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  1. #1

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    2012 RXPX 260, Need impeller suggestion..hitting 8900 rev limiter

    I currently have installed the Riva SRZ-15/20R. I'm hitting up against my 8900 rev limit in this cooler air, what is the next logical step for impeller mods to stay off the limiter?

    stats from my run yesterday

    8900rpm 15.8lbs
    81.3 mph
    intake temp 86.7f
    water temp 74f
    air temp 60f

    THX!


  2. #2
    SLASHER's Avatar
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    Try a smaller nozzle (83) and repitch to drop rpm ...

  3. #3
    Moderator Snoman's Avatar
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    Re-pitch,adjustable nozzle or adjustable pump cone....Up north here when it gets cooler we use the adjustable rings to choke or open the nozzle for RPMs....also in the cooler weather you may want to watch your AFRs as they will change also..

  4. #4
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by DinoMite View Post
    I currently have installed the Riva SRZ-15/20R. I'm hitting up against my 8900 rev limit in this cooler air, what is the next logical step for impeller mods to stay off the limiter?

    stats from my run yesterday

    8900rpm 15.8lbs
    81.3 mph
    intake temp 86.7f
    water temp 74f
    air temp 60f

    THX!
    Keep running the 15/20R and use the Lucky 13 adjustable pump cone
    http://www.4-tecperformance.com/inde...oducts_id=2355

  5. #5

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    AFR's are rock solid so far...probably a motec thing .

    So just putting the 83mm nozzle how does that effect acceleration/top speed.

    Should I just get another impeller just like the one I have and have it pitched? Save this one for summer...maybe take some pitch out?

    THX GUYS

  6. #6
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by DinoMite View Post
    AFR's are rock solid so far...probably a motec thing .

    So just putting the 83mm nozzle how does that effect acceleration/top speed.

    Should I just get another impeller just like the one I have and have it pitched? Save this one for summer...maybe take some pitch out?

    THX GUYS
    Don't choke it down with an 83mm nozzle. It will affect acceleration.

    Go with an adjustable pump cone. Run no spacers in the summer.... run all three spacers (or more) in the winter.
    There's no need to have two different impellers.

  7. #7

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    How about just raising the rev limit since you have a Motec? A spare impeller or a complete bolt on TUNED jet pump is always a good idea.

  8. #8
    GRF + DashPac:) seadoo02xp's Avatar
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    Your px should already have an 83mm nozzle. Thats the factory size I measured mine the other day

  9. +1 by:


  10. #9

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    Quote Originally Posted by Green Hulk View Post
    Quote Originally Posted by DinoMite View Post
    AFR's are rock solid so far...probably a motec thing .

    So just putting the 83mm nozzle how does that effect acceleration/top speed.

    Should I just get another impeller just like the one I have and have it pitched? Save this one for summer...maybe take some pitch out?

    THX GUYS
    Don't choke it down with an 83mm nozzle. It will affect acceleration.

    Go with an adjustable pump cone. Run no spacers in the summer.... run all three spacers (or more) in the winter.
    There's no need to have two different impellers.
    So your advocating changing the efficiency of the pump to solve the issue. Either making it more efficient thus spinning the impeller easier thus still hitting the limiter or making the pump less efficient thus causing the engine to do more work against additional pump pressure.

    what am I missing? Feels like I have to do something with the impeller pitch first and then play with efficiency with the cone to optimize pump pressure...some combination of the two sounds like the best result.

  11. #10
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by DinoMite View Post
    So your advocating changing the efficiency of the pump to solve the issue. Either making it more efficient thus spinning the impeller easier thus still hitting the limiter or making the pump less efficient thus causing the engine to do more work against additional pump pressure.

    what am I missing?
    Absolutely! You are making the pump more efficient by using the cone.
    Loading the venturi by adding the cone and spacing it rewards does bring down engine RPM, but does not make the pump less efficient... it makes it more efficient.

    Spinning an impeller at high RPM's effortlessly inside the pump actually makes for a less efficient pump. Load the venturi with a cone

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