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Discussion Starter #1
I am looking at possibly boosting my car this summer. I had a boosted sohc a few years ago, before E85 was even available, so we tuned on 91 octane pump gas. I am only looking for 250-275whp on a stock block with block guard and ARP head studs. proper tune and 310's or 440's (whichever my tuner suggests). My question is this. Running E85 with this setup, how bad is the gas mileage really going to decrease over 91 Octane pump gas? I would like to achieve 30mpg still. Is this possible? Or am i dreaming wet?!?

Thanks in advance
 

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92 Civic Hatch
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Im not 100% sure, but you might need bigger injectors than that for E85 to get the number you want. When they tune E85 they appearantly have to use quite a bit more fuel (thus the lessened fuel economy)

At least thats how my tuner laid it out to me. you might be fine with those injectors, might not, but a heads up at least
 

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Yea, youre gonna need at LEAST 750s for that power goal. I would just get 1000s to be sure...

[EDIT] Oh, and on the mileage part. I cant really say for sure. I get 25ish, but my car only weighs 2200 with me, so thats a big part of it.
 

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The mileage all depends on the tune itself and how much lead is in your right foot. I would get 1000s, so that when you build the block to handle more...you'll have that much room to grow.
 

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Del sol
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Personally it will probably be better if you stick to regular gas, your fuel economy will probably be better on 91/93, you also don’t have to worry about different quality of e85 messing with your tune. Also gasoline will be a lot easier to find depending on your state. 275 is too much on a stock block, careful that the block guard doesn’t mess with your cylinders if you’re reusing the pistons.
 

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Discussion Starter #7
The mileage all depends on the tune itself and how much lead is in your left foot. I would get 1000s, so that when you build the block to handle more...you'll have that much room to grow.
I am assuming you mean my right foot. I really only daily drive, but am contemplating boost.

There's a good chance you're going to chuck a rod if you're going for that power.
I thought of that, but was unsure of the power handling capability of the stock rods.

Personally it will probably be better if you stick to regular gas, your fuel economy will probably be better on 91/93, you also don’t have to worry about different quality of e85 messing with your tune. Also gasoline will be a lot easier to find depending on your state. 275 is too much on a stock block, careful that the block guard doesn’t mess with your cylinders if you’re reusing the pistons.

E85 is easy for me to get to. They have it all around me.
 

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Discussion Starter #8
I just want it for a little extra snaz, I do not race anymore as street stuff is too expensive when caught, and the tracks are all too far away.
 

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Stock block will be very hard pressed with that and likely not hold for long if it does.

E85 is sweet stuff, however it sounds like you might just want to stick to 91/93 octane if you're that worried about mileage.

My laser gets about 22mpg on the highway and 14 in the city with E85. My buddy's civic actually gets around 30+ on the highway but gets complete crap in town but has never tested it.

E85 is great stuff though if you want power. And for 250-275whp I'd suggest at least 700cc+ injectors for E85, but I'd just get 1,000s for when you want to go bigger.
 

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I won't reiterate the stock block comments.

E85, in my experience (which is not in performance engines, but flexfuel vehicles), shows a significant decrease in mileage.

What are you currently getting mpg wise?

Again, this obviously has to do mostly with tune and driving style... Hard to figure.
 

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88 ED6
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If unleaded is readily available and you don't really have the need for E85, stick with premium unleaded. It's seems you'd be going through a lot just to say you're running E85. IMO, not worth it.
 

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E85, in my experience (which is not in performance engines, but flexfuel vehicles), shows a significant decrease in mileage.
Even in performance engine I'm going to assume the MPG is significantly lower. Flex-fuel vehicles automatically retune the AFR target for a given lambda value; so it's safe to assume the difference would apply to many vehicles. I mean stoich AFR for E85 is richer than the even a turbo'd unleaded engine under load.
 

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1999 EJ8
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I'm currently running RC 440cc injectors and making around 170whp on E85.

Gas mileage blows, to say the least. I'm sure I could lean it out a bit in the cruising RPM's to increase MPG, but I lack the equipment to tune. Since 90% of my time is spent in town, I see around mid 20's for MPG. Better on the interstate obviously, but I'm willing to bet it's not any higher than 28mpg.

About the only benefit I enjoy is the power increase. Which is definitely noticeable. 5psi on my 15g running E85 feels like 9-10psi on a 15g running 93 octane.

I can't wait to get the Vitara block in there and up it to 15-16psi :TU:
 

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98 Civic CX-T on E85
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i would have to say while your gas mileage does decrease, it really depends on the tuner and dyno as far as how they can compensate for it...for example, my car was tuned on a dyno dynamics load bearing dyno which had the ability to set the dyno to a certain speed and the tuner not have to hold his foot on the gas pedal to keep it there, he would set the dyno at say 40mph and then tune my a/f ratio and timing for that specific speed, they did this throughout several different speeds for regular intown driving to give me the best fuel economy which i am happy to say im still over 30mpg. then they tuned the performance side of it as far as doing regular WOT pulls and adjusting a/f and timing that way...in the end i ended up with a 300whp car that still gets 30+mpg...
 

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What...you all never use the super secret economy pedal under the dead pedal? Remove the dead pedal to reveal the secret of the century!
 

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I think you will need bigger injectors. I'm running 1000cc and get anywhere from 17 to 25 mpg with a boosted d16z6 in my rt4wd wagon. the only downfall for me is the cold weather, it's a pain to start. overall, I'm very happy with running E85. and look into the tax breaks for using it in your state. I get a .50 rebate per gallon in oregon. up to $200. not sure about federal
 

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1988 Honda CRX
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All other things being equal (or equally optimised for each fuel) at the same power level E85 uses about 30% more fuel. Sure you can tune the E85 for economy to get better MPG, but if you put the same effort into tuning premium petrol for economy you will still get 30% better than e85 tuned for economy. It really breaks down to relative prices.

Short story, E85 needs to be 30% cheaper to be cost effective. Even then that does not pay for the higher capacity fuel supply system if required and you do end up with 1/3 less miles on a tankful with a fuel that is harder to buy.

You may need to carry spare fuel, fill up more often or figure a way to increase the size of the tank.

If I was running E85 I would want a 50% at least bigger tank.
 

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95 Honda Civic EX
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I am looking at possibly boosting my car this summer. I had a boosted sohc a few years ago, before E85 was even available, so we tuned on 91 octane pump gas. I am only looking for 250-275whp on a stock block with block guard and ARP head studs. proper tune and 310's or 440's (whichever my tuner suggests). My question is this. Running E85 with this setup, how bad is the gas mileage really going to decrease over 91 Octane pump gas? I would like to achieve 30mpg still. Is this possible? Or am i dreaming wet?!?

Thanks in advance


With a good running stock block & headstuds 250-275whp will be easy to obtain. You will want to run at least a 750cc injector.....and 30mpg?? I think its very possible! but really only going to see that milage on the freeway, around town, short trips, cold starts 18-20mpg. I tuned a RT4wd wagon with a stock block Z6, did 285whp and ran like a champ.

my car has a Built Z6, crower stage 2 turbo cam, 2200cc injectors, E85 and I get 26 mpg on the freeway and 18 in town. If I take alot of short trips/cold starts, my milage go's down big time!

Yes its true E85 pretty much takes 30& more fuel, I have tuned cars on 92oct then switch them over to E85 added 30% more fuel and "BAM" they are almost fully tuned! However you will need to spend some time on the cold starts, adding cranking fuel & post cranking fuel will me almost mandatory. evan without touching the timing most turbo cars I have tuned pickup 20-30whp!!!!:) just by switching to E85, thats been verified with several cars doing before and after dyno pulls on the same day

I think if you have a good tuner and E85 sources close to you then use E85!!
 
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