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Thread: Speed vs RPM

  1. #1
    Beagleman62's Avatar
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    Speed vs RPM

    Does anyone have any ideas on speed vs RPM and the need to repitch the prop? I have my rpm's up to 7990-8050 depending on the temps. It doesn't seem like you get that much more speed with the higher rpm's.
    I'm wondering if repitching the prop would help take advantage of the higher rpm's? I have held off sending my pump and prop to Impros untill I see some results from people who have sent theirs. Since this ski came out last year, I have yet to see anyone get good results from changing the prop or getting the stock one repitched.
    Any ideas?


  2. #2

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    I have the impellar repitched and the wet pump mod. My rpms are usually between 7900-8000, sometimes a little over 8 and sometimes a little under 7900.

    Now, the mid range acceleration definetely feels much stronger. I hit 70.9 on low fuel Saturday evening and probably would of went past 71, but I had no idea I was that close so I made a turn instead of continuing straight. I ran consistently over 70 with 70.4 about the norm. Sunday down 1 bar of fuel from full I went 70 I could pull some 68.8s to 69 sitting on the seat straight up.

  3. #3
    Beagleman62's Avatar
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    Would this help?
    ULTRA 250X VENTURI NOZZLE WITH INTERCHANGEABLE RINGS

    Our reduction nozzle is the key to tuning your boat to its utmost performance. Insert a larger diameter ring for more RPM or acceleration power. Or, for more top speed install a smaller diameter ring. Nozzle includes three stainless steel rings of your choice. Choose three rings sizes: 82mm - 85mm, to customize your nozzle.

    Stock nozzle size is slightly over 82mm
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  4. #4
    Dubz1's Avatar
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    Correction, just looked up at R-Rated, they offer 4 sizes.
    Last edited by Dubz1; 04-21-2008 at 05:31 PM. Reason: Correction.

  5. #5

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    Quote Originally Posted by Beagleman62 View Post
    Would this help?


    I have begun to wonder if the nozzle rings may help

  6. #6

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    Performewr kit from R&D site
    PERFORMER KIT
    72-72.5 mph @ 8050-8100 RPM

    STAGE 1 PERFORMANCE KIT
    73 mph @ 8100-8150 RPM


    So is more rpm better? Looks like maybe pitching for around 8100 rpm is best, which goes back to maybe the impros stock mod or stock impellar is the best.

    Input?

  7. #7

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    So has any rec rider broke 73? It looks like a pulley will be required, but what else to get there? I do not think a stock ride plate ski will get there. Prelim numbers says a riva plate ski with wedge will be required. I hope I am wrong and I hope Tn finds the right prop or a pitch that works well.

  8. #8

    Exclamation impeller testing for impros

    I did all the impeller testing from impros and if you get the modded impeller with the gear-oil like I have in my post you pump will have less drag and spim even more rpm...........

    Have Dave at impros mod the impeller................................you wont be dissapointed.

    Holeshot is really HOT!

    Hurricane

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