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  1. #1

    Question Can you turbocharge a carburated ski engine?

    As the title states, can you turbocharge a carburated engine? I need a good winter project and have been considering throwing a turbo on the 96 SL700. I know in theory it's possible as turbo chargers have been around before fuel injection even existed. My motor was rebuilt with forged wiseco pistons so im curious what size (mm) turbo could I get away with?

    What about electrical, will the CDI box work with a turbo?>

    Or am I just crazy as it will cost more then the ski is worth to make this work?

    Thanks for any info!


  2. #2
    PolarisNut's Avatar
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    Quote Originally Posted by 03stage2 View Post
    As the title states, can you turbocharge a carburated engine? I need a good winter project and have been considering throwing a turbo on the 96 SL700. I know in theory it's possible as turbo chargers have been around before fuel injection even existed. My motor was rebuilt with forged wiseco pistons so im curious what size (mm) turbo could I get away with?

    What about electrical, will the CDI box work with a turbo?>

    Or am I just crazy as it will cost more then the ski is worth to make this work?

    Thanks for any info!
    Yes, you definitely can. Its been talked about here before...LOTS of obstacles that will need to be overcome...If you're not familiar with turbo 2 strokes, you're looking for a blown motor. Not sure how you'll work with the CDKII carbs...You need to find a way to raise the fuel pressure about 5psi over boost pressure, or completely enclose the carbs (you'll need an electric pump). You also will have issues since the 700 uses a wet pipe...you can't send water through the turbine of the turbo. You will also have to water cool the turbo, or you'll start a fire in the engine compartment. Also will have to come up with a way to pressure lube the turbo bearings with engine oil (not 2 stroke oil). Then come up with all the piping for the hot and cold sides...Like I said, not an easy task, even for the most mechanically inclined.

    Never personally seen a turbo 2 stroke watercraft. I'm more familiar with turbo 2 stroke snowmobiles...a 600cc twin cylinder running ~10psi boost on 110 race fuel will make 200hp.

  3. #3
    Norwegian Wiking Trond's Avatar
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    Quote Originally Posted by 03stage2 View Post
    As the title states, can you turbocharge a carburated engine? I need a good winter project and have been considering throwing a turbo on the 96 SL700. I know in theory it's possible as turbo chargers have been around before fuel injection even existed. My motor was rebuilt with forged wiseco pistons so im curious what size (mm) turbo could I get away with?

    What about electrical, will the CDI box work with a turbo?>

    Or am I just crazy as it will cost more then the ski is worth to make this work?

    Thanks for any info!
    Yes you can!! But... you need to rebuild the carbs to handle pressure (build a box around them), or else the boost will blow the gas out of every avalible hole. You could use a already pressureised carb coming from the old volvo 240 turbo (stromberg). You could also put one big single carb on the other side and let the turbo suck trough it. This is not the best way to go tho, but it works.

    Cool projeckt!!
    I like turbo

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    If you are looking for a winter project, put a three cylinder Polaris engine in the hull. The 1165cc engines will fit with a little relocating of the engine mounts.

    If you want even more power, you can enlarge the displacement with larger cylinders, or even a stroker crank. Maximum size seems to be about 1450cc, but that is quite a project engine to build from the crank case up.

    The classic method of 'turbocharging' a 2-stroke is to use tuned exhaust pipes to boost the density of the fuel+air charge inside the cylinder. Tuned exhaust pipes create an effect similar to turbo charging, using the exhaust energy to boost power.

    There are some tuned pipe sets around for the two cylinder engines, but they tend to be rare finds.

    A more modest power boost can be had by fitting a pair of larger cylinders onto your engine, and possibly adding a stroker crank.

    There are a few 1,000cc twins around, but they are normally found in the stand-up Octane machines, which only go full throttle for a few seconds at a time.

    What do you want to achieve?
    Acceleration, top speed, uniqueness...

  5. #5
    I've been thinking about this too. The part that concerns me are the reeds. You cant really be boosting all 3 cylinders at once due to the reeds for each cylinder needing to be opened and closed at different times. Unless I'm missing something.

  6. #6

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    use a old leaf blower build the box around the output

  7. #7
    Lot's of good info folks.

    Quote Originally Posted by K447 View Post

    What do you want to achieve?
    Acceleration, top speed, uniqueness...
    I have an alterior motive. You see I have a supercharged car that I paid to have built. I have done some small things and the tranny on the car, however I have never touched the motor. I bought the ski to work on and get some basic hands on engine mechanical experience.

    I wanted to go turbo as I dont like them on the street, however I think in a pwc it would be extremely fun. That late turbo punch in the water would have to be a blast!

    However I'm new to all this so I need to do something that will not only give me some better mechanical understanding, but also be doable within my limited means.

    Oh yeah, I dont want to spend a ton of money....

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by 03stage2 View Post
    ... I wanted to go turbo as I dont like them on the street, however I think in a pwc it would be extremely fun. That late turbo punch in the water would have to be a blast!

    However I'm new to all this so I need to do something that will not only give me some better mechanical understanding, but also be doable within my limited means.

    Oh yeah, I don't want to spend a ton of money....
    Well, if you don't want to spend a lot of money, then you won't be turbo charging your PWC

    If you want to feel turbo lag in a PWC, find a Honda R12 model, which has a factory Honda turbo. Some folks liked (or tolerated) the boost lag, most did not.

    PWC performance is as much about low end torque as it is peak HP output. Unlike a geared or clutched land/road vehicle, the jet pump is directly driven at crank shaft speed, so the engine needs to develop torque to spin up the impeller, which is constantly loaded by the water.

    Polaris also made a turbocharged PWC, the MSX 110 and MSX 150. It was designed to minimize turbo lag, and spool up rapidly.

    On the water, you often need to modulate the throttle in response to water conditions. Uneven and delayed engine response makes the ride more difficult, as you would be compensating for the boost lag.

    Most PWC enthusiasts look to maximize torque and instant engine response, and then maximize peak RPM output.

    A PWC engine is actually a very highly stressed engine environment, as in a PWC (or a boat), you can open up the throttle and hold it there for many minutes at times. Most land vehicles do not operate the engine at peak RPM and HP for more than a few seconds at a time.

  9. #9
    casey67's Avatar
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    The 2 stroke engine uses minimal parts (it's light weight/power ratio is why it was used in PWC)
    4 stroke engines are better adapted for turbo or super chargers( because of the camshaft and valves for intake and exhaust) Sorry to say the Seedoo 2 stroke with the intake valve system might be better for forced induction.

    I think Detriot deisel had a 2 stroke with super sharger.

  10. #10
    PolarisNut's Avatar
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    Quote Originally Posted by casey67 View Post
    I think Detriot deisel had a 2 stroke with super sharger.
    Yes, the roots blower was REQUIRED to make the 2 stroke diesels run. They were also turbo charged.

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