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  1. #1

    Rxp wot boost loss!

    Hey guys, Iíve got a real brain teaser for the mechanics out there and any help would be greatly appreciated!
    I have a 2013 rxpx 260 with: intake, through hull exhaust, wide band, top end, intake filter removed, catch can, rising rate fpr, 137+4 wheel, 9000k tune from race labs, 14/19 solas, bov.
    The ski seemed to be pulling hard up to 8200 and falling flat on its face, I removed the bov and it doesnít seem to be falling flat anymore, but itís not going any faster. Iím at 8200rpm at 72mph. According to my wideband Iím around 15-16lbs until I hit 8200 and then it bounces around 8psi. I donít know if thatís instrument error or what. My AFR is around 10.2-10.8 at wot. I was initially running 62lbs base with rising rate, I cranked it up to almost 70 and no change. Does anyone have any ideas? Iím completely stumped!

  2. #2
    ptscon's Avatar
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    You're way way way too rich. With that charger you should be just under 13 at 8200 and around 12.2 at full RPM which should be about 400 higher than what you're seeing.

    What timing are you running at WOT?

    Also, your boost gauge is way off, at 8200 that charger might see 13 psi.

    1. Get your AFR lower
    2. Switch to Solas 15/19 (it's a faster impeller, not just different pitch)

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  4. #3
    Ok I will dial back the regulator and lean it out.
    I don’t know what the timing is, I’ve never messed with it. And I will look into the 15/19!
    do you think running that rich could be part of my issue with the low rpm/power at wot?


  5. #4
    tiderider's Avatar
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    Set it at 55 Psi. It should run like a beast at 12 afrs at wot. I run the et137+4 with 12 afr as a wot target, typically hitting 8500-8600 Rpms with 15 PSI boost on logs.

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  7. #5
    tiderider's Avatar
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    Quote Originally Posted by Bbqb4racin View Post
    do you think running that rich could be part of my issue with the low rpm/power at wot?
    YES!!

  8. #6
    Thanks for the info guys!
    tide, what impeller do you run and at what speed?

  9. #7
    ptscon's Avatar
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    15/19 is the best impeller you can get for your setup.

    You're probably losing 200 - 300 rpm running in the 10s and probably dumping gas into the oil. Set pressure to 58 psi since most likely that's where the ski was tuned at.

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  11. #8
    Ok sounds good. I’m going to order the 15/19 from Jerry. I appreciate the input!

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