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  1. #1
    immred's Avatar
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    What should Boost Pressure Be?

    2010 RXT-X260, 4" Front Air Intake, R&D Grate, V-Tec Reflash, Manifold Flame Arrestor Removed, Solas 15/22R, Rivas Catch Can, Ride Plate Holes Filled.
    Have V-Tec rpm at 8350 but never see more that 8140. I can't find a boost leak so I installed a boost guage.
    What should boost run at idle and wide open?
    Thanks, Ed.


  2. #2
    boost junkie skidoochris's Avatar
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    idle -8 and at 8150 about 10 psi
    at about 6000 you should loose vacuum
    15/22 sounds big for a x charger

  3. #3
    Autism Speaks. Its Time To Listen gOt BoOsT's Avatar
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    boost is rpm dependent. at your rpm you should be seeing around 10~10.5psi. im seeing 11psi at 8200rpm with similar mods. vacuum should be -10in/hg at warm idle.

  4. #4
    stuckmoto's Avatar
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    Quote Originally Posted by skidoochris View Post
    15/22 sounds big for a x charger
    Yea...you should probably pitch down to 15/21 or 15/20 even. You can try it yourself but I recommend sending it to Erik!

  5. #5
    monaroman76's Avatar
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    You do not have a boost leak. You just have too much prop as others have mentioned.

  6. #6
    immred's Avatar
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    Last year when I changed props the 20/22R was the forum recommendation. I was looking for top end not hole shot. I'm not sure what "too much prop" means". It sounds like your saying the prop has too much grab and it's holding the RPMs back. It doesn't seen like any size prop would be capable of holding back 260HP. Any thoughts to help me understand would be appreciated. I'm in VA so my season willbe over in Oct. If I need to I'll have the prop re-pitched durig the off season. I hate taking the pump off. Thanks Ed.

  7. #7

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    "prop has too much grab and it's holding the RPMs back."

    Yup

  8. #8
    boost junkie skidoochris's Avatar
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    immerd does your skid have a 85 or 83 mm nozzle and what is your speed?
    is does not take much prop change to gain 200 rpms
    you dont want to be on the limiter
    and with cooler wether coming, you may gain some more rpms
    imo leave it untill next spring, not much riding left this year for most

  9. #9
    immred's Avatar
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    My nozzle is "stock". I don't know if it's 83 or 85. This weekend I'll measure it. If a change will help I'll do it.
    I've received a lot of good info here so I believe the people saying the pitch is costing me RPMs but still it's hard to imagine that a minimal pitch change can hold back a 260HP motor. Out of the hole; OK, lower RPM bigger load on the motor. Wide open moving water through the pump at over 70 MPH a minimal pitch change drags the engine down? As far as speed I'm only getting about 72 MPH. I thought having more prop would move more water with a load change the engine cold handle. If I go to less pitch won't I move less water so even if I pick up some RPMs I won't pick up any speed. I don't know, just asking.
    Thanks Ed.

  10. #10

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    Quote Originally Posted by immred View Post
    My nozzle is "stock". I don't know if it's 83 or 85. This weekend I'll measure it. If a change will help I'll do it.
    I've received a lot of good info here so I believe the people saying the pitch is costing me RPMs but still it's hard to imagine that a minimal pitch change can hold back a 260HP motor. Out of the hole; OK, lower RPM bigger load on the motor. Wide open moving water through the pump at over 70 MPH a minimal pitch change drags the engine down? As far as speed I'm only getting about 72 MPH. I thought having more prop would move more water with a load change the engine cold handle. If I go to less pitch won't I move less water so even if I pick up some RPMs I won't pick up any speed. I don't know, just asking.
    Thanks Ed.
    It's all about fine tuning.more rpm = more boost

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