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  1. #1

    Join Date
    Jul 2005
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    RXT performance by the numbers

    Tested in various combination also test conditions varry a bit due to air temps so take the average of about 80 deg 73 deg water temps. 214 lb rider.

    Stock 64.5 MPH @ 7850 RPM 7.5 lbs boost
    Vented Hood and 4Ē duck to front and exhaust mod 66.4 MPH @ 8000 RPM 8.0 lbs boost
    RR intercooler 67.8 MPH @ 8100 RPM on limiter 8 boost
    2 degree wedge 68.6-69 MPH @ 8100 RPM on limiter 8 boost
    2 degree wedge & Riva grate 68 MPH @ 8100 RPM on limiter 8 boost
    RR ECU 71.4 MPH @ 8300 RPM 8 boost
    2 deg wedge Stock grate 72.4 MPH @ 8300 RPM 8 boost
    RR cam 72.8 MPH @ 8400 RPM 8.5 boost
    New clutch and shaved SC housing 73.2 MPH @ 8450 RPM 9 boost on limiter
    Solas 14/19 74.2 MPH @ 8400 RPM 9 boost
    Stock Intake grate knifed to .120Ē new wear ring 74.7 MPH @ 8450 RPM 9 boost maybe touching the limiter

    Test the Nozzle in several positions and no positive results it likes the 2-degree wedge and stock grate for best speed and hook up, different than my hook removed RXP, which disliked the wedge and Riva grate made little difference.
    Also test 14/19 Solas at 8100 and was 69.5 MPH

    Donít think Iím going to see 75 with out headwork and pitching the prop or a 140Lb rider. Interesting that fuel level has little effect on speed and best speed numbers are ridding the very back of seat laying down head and shoulders out of the wind and almost porposing. If I test sitting up middle of seat position best speed is High 72ís


  2. #2
    Site Admin Green Hulk's Avatar
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    That's some great info Craig!

  3. #3
    Did you knife the back of the rideplate and plug the ridplate holes ?

  4. #4

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    Yes but it did not do much on this 900 lb cruiser. I think it like the back of the grate to extend down from the hull a bit and thinking about extending the front edge of the pump shoe a bit. The hook up with the stock grate is better than the Riva and I think its because of the way the stock scoops up water at the pump shoe.

  5. #5
    Phil's Avatar
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    Craig,

    Did you do any bluepriting on the hull?

    i.e:
    1. make the strakes razor sharp
    2. make the chine and transom intersection razor sharp
    3. remove rockers and hooks
    4. make the surface areas smooth (use 600 paper to create air bubbles)

    Phil

  6. #6

    Join Date
    Jul 2005
    Location
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    for once have a good straight hull there are no hooks in RXT hull like RXP. The engine seems stronger than my RXP for unknown reasons. Also it should not be spinning a 14/19 Solas to limiter but it does I think some of it is also is due to the same supercharger and clutch I used in my RXP. I'm using the same impellar I used in my RXP and spins same RPM even with the added weight, my RXP would run high 77's.

  7. #7
    I heard 1000 was better than 600 and you need to sand it front front to back.

    What are strakes ? Are they the bumps toward the front of the hull? I've wondered if knife edging them would do anything. What is a rocker ?

  8. #8
    818RXP's Avatar
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    Strakes are the front to back "rails" on the bottom. They are what the boat effectively rides on. They are hard to miss and if you can imagine, the flat part is actually what lifts the boat up. The sharper the edge, the less water drag there is......

  9. #9
    Quote Originally Posted by Burnwater
    for once have a good straight hull there are no hooks in RXT hull like RXP. The engine seems stronger than my RXP for unknown reasons. Also it should not be spinning a 14/19 Solas to limiter but it does I think some of it is also is due to the same supercharger and clutch I used in my RXP. I'm using the same impellar I used in my RXP and spins same RPM even with the added weight, my RXP would run high 77's.
    So you got rid of the hooks in the back as well as the rideplate ?

    What does this cause you to do anyway , go faster and the nose ride lower ?

  10. #10
    Quote Originally Posted by 818RXP
    Strakes are the front to back "rails" on the bottom. They are what the boat effectively rides on. They are hard to miss and if you can imagine, the flat part is actually what lifts the boat up. The sharper the edge, the less water drag there is......
    So did you add MarineTex and sand it out with 600 to make it sharp ?

    Is this a rocker that you got rid of ?
    rocker line
    the curved line lying on the plane of the centre line of the boat, on the outside surface of the hull (the keel line)

    rocker
    the curvature of the rocker line

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