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Discussion Starter #1
Having just gotten my base tune file from OVT, I was talking with a friend who`s got a modified Benz who runs E85. I emailed Mat just to see if we could move forward with an E85 tune map should I choose to, and I`ve learned it`s available in far more spots locally than I first thought. So a couple of questions for those who are running it, and in particular those who`ve been tuned for it.

(1) I heard fuel economy is worse with E85. I suspect that`s bogus. Any experience here? (and fwiw, please no speculation. Looking for actual experience here)

(2) Will the car run on 93 in a pinch if it came to it?

(3)Did you genuinely notice a difference between it and regular gasoline?

I am all for a cleaner burning fuel. I drive a *lot*, and while I`m no activist, I do try to be environmentally conscious when I can.
 

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(1) I heard fuel economy is worse with E85. I suspect that`s bogus.
Why do you suspect that? Ethanol has less energy content than gasoline, so of course fuels with higher ethanol content are going to result in lower fuel economy.

If you don't believe me, read what the federal government has to say about it here, or here's an Edmunds article about a back-to-back test in a flex-fuel pickup truck (tl;dr: a trip ended up costing more with E85), Car & Driver agrees, and finally Popular Mechanics points out that E85 is great for filling up rental cars since it's cheaper by the gallon even though the fuel economy is lousy, but that's not your problem after returning the car. :|
 

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Mightycarmods did a couple good videos about E85. Now they are by no means scientists but they do shed some light on the pros and cons of using E85. The energy output of the corn stuff isn't as good as proper petrol. I think E85 has an output 65-70% of regular unleaded gasoline. So to get the same power you'll need more corn juice to get the same performance. It runs cooler is cheaper and much cleaner so there are benefits. Granted you will be filling up more so maybe not that much cheaper.
 

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Discussion Starter #4
I wouldn`t be filling up with E85, just two or three gallons mixed in is the suggested amount. I guess I could see how this tank goes with the new tune and then burn through an E85 mix before getting my next flash to get a direct comparison...
 

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I wouldn`t be filling up with E85, just two or three gallons mixed in is the suggested amount. I guess I could see how this tank goes with the new tune and then burn through an E85 mix before getting my next flash to get a direct comparison...
Are our cars fuel lines, pumps and injectors cool with E85?
 

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Discussion Starter #6
Are our cars fuel lines, pumps and injectors cool with E85?

I just watched an hour long video about the long term effects of E85 on a vehicle not specifically designed for it. At 108K miles entirely on E85 they tore the motor down, took out the fuel pump and lines, and removed the catalytic converter and cut it in half. It was all in better shape than a similar vehicle with 98K that was run on gasoline. I`m still on the fence about it, but it sure looks good on paper. There are a couple of folks on here that have the E85 OVT tune. I was kinda hoping they`d chime in.
 

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My friends run on e85 on their modified turbo cars which helps them achieve higher "pump gas" horsepower, dont see a reason to run it for a DD that wasnt meant for it. It will get worse mpg than regular gas, but I suppose the tradeoff is that it is cheaper per gallon.
 

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Discussion Starter #8
My friends run on e85 on their modified turbo cars which helps them achieve higher "pump gas" horsepower, dont see a reason to run it for a DD that wasnt meant for it. It will get worse mpg than regular gas, but I suppose the tradeoff is that it is cheaper per gallon.

On a stock, unmodified vehicle I don`t really see the benefit, other than cleaner emissions. But several of us here have had our ECU tuned to take advantage of the high compression and squeeze out the power that mazda left on the table. No, the SkyActiv 3 is never going to be a big horsepower player, but I can`t say I`d mind getting everything it has hidden in there. I can only imagine what kind of results I`d have gotten from my 300ZXTT with E85!

And cheaper per gallon has a rub as well.Putting tuning and HP aside, If the higher consumption outweighs the lower cost then the only benefit is back to cleaner emissions. Not that it`s a bad thing :)
 

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I avoid ethanol at all costs. Ever since there were reports of MINIs with damaged fuel pumps due to only 10% ethanol, and expanding/deforming nylon fuel tanks on motorcycles, I only use ethanol-free fuel in my vehicles. It attacks various plastics, can damage aluminum, and its hygroscopic nature means it will absorb water, particularly if you live in a humid environment. Given time, it will also separate from the fuel, resulting in a lower octane than intended. Anyway, I'm sure the Mazda3 is fine with at least 10% ethanol, but I still avoid it whenever possible.
 

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So a couple of questions for those who are running it, and in particular those who`ve been tuned for it.
(1) I heard fuel economy is worse with E85. I suspect that`s bogus. Any experience here? (and fwiw, please no speculation. Looking for actual experience here)

Your fuel economy will go down due to the richer stoichiometric ratio of ethanol vs. gasoline. When running ethanol, it simply takes more fuel to hit AFR targets. I noticed around 2-3 more mpg when running around 4-5 gallons E85, rest 91.


(2) Will the car run on 93 in a pinch if it came to it?

No, that would be a bad idea. The tune you get will be optimized for the E85 blend, which would mean a more aggressive tune. Switching back to 93 on the E85 tune will cause knock, due to the lower overall octane rating of the 93 fuel. You will also get highly rich AFRs as the fueling will be set to compensate for higher fuel trims needed for E85. Its best to flash back to the 93 file when using that gas. You should also have the tank nearly empty during re-fill.


(3)Did you genuinely notice a difference between it and regular gasoline?

It did help a bit in my case, and I used up to 5 gallons, rest 91. Ethanol has a dual effect. Not only does it boost octane, but it also produces a cooling effect on the intake charge. In hot climates, the effect will be more dramatic. Do not use in freezing temps though, as it may hamper cold starts, and be aware that some states use winter E85 in order to help cold starts (closer to E70). Compared to a 93 tune, you might only see realistically another ~10 whp. More compared to 87, 91, etc... I believe 4-5 gallons of E85, rest 91 produces around 95 octane and close to 30% ethanol in the blend (assuming the gas has 10%, which is what most 91-93 blends have aside from Shell V-Power which is 0%).
 

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God, I wish I could find a local supply of pure gas.
Shell V-Power 91 is pure gas. Its sold just about everywhere, but isn't exactly cheap. Most brands of gasoline on the market use 5-10% ethanol, regardless of the octane level.
 

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I also ran a 4 gallon blend for awhile. There was a noticeable difference in performance, butt dyno.....I saw a drop in mpg of 4.

I do tend to get on it though.....fun to drive.

After Mazda recalled and required PCM update, the E85 blend tune was having some issues....triggered CELs and sluggish.

Not sure if that was ever ironed out by OVT.

I still have full tunes for 87 and 91, no issues with those after OVT updated my tunes with new PCM updates from Mazda recall.
 

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Shell V-Power 91 is pure gas. Its sold just about everywhere, but isn't exactly cheap. Most brands of gasoline on the market use 5-10% ethanol, regardless of the octane level.
I wish. VPower around here is all 93 octane 10 percent corn juice. BP offers pure gas at 91 octane, but I have to go to Wisconsin for it. So, sometimes I do.

Sent from a Samsung that doesn't explode.
 

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It runs cooler is cheaper and much cleaner so there are benefits.
Running cooler might not be a good thing for direct injection engines. I'm not sure how its done, but I remember reading somewhere that the heat build up by the injectors helps keep carbon deposits down.
 

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Discussion Starter #16
So now that we`ve had a couple of folks who have actually used it and had their tunes to support it, I`ll ask this: in regard to both reliability and performance, is it worth it? Is it a viable option for long term?

I have seen compelling evidence that the detriment it is supposed to be on fuel systems is hogwash. I also believe that if there were a measurable negative effect it would be all but erased with a 4-1 blend (3 gallons to a tank).
 

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Just as mentioned above, many Asian countries run high ethanol blends on the same cars, just tuned differently. There shouldn't be any issues with going from E10 standard gas to an ~E30 blend containing 4-5 gallons E85. Modern cars now come with lines and fuel system components that resist ethanol. I would run a fuel tank treatment product once in a while to remove some of the water that may potentially build-up in the tank. If you re-fill often, there won't be much time for phase separation to occur.
 

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I wish. VPower around here is all 93 octane 10 percent corn juice. BP offers pure gas at 91 octane, but I have to go to Wisconsin for it. So, sometimes I do.

Sent from a Samsung that doesn't explode.
I'm surprised Shell does that in some states, and not others? In Canada, they claim that 91 V-Power contains 0% ethanol across the country.
 

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It may have more to do with emissions regs across the country. They do very, but I'm no expert on that. The area I live in tests biannually for emissions, but two counties out and most of the rest of the state doesn't at all.

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