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  1. #1

    Slower top end with new impeller

    Hello....I have a 2003 gtx 4-tec supercharged with 140 hrs on it. We bought it used last year.....anyway, we were having cavitation issues with it, so we had the sc rebuilt with the washer kit since it had never been done and also installed new wear ring....still cavitating....so then I bought a riva intake grate....still cavatating a bit but better.
    The only thing left was to replace the stock impeller with a 12/20 solas; that was done yesterday.....the stock impeller had a few nicks out of it, but looked not bad overall.

    The cavitation issue is much better, almost none at all, but my top speed is down from 58 mph to 52 mph.....just wondering what is the stock impeller pitch is....did I purchase the wrong impeller? You would think replacing everything mentioned would increase speed. From what I've read, this machine should be in the 65 mph range??

    Thanks


  2. #2
    mikelytle1077's Avatar
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    Quote Originally Posted by hughjordan View Post
    Hello....I have a 2003 gtx 4-tec supercharged with 140 hrs on it. We bought it used last year.....anyway, we were having cavitation issues with it, so we had the sc rebuilt with the washer kit since it had never been done and also installed new wear ring....still cavitating....so then I bought a riva intake grate....still cavatating a bit but better.
    The only thing left was to replace the stock impeller with a 12/20 solas; that was done yesterday.....the stock impeller had a few nicks out of it, but looked not bad overall.

    The cavitation issue is much better, almost none at all, but my top speed is down from 58 mph to 52 mph.....just wondering what is the stock impeller pitch is....did I purchase the wrong impeller? You would think replacing everything mentioned would increase speed. From what I've read, this machine should be in the 65 mph range??

    Thanks
    stock speed should be around 62-63 max. u need to switch to a aluminum pump if you havent yet. in stock form the 12-20 is way to much prop for the gtx i went thru the same problems. when i put my solas in i could barely pull 7200rpms so you either need more power or de pitch the prop to around a 12-17 this should get you to 7600rpms the rev limiter is set at 7650rpms. that plastic pump has to go its no good.

  3. #3
    Fastest in my cove sfackett0's Avatar
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    need to have the bellows and carbon seal replaced, and switching to a metal pump over the crap plastic one is a good idea, I just seen one on ebay yesterday, at the time is was going fora good price.

  4. #4

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    stock pitch is 13-23..my gtx with opas block off hits 65mph
    riva stage 1 kit sales 13-20 impeller

  5. #5
    Thanks for the replies....I'm 1/2 way there now with the riva stage 1 since doing the impeller, OPAS block-off kit, and intake grate. Do you think doing the remaining kit with the pump wedge and filter kit will bring this machine to where it should be, or should I also include a new metal pump?

  6. #6
    Fastest in my cove sfackett0's Avatar
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    wedge and rod are a personal choice, some like it some dont, I personally did not like the way the ski handled with it and after one season I sold mine. But if you can get a metal pump for a good price buy it, the plastic ones just dont hold up over time or constant tinkering with.

  7. #7

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    You are on the right track. That ski casn be made to haul ass with just a few mods. I have been tinkering with my wife's 2006 GTX for several years now and it has yet to be out run by any STOCK ski. Biggest improvement came when I installed the Riva rear air kit for an RXP on it. Good luck.

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