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  1. #1
    Jarrett's Avatar
    Join Date
    Apr 2005
    Waxahachie, TX

    My 06 RXP Mod Results

    Date: 7/22/2006
    Mods: Stock
    Altitude: 530
    Air temp: 100
    Water temp: 90
    Humidity: 55%
    Fuel: 6 bars
    Oil: over full
    Prop: stock
    Boost: stock
    Max RPM: 7960
    Peak Speed: 66.7

    Date: 8/6/2006
    Mods: RR ECU
    Rear air intake
    K&N/stock elbow
    Altitude: 530
    Air temp: 103
    Water temp: 93
    Humidity: 63%
    Fuel: 4 bars
    Oil: over full
    Prop: stock
    Boost: stock
    Max RPM: 8140
    Peak Speed: 69.5

    It's hard to tell how much the ECU is helping at this point. As far as the air intake, all I did was unclamp the stock elbow hose from the SC and the rest of the air intake system and rotate it about 30 degrees or so up. Then I removed the plastic chute that comes down off the engine cowling. I then attached the K&N filter (that comes with the Riva air intake) onto the stock elbow and positioned it right under the rear vent in the engine cowling.

    My very first run on this setup yielded 8200-8220 RPMs, but I didn't have the GPS on... Quickly after that the 103 degree, humid air soaked the engine down to where it fluctuated between 8120-8180 RPM.
    I think the RR ECU has too rich of a fuel map for the stock setup. I get a little bogging at idle and when I blip the throttle. I guess I need to lean it out with a little more boost.

  2. #2
    Jarrett's Avatar
    Join Date
    Apr 2005
    Waxahachie, TX
    More results from the 06 RXP. A little different than I expected. 5 MPH gain today up from the last set of mods and 8 MPH over stock.

    I gotta say thanks to Franko for working on this with me. Just so you know, Franko friggin rocks on modding RXPs now. Definitely the best dude in Texas I know of thats working on them. Also, thanks to S71BB for the assistance as well!

    Previous Mods:

    Rotax Racing Reflashed ECU
    K&N/Stock elbow/rear air intake

    Mods added this time:

    Rotax Racing IC
    Rotax Racing Exhaust Pipe
    Rotax Racing SC Impeller
    Les washers
    42lb injectors
    Riva Grate
    Riva Pro OPAS B/Os
    Riva SS Wear Ring
    GreenHulk tweaked Solas 15/20 (-2mm)
    Rideplate holes filled
    Removed nose cone

    Date: 9/4/2006
    Altitude: 530 ft.
    Air temp: 75
    Water temp: 82
    Humidity: 100% (raining)
    Fuel: 8 bars (full)
    Oil: over full
    Rider Weight: 320
    Prop: GreenHulk tweaked Solas 15/20 (-2mm)
    Boost: ? (near 10)
    Max RPM: 8380
    Peak Speed: 74.5

    Notes: Weird day. It was raining lightly all day and very foggy. Temps were down and RPMs were up, but the RPMs/speed didn't jive with this pump combo. Usually 8350 RPM on this pump setup equals 75 MPH (on lower gas). Since it’s a new ski, we sorta have to take it at face value, but the 04 RXP was showing the same signs. We guessed it was one of more of these three things that could be affecting performance: Humidity, removed nose cones, or weather blocked GPS. Jury is still out.

    On a positive note, the ski ran flawlessly the first time we took it out after mods. That's a first for us. Usually, there is something that needs tweaking after a massive mod install, but I guess Franko and I are getting better at this.

    Also, this ski is at least 2 boat lengths quicker than my similarly-equipped 04 RXP and potentially 1-1.5 MPH faster but we need to verify that with the GPS next time out. It also hooks up well in the chop, shows no signs of porpoising and corners *much* better that my 04 RXP. The 06 sponsons/Riva Pro-Series blockoff combo on this ski produced some surprising cornering results that I did not expect at all. It's one of the best turning RXPs I've ridden to date.
    Last edited by Jarrett; 11-25-2006 at 12:08 PM.

  3. #3
    Jarrett's Avatar
    Join Date
    Apr 2005
    Waxahachie, TX
    Altitude: 520
    Air temp: 68
    Water temp: 77
    Humidity: 38%
    Water: Smoove (light wind chop, ie. perfecto)
    Rider Wt: 325

    06 RXP
    Fuel: 2 bars
    Prop: Green Hulk 15/20 (-2mm)
    Boost: ?
    Max RPM: 8580
    Peak Speed: 77.1 (more throttle to go)

    The only difference here is that I removed the K&N from the stock elbow since it wouldn't stay on and the ride plate holes had been sucked out again.

    Woohoo, I love the difference cool air makes I couldn't hold the 06 RXP WOT because it would have gone into the 8600+ RPM range. I'm not sure how much it had left to go, but I didn't want to float a valve to find out. If I could prop this ski to run 8500 in this air and get Frank (+1-1.5 MPH) on it... who knows what it would hit. 78+ MPH would be easy I think.
    Last edited by Jarrett; 11-25-2006 at 12:10 PM.

  4. #4
    Jarrett's Avatar
    Join Date
    Apr 2005
    Waxahachie, TX
    Latest results as of 11/25/2006:

    Started playing with the pump setup a bit. Here are the test conditions yesterday:

    530 ft. elevation
    65-75 degree air (we tested all day, so temps were up and down)
    59 degree water
    75% humidity
    2 bars of gas

    Configs tested:

    GreenHulk 15/20 (-2mm) w/ 81mm Venturi @ 8420 RPM = 77 MPH @ 64 degree air
    Damaged stock Solas 15/20 w/ 83mm Venturi @ 8160 = 75.5 MPH @ 75 degree air
    GreenHulk 15/20 (-2mm) w/ 82mm Venturi @ 8400 = 77.1 MPH @ 70 degree air

    Then I went back out again this morning to get some cooler air:

    530 ft. elevation
    60 degree air
    59 degree water
    85% humidity
    2 bars of gas

    GreenHulk 15/20 (-2mm) w/ 82mm Venturi @ 8540 = 78.1 MPH


    The 82mm ring seemed to be the ticket for the prop I have. The 81mm choked it down a little too much it seemed and started getting the diminishing returns. The 82mm seemed to be a decent trade off of RPMs for speed.

    Another thought is that the RR ECU needs RPM to make speed. Unlike the Riva setups, the RR ECU needs to spin big numbers to get the boat moving. With that said, the valve work is an absolute must to get big numbers with this kit. I guess I need to start weighing my options on getting that done versus the urge to go faster.

    Things that could still be done to make this ski faster:

    4 inch rear air intake (running stock elbow on SC currently)
    Fill the ride plate holes
    Trim the reverse bucket
    Add a wedge
    Find a site where I can pin it for a mile
    GPS it with a lighter person on it
    GPS it at sea level

    I think doing those things could potentially squeeze out another 2+ MPH from this ski, but 78 MPH is plenty for me as it stands. As of right now, this looks like all the mods I am going to do it and I am pretty happy with the results.
    Last edited by Jarrett; 11-25-2006 at 12:04 PM.

  5. #5
    Moderator The Bandit's Avatar
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    Jul 2006
    Wilmette, IL

  6. #6
    Site Admin Green Hulk's Avatar
    Join Date
    Apr 2005
    Morgan City, LA
    Very good results!

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