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  1. #1

    I want better high altitude performance

    I own an 06 rxp with about 13 hours on it. I ride in elevations ranging from 5000 to 6500 feet and I'm looking for opinions on how to get some performance back. My rpms range around 7300-7500, and my speed is in the 60-62 mph range.
    I guess the most obvious approach would be to change the impeller, does anyone have any experience with what would be the best size and pitch to change to for this elevation?
    Also, I guess there is a way to get the super charger to spin faster with a different "wheel". What is this and what is involved in installing it?
    Which approach is better?
    Thanks for any help, Brian


  2. #2
    Quote Originally Posted by Laundryboy View Post
    I own an 06 rxp with about 13 hours on it. I ride in elevations ranging from 5000 to 6500 feet and I'm looking for opinions on how to get some performance back. My rpms range around 7300-7500, and my speed is in the 60-62 mph range.
    I guess the most obvious approach would be to change the impeller, does anyone have any experience with what would be the best size and pitch to change to for this elevation?
    Also, I guess there is a way to get the super charger to spin faster with a different "wheel". What is this and what is involved in installing it?
    Which approach is better?
    Thanks for any help, Brian
    I think going into the supercharger more would help you out for sure. I think supercharging is what allowed airplanes during WW2 to reach higher altitudes and still maintain a descent level of performance.

    However, if you do start upgrading the SC other things will need to follow such as a better SC intake and repitching your prop. I'm not sure what your process will be, but I know there are other RXP owners on here running in your elevation range. Good luck!

  3. #3
    Resident Jicky Jack Jeff C's Avatar
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    You need more boost as your current SC wheel is not compressing the thin air as much as the same wheel at a lower altitude.

    I think the stock set up is putting out around 6-8 PSI, and alot of the aftermarket wheels put out around 10-15 PSI

    I would also get rid of the stock air intake and go with a 4"

    Those two combines should get your RPM's perty near 8000 and your speed up another 5 mph.

    Also I would think you would not have to go with bigger injectors either, as the net air flow should be somewhere around stock after the changes, but you would want to run that by Jerry or others on here with more knowledge on SC wheels.

  4. #4
    vidbuster's Avatar
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    Because of this same problem, I ended up getting a Stage I upgrade. Although, I haven't tested it out yet in Lake Tahoe (6260 ft), which is usually where I keep the RXP for the summer. Before I did the upgrade, I noticed about a 3 mph loss.

    Here is a thread about it:

    http://www.greenhulk.net/forums/showthread.php?t=21295

    Good Luck

  5. #5
    JFizzleJR's Avatar
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    Like the others said; what you need is a higher performance supercharger, an external intercooler, and a fresh air intake (preferably riva rear air with flow rites to vent the air).

  6. #6
    Site Admin Green Hulk's Avatar
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    More boost is going to be the cure for your high elevation.

    At your elevation i would be tempted to run the Riva pro series supercharger (stage 3) with stock injectors and then feed it a ton of air with the Riva pro series air intake for RXP (rear air intake)
    The only reason i recommend to run the stock injectors is because of your extreme elevation. Anyone else should run 42# injectors with the stock ECU.

    I would then get a solas 14/19R and then tweak it for max RPM's (8100)
    If you need help with pitching the impeller let me know.

    Thanks!

  7. #7
    Thanks for the advice! It sounds like I have a few choices. The cheapest route would be to repitch the impeller, the moderately priced route would be to go with the repitch and get a rear air intake, and the most expensive would be the supercharger, the prop and the rear intake. I'm sure this would have the best results also.
    What about the "green" after market supercharger impeller as opposed to the Riva stage three? Or some other after market impeller?
    I bought the RXP new about 14 months ago and don't use it very much. All last summer I thought about doing something to get some speed back. Now that it's finally warmed up in Montana I want to fix this!
    Thanks, Brian

  8. #8
    JFizzleJR's Avatar
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    The Rude S/C is the best. The Green Charger is looking like the best 'bang for the buck.' Don't forget to add an intercooler to your list if you go the expensive route.

  9. #9
    JD 1's Avatar
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    Seadoo use to have high alt. ski's that they would sell in high altitude area's. but that was back in the 2stroke days.............
    Id up the engines compression, just my 2 cents

  10. #10
    JFizzleJR's Avatar
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    what about the new Les 'b' kit? Any news on that as far as being the best performer?

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