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E85 and 93 MPG differences?

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Old Oct 6, 2013 | 09:05 PM
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Default E85 and 93 MPG differences?

Been looking into E85, and reading says that E85 will hit the MPG hard. Some more reading shows that with the right tuning the difference will be rather small. With ample tuning, what kind of differences are people getting?
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Old Oct 6, 2013 | 09:09 PM
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Tune can mitigate mileage loss to an extent, but E85 has lower energy density. So there will always be a loss in fuel economy no matter how hard you work on the tune. That said, I've pulled down 23mpg highway on 50% E85, 50% 91 octane when my old truck had a 4.8 in it. Weighed about 4800 or so. There was about 1000ft drop in elevation over 100 miles, so flat ground mileage may have been 22ish. Just some info for you.
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Old Oct 6, 2013 | 11:12 PM
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Thanks for the info. Just trying to see if the E85 station with 70¢ cheaper gas would be "cheaper" or not
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Old Oct 7, 2013 | 08:03 AM
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I run it 50% in my car at times for the performance gains. It comes out even on the cost. You won't be saving any money with it. At least that was my findings. I lost @ 15% of my mileage and that is about what the price difference was for 50% mix where I live. It did run stronger and with a little more step though. I wouldn't contest it gave me much actual gains in power (probably just 100 octane), but it did run better. I have a high mileage car so I need all the help I can get.
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Old Oct 7, 2013 | 08:13 AM
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Best to calculate fuel economy in miles/dollar instead of mpg when making this switch.
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Old Oct 7, 2013 | 08:46 AM
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I'm running 2 gallons per tank in the DD right now and watching the numbers on it, but gonna give it a few more tanks before I really start doing the miles/dollar like you mention smokeshow.
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Old Oct 7, 2013 | 10:58 AM
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daily drive on e85 straight. went from 32.5 mpg on 93 to @24.1-25.1 mpg on e. but car is a completely different animal and worth it imo. Switched it back to 93 for a weekend and car felt so slow went back to e 85 right away.
just an idea on the tune difference.
cruising timing was @42-43 degrees on 93 52-53 on e85 (throttle response is so much better
17.5 lb of boost 15-16 degrees timing and an 11.4 afr on 93
17.5lb of boost 25-27 degrees of timing an a 12.0-12.2 afr on e85
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Old Oct 7, 2013 | 11:45 AM
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Originally Posted by smokeshow
Best to calculate fuel economy in miles/dollar instead of mpg when making this switch.
this.
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Old Oct 9, 2013 | 10:18 AM
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Compare it to 100 octane prices and it is totally worth it
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Old Oct 9, 2013 | 10:33 AM
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I don't plan on going anything that I can't get within 10 minutes of places I see myself going. Right now just looking at e85, or 93, or 93+meth, or 87+meth. Meth done right, meaning pulse width modulated valve based on fuel injector duty cycle, not based on WOT or vacuum/boost. Not worried too much about the last horsepower, just more about getting around with some power for the most "effecient" money.
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