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  1. #1
    Yellowsierra's Avatar
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    Stock Impeller vs 15-20R

    I was wondering what the rpm drop would be when going from a stock impeller to a 15-20R. Im turning 8100 rpms now with the stock prop but im about to add a new charger wheel, intercooler and ect.

    Thanks

    Justin


  2. #2
    Moderator Snoman's Avatar
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    It all depends on how extreme your gonna go with your mods..If your gonna do a full stage 2 or 3 then they should be close or might be a little high..Anything below a stage 2 or 3 they will be to low and you will loose performance..

  3. #3
    Yellowsierra's Avatar
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    Quote Originally Posted by Snoman View Post
    It all depends on how extreme your gonna go with your mods..If your gonna do a full stage 2 or 3 then they should be close or might be a little high..Anything below a stage 2 or 3 they will be to low and you will loose performance..

    Right now i have the X-charger, 4" intake and free flow exhaust. My rpms are 8,100. Thats 3,100' elevation. Im going to get the Rude X-charger udgrade when it comes out. That should probley be another 200-300 rpms. Plus im putting in a XS intercooler kit. If I knew this prop would take away 300-400 rpms then it would work perfect. I guess you can also ways pitch the impeller but it would be nice to have a rough idea.

    Can you use the riva adjustable nossle to control the rpms as well? What size is the stock nossle on the rxp's? I know the Riva nossle kit comes with 83mm, 82mm and 81mm rings. Im guessing you lose around 100 rpms with the 1mm smaller ring.

    Justin

  4. #4
    Moderator Snoman's Avatar
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    Quote Originally Posted by Yellowsierra View Post
    Right now i have the X-charger, 4" intake and free flow exhaust. My rpms are 8,100. Thats 3,100' elevation. Im going to get the Rude X-charger udgrade when it comes out. That should probley be another 200-300 rpms. Plus im putting in a XS intercooler kit. If I knew this prop would take away 300-400 rpms then it would work perfect. I guess you can also ways pitch the impeller but it would be nice to have a rough idea.

    Can you use the riva adjustable nossle to control the rpms as well? What size is the stock nossle on the rxp's? I know the Riva nossle kit comes with 83mm, 82mm and 81mm rings. Im guessing you lose around 100 rpms with the 1mm smaller ring.

    Justin

    Justin,
    With your Current mods that prop is definatly gonna kill your RPMs.BUT you said your planning on getting a XS in the near future...That would be the prop to go with once you put your IC in..also dont forget once you ad the IC your gonna either need bigger injectors or a rising rate fuel pressure regulator or else your gonna run lean..

  5. #5
    Moderator Snoman's Avatar
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    Quote Originally Posted by Yellowsierra View Post
    Can you use the riva adjustable nossle to control the rpms as well? What size is the stock nossle on the rxp's? I know the Riva nossle kit comes with 83mm, 82mm and 81mm rings. Im guessing you lose around 100 rpms with the 1mm smaller ring.

    Justin
    To answer this question "Yes" you can use the adjustable rings to help control RPMs..The bigger the ring will raise your RPMs .The smaller ring will drop your RPMS..And yes again 1mm usually under most circumstances is equivilant to 100 rpm..The stock nozzle is 83mm on your machine..

  6. #6
    Yellowsierra's Avatar
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    Quote Originally Posted by Snoman View Post
    To answer this question "Yes" you can use the adjustable rings to help control RPMs..The bigger the ring will raise your RPMs .The smaller ring will drop your RPMS..And yes again 1mm usually under most circumstances is equivilant to 100 rpm..The stock nozzle is 83mm on your machine..

    Thanks! That helps alot. Im sure im going to atleast need a impeller in a week or so. I think im going to try a 15-20R.

  7. #7
    Moderator Snoman's Avatar
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    Quote Originally Posted by Yellowsierra View Post
    Thanks! That helps alot. Im sure im going to atleast need a impeller in a week or so. I think im going to try a 15-20R.

  8. #8
    EH Team Water Pig's Avatar
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    Stock Prop

    I have a stock RXP-X and I would like to know if that 15-20 prop is too much for my boat. I would like a bit more accelleration for closed course racing. I have an R&D intake, a Spectre SS filter on the front air box and that's it. Your thoughts..

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