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What happens if I add one Gallon E85 to a full Tank

Discussion in 'Gen 2 Prius Main Forum' started by Ralphmc, Apr 13, 2006.

  1. Ralphmc

    Ralphmc Mr Hybrid

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    Guys, I have a question. Here in TN - Nashville, we only have one E85, and no E10 Filling station. Is it possible to add one gallon of E85 to not exceed the E10 mixture of the regular fuel. I know it sounds strange that some one would want to just stop and buy 1 gallon of fuel. I would simply buy as much as two Gallons in a Spare cannister, and put one gallon in the tank.

    Your advice is appreciate.

    Thanks Ralph
     
    #1 Ralphmc, Apr 13, 2006
  2. mikepaul

    mikepaul Senior Member

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    Since MTBE is being phased-out, you WILL be getting ethanol mixed into your gas soon, marked E10 or not. The news the other day claimed ALL cars can use E10. http://autorepair.about.com/b/a/220059.htm seems to back that up. So, if you boost the ethanol percentage beyond 10% you are apparently looking for trouble, but 85% of 1/12th of a tank isn't that high.

    Me, I'm not thrilled to see what ethanol costs are going to do to the price of 'gas', but when the tsunami is going to sweep you away anyway why run?...
     
    #2 mikepaul, Apr 13, 2006
  3. hawkjm73

    hawkjm73 New Member

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    A large number of us run quite happily on E10, so that part will be fine. If you do the solution percent math, you will need 7.5 gallons of E0 per one gallon of E85 to end with E10. I usually get about 8.5 gallons per fill on a one-pip-flashing stop, so that would be pretty easy. I would suggest a change to your proposed methodology, though. Stop and get your container of E85, but don't put any in the tank yet. Go to the regular station, put in your one gallon of E85, then finish filling with E0. This sould provide a more reliably mixed tank of gas. Be aware that E10 will produce a somewhat lower gas milage then E0, though the metrics are unreliable. Some see the difference, others don't.


    Here's my math if you want to know.

    x = gallons of E85 -> 15% gas
    y = gallons of E0 -> 100% gas
    x + y = gallons of E10 -> 90% gas

    0.15*x + 1.0*y = 0.9*(x+y)
    0.15*x + 1.0*y = 0.9*x + 0.9*y
    0.1*x = 0.75*y
    x = 7.5*y
    one gallon E85 = 7.5 gallon E0
     
    #3 hawkjm73, Apr 13, 2006
  4. richard schumacher

    richard schumacher shortbus driver

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    Why do you want to do this? If you get the fuel tank mix wrong it might possibly start to degrade parts of the fuel system.
     
    #4 richard schumacher, Apr 13, 2006
  5. Ralphmc

    Ralphmc Mr Hybrid

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    <div class='quotetop'>QUOTE(richard schumacher @ Apr 13 2006, 09:07 AM) [snapback]239065[/snapback]</div>
    hawkjm73 - Thanks for the info.

    Richard, just to get more ahead of making use of alternative fueling. My approche should be: drive tank to 30-50 m past 1st blink. At this point the "bladder" will hold in excess of 7.5 gallon of fuel. I will then add 1 gallon of E85, and fill up the rest with the "bad" stuff (E0). So even if I only get 8 gallons in the remaining empty space I am still ahead 15% right?

    I think even over time - the mix will not be in favor of the "85% or more" it will be in favor of the "85% or less" Ethanol.

    Don't think I'll go wrong here.

    One thing does strike me thou; does ethanol and regular fuel not separate under specific conditions, like water and oil for example. So that now the sudd of Ethanol is at the bottom of the tank and the mix actually becomes E99... ??

    Ralph
     
    #5 Ralphmc, Apr 13, 2006
  6. DonDNH

    DonDNH Senior Member

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    Alchol and gasoline are what is referred to as miscible; a chemistry term that means two liquids will mix together. Alcohol and gasoline will not separate over time.
     
    #6 DonDNH, Apr 13, 2006
  7. richard schumacher

    richard schumacher shortbus driver

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    The problem is that they don't mix instantly. If you try to mix them in the tank, blobs of unmixed E85 will exist for a time and perhaps get sucked into the fuel pump.

    I think your intentions are noble but retailers in all large cities will start selling gasohol/E10 on 1 May. Better just to wait two weeks.
     
    #7 richard schumacher, Apr 13, 2006
  8. Ralphmc

    Ralphmc Mr Hybrid

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    <div class='quotetop'>QUOTE(richard schumacher @ Apr 13 2006, 01:16 PM) [snapback]239233[/snapback]</div>
    Richard, thank you that was what I had thought too, since somewhere in physics class a few years (centurys) ago I had learned something like that, and just was not sure if it is still true. And I believe it would be a better Idea to wait for too.

    Ralph
     
    #8 Ralphmc, Apr 13, 2006
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