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  1. #1
    Impulses's Avatar
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    RESULTS NO LOGIC, PROP and RPM

    Many of you have posted their results with the props and rpm and as you can see from the table there is no logic no:

    RPM TUNED............PROP SIZE.................SPEED....................REAL RPM

    8.375 12,5/19 74,5 mph 8.300

    8.375 15/20 71 mph 8.160

    8.375 12,5/21 75 mph 8.140

    8.375 stock 70 mph 8.120

    8.350 stock 76 mph -----

    8.500 15/20 74 mph 8.250

    All these data have been taken from their publications in Greenhulk.
    But as you will see no Tinen same no logic, all these engines based on 260 (2010-2013)


    I think this should not be a matter of luck or magic, I think you should install X RPM X prop without fear of failure.


    According to those who say that altitude and temperature affect the engine ... but then a stock pwc run very differently in Canada than in Florida and that is not so.


    Something to say about all this?


  2. #2

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    We all try to do the same thing your doing. You can take two exact ski's, put the exact parts on them and one will be faster. Could be all kinds of factors. Production variations in in the hull, tolerances in the motor, minor prop variations...the list is endless. Then take into account geography, salt vs fresh water...the list continues. 5 minute WOT open runs vs 10 second WOT runs with a 20mph tail wind. General sand bagging and fudging that I'm sure never happens around here. I'd say at best it's a loose guide to do what your doing...but I wouldn't loose sleep over it.

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  4. #3
    dpracing's Avatar
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    Quote Originally Posted by DinoMite View Post
    We all try to do the same thing your doing. You can take two exact ski's, put the exact parts on them and one will be faster. Could be all kinds of factors. Production variations in in the hull, tolerances in the motor, minor prop variations...the list is endless. Then take into account geography, salt vs fresh water...the list continues. 5 minute WOT open runs vs 10 second WOT runs with a 20mph tail wind. General sand bagging and fudging that I'm sure never happens around here. I'd say at best it's a loose guide to do what your doing...but I wouldn't loose sleep over it.

    +1 !!

  5. #4
    Impulses's Avatar
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    thanks for answering and collaborate:


    So according to you where should I start considering that I have already some modification (riva gen 3, SS riva intake grate, air filter 4 ", catch can)
    datalogger + tuned + 8.375 rpm fuel pressure regulator?
    15/20r with stock prop or prop (that I have in the box)
    that I can expect speeds around?

  6. #5
    Mod less, ride more! troyheb's Avatar
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    Quote Originally Posted by Impulses View Post
    So according to you where should I start considering that I have already some modification (riva gen 3, SS riva intake grate, air filter 4 ", catch can)
    datalogger + tuned + 8.375 rpm fuel pressure regulator?
    15/20r with stock prop or prop (that I have in the box)
    that I can expect speeds around?
    With stock prop and 8375 rpms, I would say around 74-75 mph.

  7. #6
    HP raises real fast with both RPM and MAP

    HP is what pushes a boat thru water.

    Put a straight edge on the bottom of 4 boats and they are all different.

    Check the angle of the two trim tabs and the ride plate compared to the botom of most of the fiberglass.

    The props get nicks as do the wear rings.

    Long hulls tend to be easier to slide thru water.

    Light hulls tend to be easier to slide thru water. A light rider helps.

    Peak readings on the GPS verse celebrated GPS vs the dash that tends to be 1.5 MPH optimistic.

    Andy

  8. #7
    See http://www.go-fast.com/boat_speed_predictions.htm

    Hull/Prop/Plate/Nozzle combinations that produce a higher constant make more speed with a given amount of HP.

    Also see http://www.greenhulk.net/forums/showthread.php?t=207765

    Andy

  9. #8
    Impulses's Avatar
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    Quote Originally Posted by whittlebeast View Post
    See http://www.go-fast.com/boat_speed_predictions.htm

    Hull/Prop/Plate/Nozzle combinations that produce a higher constant make more speed with a given amount of HP.

    Also see http://www.greenhulk.net/forums/showthread.php?t=207765

    Andy

    You are too technical for me to understand.I apologize for not understanding what you bother to explain.
    8 - [

  10. #9
    GRF + DashPac:) seadoo02xp's Avatar
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    Quote Originally Posted by Impulses View Post
    Quote Originally Posted by whittlebeast View Post
    See http://www.go-fast.com/boat_speed_predictions.htm

    Hull/Prop/Plate/Nozzle combinations that produce a higher constant make more speed with a given amount of HP.

    Also see http://www.greenhulk.net/forums/showthread.php?t=207765

    Andy

    You are too technical for me to understand.I apologize for not understanding what you bother to explain.
    8 - [
    He is saying there are just too many variables to be able to guarantee what speed or rpm you will reach. Every ski is different. You are on the right track with the mods you have. Maybe a prop adjustment and or tuning adjustment and you will have a nice reliable fast setup.

  11. #10

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    Quote Originally Posted by Impulses View Post
    thanks for answering and collaborate:


    So according to you where should I start considering that I have already some modification (riva gen 3, SS riva intake grate, air filter 4 ", catch can)
    datalogger + tuned + 8.375 rpm fuel pressure regulator?
    15/20r with stock prop or prop (that I have in the box)
    that I can expect speeds around?
    What was your ski running stock? Knowing this will tell you if you have a fast 1 or slow 1 right off the bat. I road a friends 2012 that ran 65.8 mph stock at 8040 rpm-- I am told his is on the slow side. If I ran your 8375 rpm on his ski with his stock impeller, I would guess it would run 70 +/- .5.

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