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  1. #1

    Where have my rpms gone?

    Some quick background.
    Old ski 2009 FX sho. Mods Vipec et 16 pound wheel. Watson cooler, riva air intake riva exhaust. R&D intake grate.13/26 skat Stock ride plate and sponsons.
    Results 8750 rpm 16.2 pounds and 81 Mph.

    Changed to Fzr as every body said the hull would be quicker. Build over Vipec wheel and intercooler. rear exit exhaust. 13/26 skat added anti cave cone R&D, riva grate and R&D rideplate and riva sponsons.So the hp bits are the same.
    Results. 8450 rpm 15.1 pounds and 81.9 Mph

    So with the same hp bits I am pulling 300rpm less with the same prop. What happened to my rpms. I added a bit of timing to the map other wise I would have been 350 rpm down.

    THANKS TO GOLD COAST WAVE RUNNERS FOR THE HELP AND THE SKI


  2. #2
    fx160's Avatar
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    the cone looks like the obvious answer you will need to repitch to get your revs back

    kev

  3. #3
    fx160's Avatar
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    are the conditions the same as when you first tested it is summer now (tomorrow)and you will loose some revs due to the heat

  4. #4
    Mate it is just the R&D cone not the TBM one I dont know if that robs rpms(300). Conditions was not perfect but intake temps were similar.
    Buddie what sponsons have you got?

  5. #5
    fx160's Avatar
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    i am still running stock sponsons
    what ever the problem is ,it looks like a repitch will fix it as you are already at a higher speed with 300 revs less
    and then there is a vx plate to add into the mix

  6. #6
    RichieFZR's Avatar
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    Better not be peeping on my motor!!! LoL

    I would change the prop to a 13/25 as what I run on mine. Jordan tried a 13/26 in mine and it went slower. Slower by how much , I don't know. As the goal is speed the 13/25 went back inn. Ride plate made need more ADJ also. Jordan spent abit of time getting the ride plate dialed on mine with the increase of HP with the mods.

    My 2cents.

    Also your RPMs maybe gone , but where have you been mate? Haven't seen you on the ride days lately.

  7. #7
    Ride it! GPR Ed's Avatar
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    I'm curious how you like the FZ hull compared to the FX? Also no FPR for the 16psi wheel? Good luck

  8. #8
    THE PLATE MAN JIM'S PERFORMANCE's Avatar
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    Quote Originally Posted by miker1 View Post
    Some quick background.
    Old ski 2009 FX sho. Mods Vipec et 16 pound wheel. Watson cooler, riva air intake riva exhaust. R&D intake grate.13/26 skat Stock ride plate and sponsons.
    Results 8750 rpm 16.2 pounds and 81 Mph.

    Changed to Fzr as every body said the hull would be quicker. Build over Vipec wheel and intercooler. rear exit exhaust. 13/26 skat added anti cave cone R&D, riva grate and R&D rideplate and riva sponsons.So the hp bits are the same.
    Results. 8450 rpm 15.1 pounds and 81.9 Mph

    So with the same hp bits I am pulling 300rpm less with the same prop. What happened to my rpms. I added a bit of timing to the map other wise I would have been 350 rpm down.

    THANKS TO GOLD COAST WAVE RUNNERS FOR THE HELP AND THE SKI
    Tunnel on SHO is smaller will let it spin more does not put as much of a load, Tunnel on FZ is bigger puts more load on engine rpm's will be down. When i mod a SHO or a FZR with the same parts the SHO always turns more rpm than the FZR or S depitch your impeller and you will be fine.

  9. #9
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by JIM'S PERFORMANCE View Post
    Tunnel on SHO is smaller will let it spin more does not put as much of a load, Tunnel on FZ is bigger puts more load on engine rpm's will be down. When i mod a SHO or a FZR with the same parts the SHO always turns more rpm than the FZR or S depitch your impeller and you will be fine.
    Jim's exactly right. Depitch that trailing edge of your impeller to get those RPM's up and your ski will pick up some more speed.

  10. #10
    Thanks for the replies. I was hoping it was the differences in the pump tunnels but was not sure.

    As for comparing the 2 hulls I loved my FX. To me it felt much better at slow speeds. The turning is more predictable. The FZ is better in chop though. I have ridden a FZ with a worx plate and that steers awesome but I dont want the loss in top speed. So I think a Fx compared to a FZ with anything other than a Worx plate the FX turns nicer.

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