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  1. #1

    Getting an 08 RXTX to 80MPH?

    Hi, I have a 2008 Seadoo RXT-X that Iím trying to get to 80+ MPH on 91 pump gas, and needs some help, and suggestions. My list of current mods are below.
    Completely reinforced pump tunnel
    Riva top loader Intake grate
    Riva reduction nozzle (83)
    Solas R-Series Concord Impeller SRX-CD-15/22RI have a new SRX-CD-15/20 on order and a new wear ring that will be installed.
    Riva 2 degree pump wedge with the vts extension rod
    Riva pro series OPAS block offs
    4inch kanaflex ran up to front air intake duct
    Riva catch can
    Riva pro series ecu 8650
    Riva 50# injectors
    Riva valve train upgrade
    Riva Rising rate fuel pressure regulator (set to 45psi at idle)
    Stock X charger
    Intake mod, (gutted spark arrestor)
    Riva pro series sponsons
    Riva through hull exhaust
    Riva intercooler relocation kit
    Riva gen 3 intercooler
    Riva blow-off valve
    Riva thermostat upgrade
    TDR non baffled water box
    MTX-L wideband digital air/fuel ratio gauge
    Boost gauge
    Torx exhaust manifold extension

    My best speed with this setup on gps was 72mph at 8600rpm.It has trouble hooking up off the line, you can hear it cavitate.Iím hoping itís just because of the prop and wear ring that are currently in it.My question is, how far can I go with upgrading the supercharger to hit my 80mph mark, and still be able to run closed loop, and on 91oct pump gas?I have a riva xxx charger for it, but Iím thinking that will be pushing it too much, since I would have to go open loop according to riva.Was thinking maybe the 68-140 Xtreme LE.What do you guys think, will this get me to my goal of 80mph, and still be able to run off 91oct pump gas?Also an issue I was having when I took the ski out was getting the correct readings on the AFR.At idle it would show 14.8 to 15.0+ would jump around.At WOT I could only get it to 12.8 to 13.2 would jump.Playing with the fuel pressure, I could not get it any lower than 12.8 at WOT.I have the base pressure at 45 and itís set up for rising rate.It goes a little over 50psi at WOT.I can hear the difference in the way the engine idles when I raise and lower the pressure, so I know itís working, can also smell when I have it running rich.Iím thinking maybe the o2 is just not down far enough in the manifold to get an accurate reading, or something.I just drilled the hole, and installed it, I did not countersink the hole like the riva instructions said.Could that be throwing off the readings?The ski seems to run great with where itís set besides a little hesitation off idle.What are your guysí thoughts and opinions?ThanksÖ


  2. #2
    Bob 1tommygunner1927's Avatar
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    First, get rid of the Riva intake grate and replace it with the R&D (non closed course) grate.

    /http://www.greenhulk.net/forumsshowthread.php?t=152291

  3. #3
    captain slow Turbo Retro's Avatar
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    maybe perhaps add some pics to this thread so see where your 02 bung is??

    you should be getting better speeds than that with all the mods you are running.

    shine a light from the intake grate area and take a pic from the rear pump area.. that gives you a rough idea how bad the wear ring is.

  4. #4
    Water4fire's Avatar
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    You will not do it with the stock X SCer. Period. I have built 3 of them and they all need a Riva Pro SCer, 137+4, 2Rude to get there.
    Also dump the Riva Delpi's they lock up at fuel pressure at about 65lbs.
    I have run Bosch 48's and 50's and both worked well with the Riva ECU.

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  6. #5
    captain slow Turbo Retro's Avatar
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    Quote Originally Posted by Water4fire View Post
    You will not do it with the stock X SCer. Period. I have built 3 of them and they all need a Riva Pro SCer, 137+4, 2Rude to get there.
    Also dump the Riva Delpi's they lock up at fuel pressure at about 65lbs.
    I have run Bosch 48's and 50's and both worked well with the Riva ECU.
    yep bosch only for injectors.. had all the others lock up when i was supercharged..

    its kinda being funny on the other side of the spectrum.. i backed OFF at 88mph a few weeks ago with my 07RXT because i was simply too scared and into self preservation.....

  7. #6
    boost junkie skidoochris's Avatar
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    add boost you will get there fast

  8. #7
    Awesome, thanks for the replies. I will definitely be ordering some bosh injectors for it then, and the r&d grate to try. I had a wox grate on it, but that one seemed to slow it down a bit, was awesome in chop though... So now if go with a 137 wheel, or a rude 2 will I be able to stay closed loop, and still run it on 91oct pump gas? Will also get a pic posted asap of the o2 install..

  9. #8
    Mod less, ride more! troyheb's Avatar
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    I would not stay closed loop if you are going for 80. They tend to want to overheat if you do long WOT runs.

  10. #9
    Mod less, ride more! troyheb's Avatar
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  11. #10
    Quote Originally Posted by troyheb View Post
    Hum, so according to that, the worx grate gives the best speed, and ride. Thanks for posting, looks like I'll keep the worx grate on it.

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