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  1. #1
    Jarrett's Avatar
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    RXP-X - Low Octane Fuel?

    The sticker on the ski says 91 recommended and 89 minimum. What happens if you put 87 or less octane gas in it? Does the ECU compensate for this at all? What changes would you notice?


  2. #2
    REID2168's Avatar
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    never do that.................... BUT if u HAVE to cause your caught on a BIG LAKE..........get ready for MORE HEAT and LESS RPM's and i wouldnt run WOT at all..........maybe DETONATION BABY....... knock sensor or NOT! BET!!!!!!!!!

  3. #3

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    They will run on it if you are in pinch and that is all you can get. You will have decreased performance acceleration and top end and will loose some rpm's on the top end due to the knock sensor working like Reid said to protect the engine.

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    Jarrett's Avatar
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    If that's the case, that could be my problem. I was running some really suspect gas on my run yesterday that I got from a backwoods Marina two weeks ago. It didn't have an octane rating on the pump at all, but I had to use it in a pinch and now its sat for a couple of weeks as well. I ran almost all of that gas out of the ski yesterday. I'm refill it with good 93 gas and see what happens. Thanks.

  5. #5
    Jarrett's Avatar
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    My only concern is that I had an RXT with me running the same gas in the same weather and it was running great. 8180 RPMs, higher than its run before.

  6. #6
    Laxcrazy23's Avatar
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    i was in a jam and needed gas. 87 was the only thing around and skin ran like garbage. was only 2 gallons. got back home. put Ultra 93 in it and ran it out.

    Ski runs fine now.

  7. #7
    GTI SE 155
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    Octane is just a function of the fuels ability to supress pre-ignition (knock), it doesn't give you "more" power. High octane simply allows a high performance engine to use all it's designed-in performance. Most, if not all, modern 4-stroke motors have knock sensors which should dial back ignition timing automatically to supress any knocking or pinging. All this does is reduce engine output. I presume SeaDoo uses knock sensors?

    Almost any modern, high-compression, high performance engine (auto, boat, ect) can run adequately on 87 octane (or even lower) quality gasoline without damage. You'll just have lower output.

  8. #8
    Mod less, ride more! troyheb's Avatar
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    Quote Originally Posted by fastexas View Post
    Octane is just a function of the fuels ability to supress pre-ignition (knock), it doesn't give you "more" power. High octane simply allows a high performance engine to use all it's designed-in performance. Most, if not all, modern 4-stroke motors have knock sensors which should dial back ignition timing automatically to supress any knocking or pinging. All this does is reduce engine output. I presume SeaDoo uses knock sensors?

    Almost any modern, high-compression, high performance engine (auto, boat, ect) can run adequately on 87 octane (or even lower) quality gasoline without damage. You'll just have lower output.
    +1

  9. #9
    Looped's Avatar
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    Quote Originally Posted by fastexas View Post
    Octane is just a function of the fuels ability to supress pre-ignition (knock), it doesn't give you "more" power. High octane simply allows a high performance engine to use all it's designed-in performance. Most, if not all, modern 4-stroke motors have knock sensors which should dial back ignition timing automatically to supress any knocking or pinging. All this does is reduce engine output. I presume SeaDoo uses knock sensors?

    Almost any modern, high-compression, high performance engine (auto, boat, ect) can run adequately on 87 octane (or even lower) quality gasoline without damage. You'll just have lower output.
    +1
    Just to add...
    The Octane just changes the speed of the burn. 91 octane actually has less "power" than regular if your motor is designed for regular gas in the way your thinking of "power". The power being how much fuel was burned at optimum timing. At higher compression ratios, the regular gas won't burn when it is supposed to and will cause detonation, or pinging. Thats where the higher octane comes in.

  10. #10
    GTXX's Avatar
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    Quote Originally Posted by Jarrett View Post
    My only concern is that I had an RXT with me running the same gas in the same weather and it was running great. 8180 RPMs, higher than its run before.
    a 215 RXT has less boost and a different timing curve than your X, therefore I suspect that it would not be affected the same by low octane fuel.

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