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  1. #1
    JSR Brad Clarke's Avatar
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    RXP-X 'Inversion' Jet Unit

    Has anyone heard of this? I have a RXP-X with a 04 RXP motor and electrics, Stage 3 Kitted + a few extras, it goes very well 80mph + in the RXP hull, it is setup for C/C racing. I just purchased a RXP-X as they handle better and with the new larger intake shoe hookup and accelerate better. I was doing a radar run last night and it was pulling upto high 70's when in the blink of a eye the ski lifted the rear and nose dived with out warning - I was over the bars at 70+ not knowing what the hell just happened, I hit the water so hard that I have two black eyes (with helmelt on) and a pretty tweaked left shoulder. I thought it might have broken an Intake grate or some thing like this but the hull is unmarked and the grate is intact. After taking to a couple of people - the idea is 'Inversion' where the pump/Intake shoe is getting to much water forced in at speed (made worse by the larger opening) and water spills back out forcing the rear of the craft to rise, therefore the nasty nose dive.

    Thoughts anyone?


  2. #2
    thesepaperwings's Avatar
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    I'm crossing my fingers this isn't the case or the pump will need work to reach higher speeds. Good to hear that your ok and that you had a helmet on. Stay safe

  3. #3
    Moderator Franko's Avatar
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    We call that over stuffing the pump. When too much water is stuffed into the pump and the pump can't handle it all, the extra water has to go somewhere. It goes in the opposite direction as the rest of the water. The effect is like pulling the emergency brake. Its the same as riding along and pulling the reverse lever. The nose goes down, the ass bucks and you go flying. Glad you are okay.

  4. #4
    REID2168's Avatar
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    did the ski do this completely STOCK or after some mods?

  5. #5
    Site Admin Green Hulk's Avatar
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    It's called pump overstuff!

    The intake opening is so large on the RXP-X that at high speed you are trying to force more water into the pump than it can process. This causes the back end to buck pitching you off of your ski. This happens between 76 and 78 mph on the X models.

    To prevent this you will have to come up with a custom grate that partially closes off some of the intake opening. In doing this kiss your unbelievable hole shot and midrange acceleration goodbye.

  6. #6
    JSR Brad Clarke's Avatar
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    Thanks for the good replys, I will start work on the grate !!!

  7. #7
    MPower's Avatar
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    Were you using the stock unmodified RXP-X grate? Also, what prop and pitch did you have?

    Glad you're okay!

  8. #8
    JD 1's Avatar
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    Quote Originally Posted by REID2168 View Post
    did the ski do this completely STOCK or after some mods?

  9. #9
    JSR Brad Clarke's Avatar
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    RXP-X Grate - but outside wings cut off and middle wing cutdown. Skat 15-19 pitched up

  10. #10
    ctriverguy's Avatar
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    Quote Originally Posted by REID2168 View Post
    did the ski do this completely STOCK or after some mods?

    Just an opinion here, but if he is doing high 70's like he said, there is no way he is stock... still does raise an eyebrow...

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