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  1. #1

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    Mods & Speeds on 08-11 RXPX machines.

    Lookin for as much feed back as possible. What Id really like to see how fast everyones been wit a STOCK X Charger and STOCK Intercooler. Im currently doin a few things to my 08 RXPX. Tryin to get some data from others. I have I/C reloaction kit, riva reduction nozzle with 82mm ring, pump wedge, 4" front air, pro series block offs, r&d intake grate, riva waterbox n rear exhaust, 15/20 repitched by speedfreeks, riva ecu and 50lb injectors. I ran the best of 79.5 mph @ 8340rpm. I had the prop pitch from b4 I had the ecu and it was running like 8180. I was pretty pleased wit the numbers but It was lean and it puked the head gasket. So now Im having the head gone threw, doin a valve train upgrade, modded ride plate by speedfreeks, torx stage 2 cam, and new bosch 52lb injectors. Im hoping to run around 82-83mph.


  2. #2

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    Looks like you have gotten a lot of speed out of that thing. I am sitting at 69.1 mph with just the r&d grate. Are you running the Athena? I guess i'm going to have to get the waterbox and ecu, then bigger sc wheel later.

    Do you have pressure reliefs yet?

  3. #3

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    Quote Originally Posted by JordanF View Post
    Looks like you have gotten a lot of speed out of that thing. I am sitting at 69.1 mph with just the r&d grate. Are you running the Athena? I guess i'm going to have to get the waterbox and ecu, then bigger sc wheel later.

    Do you have pressure reliefs yet?
    Your speeds about right for a stock ski with just a grate. What rpm are you turning? Whats an Athena? I wouldnt had a larger supercharger wheel is you have an X machine. You can go plenty fast with a stock X charger. Unless u wanna pull the blower every 30-40hrs to check slip. No I do not run a pressure relief. Not needed with the r&d grate unless I believe over 85mph.

  4. #4
    Mod less, ride more! troyheb's Avatar
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    Not sure what your prop ended up being pitched at, but IMO your speed sounds high for your RPM's. 255hp Rxpx wants to stuff around 80 mph. The R&D grate is the best and has the highest threshold, but you NEED to have pump relief. An 82mm nozzle and no pump relief at your speed, if you chop the throttle your ski will want to stuff. The smallest I would go with is a 83mm nozzle. Pump stuffing is no fun. There is a ton of info on here about the 255hp Rxpx's and what is needed to be done.
    Oh, by the way. I used to have an 80+ mph 08 Rxpx, so I am not blowing smoke.

  5. #5
    Mod less, ride more! troyheb's Avatar
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    Quote Originally Posted by JordanF View Post
    Looks like you have gotten a lot of speed out of that thing. I am sitting at 69.1 mph with just the r&d grate. Are you running the Athena? I guess i'm going to have to get the waterbox and ecu, then bigger sc wheel later.

    Do you have pressure reliefs yet?
    With just an R&D grate you should be around 71-72. Did you get the closed course grate?
    The Athena does not work on 255hp 08-11 Rxpx's.

  6. #6

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    Quote Originally Posted by troyheb View Post
    Not sure what your prop ended up being pitched at, but IMO your speed sounds high for your RPM's. 255hp Rxpx wants to stuff around 80 mph. The R&D grate is the best and has the highest threshold, but you NEED to have pump relief. An 82mm nozzle and no pump relief at your speed, if you chop the throttle your ski will want to stuff. The smallest I would go with is a 83mm nozzle. Pump stuffing is no fun. There is a ton of info on here about the 255hp Rxpx's and what is needed to be done.
    Oh, by the way. I used to have an 80+ mph 08 Rxpx, so I am not blowing smoke.
    I have no reason to lie about what my mods are and how fast it went. Everyone on here also said it would buck wit a riva grate over 74mph. I ran 77 in change for 2 yrs never an issue. I dont know what erik @ speedfreeks repitched my prop to. But the ski has exactly as I said on it. Ive been doing alot of runs n testing with it. Plus erik has a bunch of customers including one being my cousin with 08-11 X machines running 80+ mph and none of them have a pressure relief and none of them buck. I belief if Im not mistake erik himself has been 85-87mph on and x boat with no overstuff issues wo a pressure relief.

  7. #7
    Mod less, ride more! troyheb's Avatar
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    You have been warned. Good luck.


  8. #8
    Bob 1tommygunner1927's Avatar
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    Quote Originally Posted by ModularJunk View Post
    Quote Originally Posted by troyheb View Post
    Not sure what your prop ended up being pitched at, but IMO your speed sounds high for your RPM's. 255hp Rxpx wants to stuff around 80 mph. The R&D grate is the best and has the highest threshold, but you NEED to have pump relief. An 82mm nozzle and no pump relief at your speed, if you chop the throttle your ski will want to stuff. The smallest I would go with is a 83mm nozzle. Pump stuffing is no fun. There is a ton of info on here about the 255hp Rxpx's and what is needed to be done.
    Oh, by the way. I used to have an 80+ mph 08 Rxpx, so I am not blowing smoke.
    I have no reason to lie about what my mods are and how fast it went. Everyone on here also said it would buck wit a riva grate over 74mph. I ran 77 in change for 2 yrs never an issue. I dont know what erik @ speedfreeks repitched my prop to. But the ski has exactly as I said on it. Ive been doing alot of runs n testing with it. Plus erik has a bunch of customers including one being my cousin with 08-11 X machines running 80+ mph and none of them have a pressure relief and none of them buck. I belief if Im not mistake erik himself has been 85-87mph on and x boat with no overstuff issues wo a pressure relief.
    .

    Erik usually writes the pitch of the impeller inside the hub.

  9. #9

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    Im sure he does. I have my pump off but my props still in the pump for now. Erik lives about 20min from me. He wanted me to bring him the prop for a repitch for about a year already. Now that Im redoin alot of stuff I was by his house sunday morning. He wants me to leave the pitch alone till we run the ski once its fixed n see where the rpm is.

    No one runs an X-charger anymore and a RXPX? Seems like everyone these days just puts a wheel or larger blower on? What fun is that? Goin faster with less is more fun n rewarding no??

  10. #10
    rxpredviper's Avatar
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    Quote Originally Posted by ModularJunk View Post
    Lookin for as much feed back as possible. What Id really like to see how fast everyones been wit a STOCK X Charger and STOCK Intercooler. Im currently doin a few things to my 08 RXPX. Tryin to get some data from others. I have I/C reloaction kit, riva reduction nozzle with 82mm ring, pump wedge, 4" front air, pro series block offs, r&d intake grate, riva waterbox n rear exhaust, 15/20 repitched by speedfreeks, riva ecu and 50lb injectors. I ran the best of 79.5 mph @ 8340rpm. I had the prop pitch from b4 I had the ecu and it was running like 8180. I was pretty pleased wit the numbers but It was lean and it puked the head gasket. So now Im having the head gone threw, doin a valve train upgrade, modded ride plate by speedfreeks, torx stage 2 cam, and new bosch 52lb injectors. Im hoping to run around 82-83mph.
    what is you lake water temp?
    wow nice speed man @ 8380.. at 8600 you will be 83mph ...one in a million

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