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  1. #1
    Vern's Avatar
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    My stage 2 RXP, 75.5+mph at 7900 rpms, yahoo!

    Finally got my 2005 RXP in the water this weekend. The mods are: RR front motor mount, Riva Air Filter (stock location), Denso IXU27s, my modded water box, RR thru hull, Riva grate, Riva IC, Full Skat mod pump and SS liner, adjustable venturi with rings, Les Cooke SC washers on stock supercharger, stock ECU, 158 degree t-stat, Riva finger throttle (nice!), Rule bilge pump, oil catch can, tweaked Solas 15/20 (I pulled 2 mm out of the trailing edge). I have filled the ride plate holes, but not sanded the plate yet, do have a wedge on still too. Oh, also reinforced my pump tunnel (underside, water side) with 5/8 oz carbon fiber and two coats of West System Marine epoxy ... had one crack in the gelcoat and it pissed me off, decided to fix any potential problem there before it became an issue.

    I put the 81 mm ring in the pump and threw it in the water. After figuring out a water leak (other post), I made a few speed runs ... 75.5 - 75.9 mph on my Garmin GPS ... at 7900 - 7950 rpms! My gauges said it was 90 degree air, humid, and water temp was 72 degrees, very hot for Michigan Memorial Day ...

    Obviously I need to put in a bigger nozzle ring, but I was too busy having fun with it finally to mess with it. Anybody know how much rpm difference each .5mm change (or 1 mm change) in nozzle rings makes??

    I have rings from 81 - 83 mm in .5mm increments. I think with the right ring and a cooler day ... high 76s or low 77 mph is possible maybe ...


  2. #2
    Moderator RX951's Avatar
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    Thats awesome !

  3. #3
    Site Admin Green Hulk's Avatar
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    Good job Vern. Put the 82mm ring in and get your RPM's up to 8100. Your speeds will increase too.

  4. #4
    Vern's Avatar
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    Thanks, I was happy. I know I should have swapped rings, but it was too @#()* nice out to waste any more time wrenching!

    I did notice a little porposing on top, need to install my RE blockoffs yet.

    One thing I forgot to mention was that I also cut out all my 'sharks teeth' in the pump inlet ... made the tunnel reinforcement so much easier, and the ski runs great without them.

    Does anybody know how much speed difference 200 rpms might make? Or how much rpm difference the rings make? Jerry, I think the 82 is probably the right one, but then again, on a cooler day I will pick up a few rpm too ... it was really hot this weekend.

  5. #5
    Site Admin Green Hulk's Avatar
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    200 RPM's should get you 1.5 more mph

  6. #6
    Vern's Avatar
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    Holy cow, that would get me to 77 maybe! Nice ...

    Most of my recent mods were for reliability, not necessarily for speed, so it was nice to see the gains. Funny ... altho I switched intercoolers and opened up the waterbox, I still only register the same 7 lbs of boost on my gauge as last year. Oh well, maybe my gauge stinks ... I guess if I am running 75.5 on a stock SC, the boost must be getting into the motor. I still have my Les Cooke A kit supercharger and reflashed RR ECU sitting at home. I think I might sell those parts ... I like reliability as much as speed and my current setup should be pretty reliable.

    By the way, without this forum ... who knows where my ski would be. Thanks for leading the way Jerry, I have learned tons about the ski here.

  7. #7
    Happily Self-Employed WFO's Avatar
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    Good Job Vern !!!

  8. #8

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    Vern, those are very good speed numbers for a ski that is still using his stock ECU and SC, do what Jerry say, put that 82mm ring there and you should gain more accel and top end speed DAMN, i need to buy a RXP ASAP!!!!

    Ray

  9. #9
    Vern's Avatar
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    Thanks Rich and Ray, I was surprised and happy with the numbers. I immediately knew I was going faster than last year since it would porpose if I was not paying attention. But the speeds were higher than I thought they would be, esp with the tight nozzle. Hopefully I will have some time this weekend to flip nozzles and try again with more rpms.

  10. #10
    Been there and back! BDNJ's Avatar
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    Vern - great job. Bump those rpm's up and 77 is comin' your way.

    Can't believe you had the balls to cut the shark's teeth though! Get the RE's on and run it down. You've got more in there!

    Brendan

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