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  1. #1
    bradsta's Avatar
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    rxpx problems????

    Hey guys just did some upgrades on my 2008 rxpx but something isn't adding up??
    Started out with stock ski with just a worx intake grate, re blockoffs, manifold filter removed, riva free flow exhaust and free mods, ski ran a best of 72.8mph
    Just added a 4" intake, riva xx s/c upgrade, 15/22 prop and 83mm nozzle. Took the ski out today, was flat water and the best it ran was 74mph @8120/40. Rode it back to the ramp swaped back to the stock 87mm nozzle went back out and ran 73.6 @8140/60
    So question is why was there only a difference of about 40rpm between nozzles? (was under the impression it was around 100rpm per ring??) And only a .4mph difference?
    But my main concern is shouldn't the riva xx s/c upgrade give me better speed numbers than that, i thought it would pull harder than what it does, feels only slightly better than stock and the charger has just been fully rebuilt with new clutch and seals
    Help??


  2. #2
    hero's Avatar
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    Your pretty much on the rev limiter with 87m ring and will lost top speed as the ecu pulls timing..u will gain better speed with a 82 or 81m ring an pitch your prop...temp also affect topspeed.

  3. #3
    Mod less, ride more! troyheb's Avatar
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    The Worx grate is holding you back some, but my biggest concern is what injectors are you running?

  4. #4
    Mtuned's Avatar
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    Quote Originally Posted by troyheb View Post
    The Worx grate is holding you back some, but my biggest concern is what injectors are you running?
    I didn't see injectors listed either. Or a RRFPR.. Do you have a wideband? Have you checked the afr of ski?

    Also If your that close to the limiter as stated the PX’s start pulling timing right before rev limit to keep you away from redline.

    I’m sure troy or someone more familiar with the X stuff could help!

  5. #5
    Having Fun jp1300r's Avatar
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    Once you add a bigger SCer to the ski. You need to monitor your AFs. I think you are lean, if all you did was put the XX SCer on. Tune with the 83mm nozzle, don't go smaller especially with a WORX grate. You need to make sure the prop is correct. Most all out of the box props are messed up. They need a repitch right out of the box to get good speeds and holeshot.

  6. #6
    bradsta's Avatar
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    Thanks guys for reply, jp i was given the 15/22 from a mate all the edges look good but i don't know if he had pitched it but it had been used?
    Not running a rrfpr or wideband and yes they are the stock injectors, i was told it was the same as a bkit in boost and sdc run their bkits with the stock 42's. It is getting retainers and 8650 remap this week so i can go to the seimens 60's if it is safer but was told it would be fine on the 42's???
    So what speeds should i be getting with the setup before the ecu?, and how many rpm is the limiter on a px?
    I have read (szt8b7 09 rxpx upgrades) post on his px over and over so am using that as a base line on where i should be but mine is just not adding up!!
    Cheers bradtsa

  7. #7
    Mod less, ride more! troyheb's Avatar
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    With 42's you dont have enough fuel. With you current setup I would run 48's, and possibly a rrfpr.
    Also as JP said you really need to monitor your afr's.

  8. #8
    Your on the limiter. Pitch your prop

  9. #9
    MSRXP's Avatar
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    You need an 83mm nozzle to bring the rpms down. With the xx, you are fine with 42's. However, the oem's are not what you need. A set of bosch. The xx is similar to the et 137. You need an RRFPR and an MTX-L kit from innovate to monitor your afrs. Good luck. That 15/22 will be almost perfect for that 83mm oem nozzle.

  10. #10
    bradsta's Avatar
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    Quote Originally Posted by MSRXP View Post
    You need an 83mm nozzle to bring the rpms down. With the xx, you are fine with 42's. However, the oem's are not what you need. A set of bosch. The xx is similar to the et 137. You need an RRFPR and an MTX-L kit from innovate to monitor your afrs. Good luck. That 15/22 will be almost perfect for that 83mm oem nozzle.
    Ok so would you say that the 74mph with the 83mm nozzle and 15/22 @8120/40 that the ski ran is about right with the worx grate??
    Could i ditch the rrfpr and get the ecu mapped for the seimens 60s and be the same??
    I liked the way the ski felt with the 87mm nozzle, felt a little lazy with the 83 but speed was slightly better, so repitch or where do i go now?? And what is a px limiter set at??
    cheers bradsta..

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