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Thread: RPM and 4-Tec

  1. #1

    RPM and 4-Tec

    I have a question. I have been riding 2 stroke snowmobiles for 30 years. I will be getting a Seadoo soon and am psyched for the 4-tec engines. I have a question though, and I know they are obviuosly two different engines. Everyone on here seems to be RPM crazy and want high numbers. I have seen some threads where they have their ski screaming to 8800rpms or more. I have seen many other rpm #'s listed too. My question is: Is there an optimum rpm for the 4-tec engine to run at? With my sled, there was a target rpm of 8150. More than that and it was overrevving resulting in power loss. ANything under that was also not max power. I also understand with mods the rpm can change, but is this still a general principle or does more rpm just flat out mean more power?

  2. #2
    JFizzleJR's Avatar
    Join Date
    Aug 2005
    It all depends on the engine management governing your craft. A stock 215 HP Seadoo has optimal power around 8100 RPMs. A 255 HP X machine seems to be around 8000. Add an aftermarket ECU and they have a different 'zone' (usually 8500, but depends on what you buy). A full EMS allows for many more revs. Remember that when increasing your RPM limit, you need to take the necessary precautions by upgrading the proper engine components (valve train, injectors, etc.).

  3. #3
    ok, cool thanks. Thats about what I thought. I think I was just a little confused because so many people are running modded stuff so the readings of rpms are all a bit different.

  4. #4
    Kiwi spanner handler
    Join Date
    Dec 2007
    Christchurch NewZealand
    with the supercharger more revs = more boost thats why they go so good at 8550 instead of the stock 8100.

  5. #5
    Very true, I forgot about that. Boosted will be fun! My buddy just put a turbo (I know its a bit different than a SC) on his 4-stroke snowmobile to bring it up to 220HP. That thing climbs anywhere. Thanks, guys. I look forward to getting on the water...soon.

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