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  1. #1
    Ultra250XRider's Avatar
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    Ultra Mod's vs. RXP Mod's

    Could someone help me understand something? We make modification to our Ultra’s and are very pleased to hit the 70mph mark. How are the RXP & RXP-X guys hitting 85+ mph? I know the hull is lighter, but that can’t be all. Are the 4-tec Rotex engines that much better then ours? If so, can someone please explain how and why?


  2. #2
    Quote Originally Posted by Ultra250XRider View Post
    Could someone help me understand something? We make modification to our Ultra’s and are very pleased to hit the 70mph mark. How are the RXP & RXP-X guys hitting 85+ mph? I know the hull is lighter, but that can’t be all. Are the 4-tec Rotex engines that much better then ours? If so, can someone please explain how and why?
    We used to say and still say the same thing about GPR's. And how much $$$ are we dumping into our skis to see 85+mph? And how reliable are those skis? Don't kid yourself, once the RXP's are seeing those speeds there is more going on behind the scenes than you think. 8500-9000 RPM and 15+psi of boost take a toll on the engine. Shibby talked about this not too long ago on our side.

    But to try to answer your question A LOT has to do with hull design: wetted surface, efficiency through the water, pump efficiency, etc. Have you raced a RXP in chop yet? Look where your hull excels and where our hull excels. Two totally different conditions. Take a look in the photo gallery at some of the fast GPR's. Notice hull little of the hull is in the water....then look at an RXP...then look at the U250X. There are A TON of factors. For you guys it takes a lot of HP to push the hull through the water, but where you lose advantage on smooth water you gain it in chop.

  3. #3
    Moderator Franko's Avatar
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    In addition to what RXP Rex said, the after market for the RXP is far more advanced than the after market for the U250. This is mainly because the RXP has been on the market since 2004. In a few years, the U250 will have more mod options and hence more speed.

  4. #4
    JET250's Avatar
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    +1 rxp-rex, my friend has spent 10K I have spent 1.5k, he leaves me for dead from a standing start, but in the chop he can't even stay on his. its just like a dirt bike and a road bike...horses for courses.

  5. #5
    I agree, we are just around the 70's while the seadoo's have reached 90+.

    One thing to keep in mind however is that the ultra's hull desighn is more for stability and offshore handling. In chop or rough water the ultra will lose very little in topspeed compared to the loss the seadoos will suffer, that is where the v-hull desighn shines.

  6. #6
    I'm very interested to hear who is getting 80 mph out of a RXT (or RXTX) and keeping it reliable. What is there setup? Is the 80 mph speed and relative reliability even possible? I define reliable as at least 25 hours of fairly hard running with no problems.

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