Pump Cavitation
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Pump Cavitation

  1. #1
    Strap on the JATO konajet74's Avatar
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    Default Pump Cavitation

    Hi guys, My engine builder told me pumps start cavitating around
    5400-5500rpm's , so I kept the AA impeller. My motor turns it to
    5200. I'm wondering how much I'm leaving on the table?? What do
    you guys do to keep 'em loaded at high rpm's? Is this a loader
    thing? The motor's a 454 w/ 990's, roller setup approx 500-550hp.
    Just looking for the next mods........

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  3. #2
    mo balls than $cents$ IMPATIENT 1's Avatar
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    cut it down to a ab cut and get a inducer, you're not even letting that roller cam get on peak i'd bet. that or add nitrous

    Dare to be different, if it turns out great you can claim you planned it that way.

    Jetboatperformance.com

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    Strap on the JATO konajet74's Avatar
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    Man, you're on it this morning!! Thanks!! So, Inducers are the
    ticket, so I've seen from searching? That also seems like a cheaper
    route.......

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    ATTA BOY 460's Avatar
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    You could always reverse your avatar and that might help you out sum.

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    Senior Member hotbo's Avatar
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    Quote Originally Posted by konajet74 View Post
    Hi guys, My engine builder told me pumps start cavitating around
    5400-5500rpm's , so I kept the AA impeller. My motor turns it to
    5200. I'm wondering how much I'm leaving on the table?? What do
    you guys do to keep 'em loaded at high rpm's? Is this a loader
    thing? The motor's a 454 w/ 990's, roller setup approx 500-550hp.
    Just looking for the next mods........
    imo a inducer is not really the problem solver!

    does it do it on take off?if so who built the pump and what are the clearances?
    what kinda loader do you have?
    what is the pump?

    have you looked at the intake set-up in the boat?

    there is alot of different variables that can cause this without throwing money down the tubes for expensive parts that are a band-aid.inducers have there place imo just not with 500-550 hp.what i mean by this is if you build a pump right they will take off and perform just fine with those kinda hp#s.

    i would have a b-cut impeller in the boat and address the cavitation issue.
    good luck.travis

  8. #6
    Senior Member jetboatperformance's Avatar
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    "pumps start cavitating around 5400..."
    With all due respect to the Engine builder thats a fairly broad statement sort of curious what he meant Tom

  9. #7
    ... Some Kind Of Monster's Avatar
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    There are a LOT of guys spinning a lot more than 5400 RPM with no problems.

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    Senior Member Widetrack's Avatar
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    Blowing a hole in the water is a b%#$h! I am working with my pump builder right now to solve this problem! I will be running est.700 HP and we will michine the shaft for an inducer but,not install until we see if it is going to suck air! Sometimes some of the smallest things can cause cavitation and can be hard to solve! IMO! WT


    SOMEONE SAID YOU CAN'T TAKE IT WITH YOU! SO,IM BURNING IT UP ONE GALLON AT A TIME!
    WT

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    Quote Originally Posted by konajet74 View Post
    Hi guys, My engine builder told me pumps start cavitating around
    5400-5500rpm's , so I kept the AA impeller. My motor turns it to
    5200. I'm wondering how much I'm leaving on the table?? What do
    you guys do to keep 'em loaded at high rpm's? Is this a loader
    thing? The motor's a 454 w/ 990's, roller setup approx 500-550hp.
    Just looking for the next mods........
    I know a guy who spins a aluminum B impellor all the time to 7200 RPM for 3 seasons and the pump does not cavitate.

    Things the guys who know (not me) are going to need is info like:
    What hull is it?
    How heavy is the hull?
    Does it have a shoe and ride plate?
    What loader is in it?
    What jet drive is in the boat?
    Engine size, compression ratio, cam specs, dyno sheets?
    What's the boats top speed?
    AND

    Pictures

  12. #10
    Senior Member H20MOFO's Avatar
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    Default ????

    Pardon my bumbassness here, but cavitating at 5400 r's? Wouldn't one call that a loading issue instead? Possible cured with some hardware adjustments? (shoe, loader ect???) Killer avatar BTW.LOL
    Another Hot Boat refugee

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    E-7 Sheepdog (ret) SmokinLowriderSS's Avatar
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    Quote Originally Posted by jetboatperformance View Post
    "pumps start cavitating around 5400..."
    With all due respect to the Engine builder thats a fairly broad statement sort of curious what he meant Tom
    Yes indeed it is.

    I am running just shy of 6-grand WFO and not cavitating.

    There MUST be smooth water entry (not too much stuff in the way), enough intake pressure, and even accross the face of the impeller, top to bottom (the job of the top-loader), no damge to the leading edges of the impeller blades.

    "Cavitation" in an induced air bubble, caused by a drop in pressure on the water, somewhere, for some reason, a burr on an edge, a nick, water hates going uphill, so without a loader, pressure at the top of the impeller falls as speed increases, while rising at the bottom, eventually reaching a point of cavitation at the top of the impeller, air leakage at the cleanout or shaft seals.
    "As democracy is perfected, the office of president represents, more and more closely, the inner soul of the people. On some great and glorious day the plain folks of the land will reach their heart's desire at last and the White House will be adorned by a downright moron."
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    Senior Member GT Jets's Avatar
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    I don't know bout anyone else, but have seen many jets run over 6K through a jetpump, many without issue, the cavitation issue starts if the hull is heavy or not efficient...

    Just another opinion though, a properly tuned shoe and loader make a buttload of difference..

    GT
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

  15. #13
    Senior Member jetboatperformance's Avatar
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    Ergo my earlier questions? Tom

  16. #14
    Strap on the JATO konajet74's Avatar
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    Here we go..... I have absolutely NO issues right now, no
    cavitating, nothing. It jumps right the hell out of the water
    w/ no hickup. The bottom has been worked & there is no hook.
    I have a JC-A w/ stock intake grate & a diverter. I did this
    purposely to start from scratch & learn as I go. The engine is
    a LS-6 w/ 9.5:1, the heads have been mildly worked (990's).
    The cam is a Crane ZHR-288 w/ 226/234 duration @.050 &
    587/610 int/exh lift & pro hyd roller lifters. It runs awesome, I
    just think it wants to stretch it's legs some more.

    I do think it's a little heavy in the ass though! I have 2 15 gal
    saddle tanks & a heavy ass iron motor. I'm not sure how heavy the
    hull is, it's a full stringer Kona (tahiti splash)? Oh, it does around 75
    right now w/ full tanks & 3 people.

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