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  1. #1

    anyone swap a 4 tec in an older seadoo BOAT

    I know it has been done in skis plenty but has anyone tried it in a boat?

    After a friend got a heck of a deal on a 215 seadoo boat I can not stop thinking about wanting one. I like the 4 stroke motors alot and keep dreaming about putting two in something like a 98 speedster. The boats have so much room I think it would be easy to add a few turbos and the idea of two three hundred hp motors in a 16 foot boat gets me excited. A swap would be way down the road but I want to know the options before picking up a boat.
    Just wondering if anyone has ever seen it done.

  2. #2
    espritonsevas's Avatar
    Join Date
    Dec 2007
    in all honesty, the options are the same as the ski, their really isnt anything more difficult, its actually just easier, just double the cost. I can tell you though, you will have without a doubt a 65+ boat if you have 2 300 hp motors in a speedster.

  3. #3
    Water4fire's Avatar
    Join Date
    May 2005
    New Braunfels TX.
    It sounds awesome, but with the two I have woked on it just seams theres just not enough room for two big 4tecs, but it sure sounds good!


  4. #4
    Hydrotoys's Avatar
    Join Date
    Jul 2005
    Mesa, AZ
    What engines are in that boat now?

  5. #5

    Join Date
    Sep 2007
    Pascagoula, MS
    the 98 speedster has twin 800cc 110hp. mine will run 55mph on the GPS with a light load. You would need some kind of trim setup for sure if you are going to put some 4tecs in there. IMO.

  6. #6
    Hydrotoys's Avatar
    Join Date
    Jul 2005
    Mesa, AZ
    Or one rotax 4stroke instead.

    215hp stock, probably same weight or lighter, plus all the aftermarket.

  7. #7
    Join Date
    Aug 2008
    I have a '97 Challenger 1800 with the same twin 800's (110hp). I tend to wonder what this 18 foot boat would do with two of the newer 4 stroke seadoo engines, especially now that there's 510hp available in the speedster 200. I assume you'd also have to change the pumps. Would the intake area of the smaller 2stroke pump be a restriction too? I'm still a Newb with the boat and I have no idea what the guys do when they stick these larger engines into the old seadoo PWCs.

  8. #8
    Any luck with the swap? Did you move forward with it? These are my current plans for my 98 Speedster. Any one actually completed this project?

  9. #9
    shui's Avatar
    Join Date
    Apr 2011
    Montreal, Canada
    its possible to make one but its going to be really expensive...
    dont forget you will need to add some fuel cap in there too... AT the very least you will need 120-150L of gas for double 215HP's

    id just imagine the cost... new rotax engines about 8000$ each (if not more)
    turbo, everything else... 8000$ per engine (turbine, intake grates)
    for 32 000$ its really a new boat... heck. a used 200 speedster... and then you just mod it...

    as for the swap... its possible... but i wonder how it will fair with all the extra weight in the hull...

    (lets say on a newer 150 the cap is about 4persons plus some cargo, (715 pounds.. now that means, you add the weight of a rotax (say 300 pounds. now you have a 1000pound boat capacity... (guessing it would be simillar to the older speedsters.)
    now that makes. 2 rotax are 600 LB (with amost everything attached and such)
    leaves you 400pounds... out of those, you have to take away some to make a bigger fuel tank... say...200pounds?
    (so you have a 160~L tank cap.) nd you have 200 pounds left for passengers and such...)
    in most cases its going to be 1 person... and MAYBE some gear...)

    this is just my opinion on why this project wouldnt work... more luck doing the same to a challenger 180... then you would have enough cap. left for 4 people or so

    (dont forget, your taking away the weight of those old twin engines, but they surely weigh less than a rotax4tec... meaning, even if they both weighed in 300 pounds, you add that to the capacity, but the rotax weight 600 pounds, so really, the capacity of the boat will vary from 200-600 pounds (which is OK))

    but with that much weight, the boat probably will be impractical (getting full of water when decelerating) and so on...

    hope i helped... sorry for the long boring post.. but i think this just wont work out...

  10. #10
    Here's a silly question. First I'll start with, I'm new to everything boat. I just bought a 96 speedster for $500 and can't run the twin or even single 2-stroke on any lakes here in Nevada. I want to do a swap to a 4-tec and was wondering if I can just convert it to a single jet? Is there a better, cheaper alternative? I love these little boats but not a fan of the 2-stroke restrictions. Couldn't pass up the boat and trailer for the price. Thanks! -Brett

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