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  1. #1
    REID2168's Avatar
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    Best Changeable Nozzle???????

    fellas who is currently the best supplier to get a NEW adjustable nozzle from i obviously want an 81mm,82mm, and 83mm rings and solid equipment. i just figured out after my buddy bought one abd the dude said it would increase RPM by 500 that u have to have it then repitch to get these rpm's u guys are obtaining. hit like a TON of BRICKS.

    CURRENTLY:8320/8340 w/Stage Three kit, NO NOZZLE and 77.6 GPS
    THEN: Add Nozzle adds 500 RPM makes 8820/8840 rpm then....
    THEN: Add 2mm of pitch on my 10mm Riva15/19R pitched prop and i got 12mm then i drop RPM by 300 hopefully and...
    THEN : should go to 8520/8540 and be PERFECT and pick up some speed..

    i hope this is CORRECT???? it all came to me after he said (my buddy Doobie the guy that bought the nozzle yesterday i was talking to) the guy from Riva says it increases RPM by 500 and my buddy argues with him because my buddy thinks he knows after reading a thread that it ONLY increase 80 rpm at a time but thats BETWEEN 81,82,83mm nozzles i assume since stock after measuring is approx 87 to 87.5mm when adding one of theose is the 500 rpm increase he speaks of. i figured it out as soon as he said what the Riva guy said it just hit me BIGTIME. im a NEWBIE dudes. I havent even had a boat a year yet 2006 RXP blown charger washers and impeller and 2007 RXP blown charger washers but my buds i did the work to is above figures and should really run after prop adjustments and nozzle addition. guess we will see. any thoughts about my new found knowledge would be appreciated. thanks for any help fellas.


  2. #2
    Site Admin Green Hulk's Avatar
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    You will NOT gain 500 RPM's by going to an adjustable nozzle.

    To get the best speed out of your ski pitch the impeller to run its max RPM with the 81mm nozzle.

    The best place to buy it is in the online store right here!
    (see my signature)

  3. #3
    REID2168's Avatar
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    then how does it work???????????? cause just telling me to change the nozzle and pitch the prop DOESNT make sense even if its the right yhing to do i can appreciate that part but i need to UNDERSTAND whats going on.

  4. #4
    REID2168's Avatar
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    maybe u r saying that because of the REVLIMITER it wont go to 8800+ RPM so i can understand that part but is my theory correct maybe? if it could rev that far. REVLIMITER is what it hits I assume then is what u r saying but u pitch to 2mm into the prop and that keeps the engine from hitting the rev limiter. am i getting it now Jerry???????

  5. #5
    REID2168's Avatar
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    revlimiter being 8600 rpm i assume with a ROTAX racing ECU

  6. #6
    Vern's Avatar
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    Adjusting the nozzle size affects thrust and pump efficiency, and there is a bit of a relationship to the size of a skis intake grate/cavity ... but seriously, nobody can explain why certain skis 'like' certain size nozzles. For unknown reasons, most RXP modders have found their best top speeds doing exactly what Jerry stated ... install an 81mm nozzle, then bend the trailing edge up or down to achieve the optimal rpms for your setup/ECU. For stock ECUs, most of us aim for 8100, for ECUs with an 8600 rpm limit, most aim for 8500 rpms, and continue to tweak their impellers until they get the rpms right. Nobody can explain why ... but it works.

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