues with people not emptying their tank well enough before switching maps (resulting in blown engines).. so his school of thought is you should drain the tank entirely before switching. That's why I installed an ECA on my car (and I log regularly).

For what it's worth, there's still quite a bit of fuel left in the tank when the light comes on.. I have driven 73 miles before with the light on ( and never ran out of gas).
 
#9 ·
How much did your mpg decrease going e85? One of the reasons (and probably the only reason) is the fact I have one gas station within <20 miles that carry e85. On top of that I would have to jump on a toll road to get there. :(. If this car still was my DD I wouldn't even want to talk about e85 but now that the Rex is not the thought definitely entertains me.
 
#11 ·
Yup, all the info given in here is accurate. I wish I was in your shoes to at least have the option to go e85. Closest E85 fill up for me is 45 mins away. :( If you have the resources and a good tuner, DO IT. You won't be disappointed. :thumbup:
 
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