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  1. #1

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    Read with caution! (fuel)

    Im not suggesting anyone run this in there ski`s but on the 300x it seems people running the scom are Octane (RON) cautious I know in my area there are 3 different fuels at the pump 87 / 89 / 93 premium Although its not widely available every where we do have E-85 (85% Ethanol) I just learned somthing very interesting about it and that is the true octane(RON) of E-85 is actually 94-96 plus it holds its octane supposedly much better than the NON ethanol fuels now with that being said im not going to go out and fill my 300x up with the stuff but i found this to be very interesting information..Some of you may have already known this but i had no idea.Now i know why when i was complaining about ethanol one forum member told me that i needed more of it it runs richer. So what would be the negatives of running E-85?


  2. #2
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    E85 burns much cooler but requires about 30% more fuel, it also absorbs water which in a marine environment is a bad thing. The good news is that if tuned for it you can eek out more power because you can run more timing with it, that coupled with the cooler burn nets more power safely. You can't just drop in and go though.

    Sean

  3. #3

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    Quote Originally Posted by smokeysevin View Post
    E85 burns much cooler but requires about 30% more fuel, it also absorbs water which in a marine environment is a bad thing. The good news is that if tuned for it you can eek out more power because you can run more timing with it, that coupled with the cooler burn nets more power safely. You can't just drop in and go though.

    Sean
    I was thinking maybe add 5 gallons to a tank of 93 premium but im not really a big risk taker when it comes to my ultra.

  4. #4
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    It will be worthless unless you tune for it, and in this case it would actually have the potential to harm the engine. At a minimum you need a wideband o2 sensor and a fuel pressure regulator. Ideally you would have a fuel sensor to tell you what the ethanol content is because e85 is not always e85, a fuel controller and a spark controller.

    If you do it, do it right, if you don't do it right, don't do it.

    Sean

  5. #5
    Moderator beerdart's Avatar
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    What octane rating are you referring to?

  6. #6

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    Quote Originally Posted by beerdart View Post
    What octane rating are you referring to?
    (R+M)/2

    I have been trying to educate myself on fuels and there additives what they do and dont do.Im no chemist by any means but after seeing the 300x`s with the no#1 pistons buned up on here i started looking at ways to possibly raise my octane above the 93.(Not saying thats what caused the failures) I have since learned that race fuels are not = i was told to stay away from race fuels that are oxygenated, VP,sunoco,renegade they all have Leaded , Unleaded , some oxygenated some are not,,,much like E-85 the oxygenated fuels take a lot more of it,,they burn cooler but require more fuel to prevent Lean conditions,,all comes down to tune,since the 300`s ECU want compensate for bad fuel or accidental low octanes my goal is to use a race fuel/pump gas combo to give me a solid 96 octane mix. May not even be necessary .
    Last edited by jeff007; 05-05-2013 at 07:08 PM.

  7. #7
    nicjak's Avatar
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    good luck but I wouldn't go there..

  8. #8
    Self Confessed Day Dreamer toomanytoys's Avatar
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    Sean is right.

    Bottom line is don't use it. You need to tune for it and the amount of Ethanol changes slightly. You need an ECU that can pick up the changes too. Haltech have just made a sensor for their ECU but that's for Haltech.

    If you use it, you will run lean. Forget about trying to raise Fuel Pressure too. You'll most likely need injectors to get the extra 30% you need, and that a tune (new ECU) anyway.

    Stick to 93/98 RON and be happy. Don't mix fuels either. If you can only get low octane, you need to take extra fuel. Not worth risking it IMO.

    Cheers, Mal.

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    Quote Originally Posted by toomanytoys View Post
    Sean is right.

    Bottom line is don't use it. You need to tune for it and the amount of Ethanol changes slightly. You need an ECU that can pick up the changes too. Haltech have just made a sensor for their ECU but that's for Haltech.

    If you use it, you will run lean. Forget about trying to raise Fuel Pressure too. You'll most likely need injectors to get the extra 30% you need, and that a tune (new ECU) anyway.

    Stick to 93/98 RON and be happy. Don't mix fuels either. If you can only get low octane, you need to take extra fuel. Not worth risking it IMO.

    Cheers, Mal.
    I never knew these 4 strokes were so sensitive to fuel... I was planning on doing a few more WOT runs this year, but im not going to with 93 ron! I can get any kind of racing fuel i want local but not knowing which one to use is another story. Ive always thought as long as you run a higher octane than you need you would be fine.Im a little skeptical about race fuel with LEAD in it and also high contents of oxygenates in it. I dont know what effects it might have.I would think any fuel with a 100 octane will reduce heat and prevent detonation much better than 93 ron.JMO

  10. #10
    Self Confessed Day Dreamer toomanytoys's Avatar
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    95 RON, 91 MON (I think) is the recommended/minimum for the 300x. I only use 98 RON because that's the default octane rating where I live. It's really only 91 and 98 RON here.

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