JetBoatPerformance Tom
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JetBoatPerformance Tom

  1. #1
    LP-25.com Infomaniac's Avatar
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    Default JetBoatPerformance Tom

    Tom

    I've built many decently fast boats in my boating life, stern drive v-drive but not a jet. I recognize that a "combination" must work well together. The hull engine and drive.

    So what is the best thing to do regarding the jet pump? I know that this is a wide open question but what little things can be done and what big things can be done?

    Lets say a small tunnel boat with an honest 900 HP factory stock Berk 12JG pump.

    The main objective would be? Pump the absolute most water through the thing?

    My gut tells me to install a 9 1/2 impeller, good wear ring, AT bowl a snoot etc. Bolting all of that up will not be enough. What are the basic clearances that need to be held?

    And ... what are the optimum intake pressures and outlet pressures? To tune the loader and nozzles?

    Those being the big things. What if the stock 12JG pump and stainless B were kept, what would be the little things?

    Thanks man

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    Senior Member jetboatperformance's Avatar
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    Need more info , Info wheres this motor gonna make power and hows it make it ? how big's the motor ,how small is "small" tunnel (16' 18' ?) and what boat ? Stock intake? Thanks Tom

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    Senior Member jetboatperformance's Avatar
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    Ron , alot depends on the "budget" but the "hypothetical pump deal" here could be your Berk Suction ,Meirsch cleanout cover,A/T oversize clean-out retainer bolts ,a 17-4 pump shaft, new HPstyle bearing ,Dominator bowl ,extruded honed (A/T Berk replacement bowls rated for under 500hp),Impeller choices are huge but ... AA High Helix 902 HP =5600rpm = or- ... B High Helix @914HP is 6400 rpm +or- Ride plate shoe and "appropriate" loader , depending on the hull , A/T droop, Place HPH droop or HTP straight snoot and a Place Diverter with our "Butt" bucket conversion . It will also need a solid pump kit (we use A/T) with Bronze shouldered WR .025 skirt radial, .030 frt side or Duanes Ultimate WR (been hearing a lot of good about it). Drilled and tapped for pressure readings , take it run it and "tune" from there (shoe ,intake opening, loader, nozzle opening etc) Tom

    options , Pop off / Jetaway

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    Jackwagon Patrolman Rexone's Avatar
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    Quote Originally Posted by jetboatperformance View Post
    Dick , alot depends on
    He called you a Dick.

    Right on Tom.

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    Quote Originally Posted by Rexone View Post
    He called you a Dick.

    Right on Tom.
    God don't start that spray and de-nuter with Jet Boaters. O I am Sorry, you said Dog's, so you must mean Propers.LOL and Tony the GURU, your's are too big anyway, I have seen you drive.

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    Senior Member jetboatperformance's Avatar
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    Quote Originally Posted by Rexone View Post
    He called you a Dick.

    Right on Tom.

    My Bad , fixed it sorry Ron

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    Resident Ford Nut Sleeper CP's Avatar
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    Quote Originally Posted by jetboatperformance View Post
    ... AA High Helix 902 HP =5600rpm = or- ... B High Helix @914HP is 6400 rpm +or-
    Is that the 9.5 or 9.125" impeller that SOB has some bite I sure hope it translates to more thrust. Wow. I'm guessing those are observed hp #'s?

    ? 840 hp (observed) at 6,500 what cut HH ?

    Sleeper CP
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    Senior Member jetboatperformance's Avatar
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    Quote Originally Posted by Sleeper CP View Post
    Is that the 9.5 or 9.125" impeller that SOB has some bite I sure hope it translates to more thrust. Wow. I'm guessing those are observed hp #'s?

    ? 840 hp (observed) at 6,500 what cut HH ?

    Sleeper CP
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    Jon they are actual dyno numbers that are "obseved" by an Impeller Dyno and are corrected by about 3% (net absorbsion = x .970 )

    Your 840 @ 6500 should be B to B-

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    This went off the first page?

    Been covered up Tom I'll get my reply together as soon as I can.

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    3rd page now. lol I had not intended to wait this long for my reply.

    Thanks Tom for the reply and calling me a Dick

    Naturally you would lean toward safe when making a recommendation. I'm sure there are plenty of folks that have some HP without the good shaft and the good bowl good clean out with big bolts. But you can't hardly recommend that.

    I already learned from this thread that the high helix impeller is the latest greatest. Thinking that the 9 1/2 was the deal. Is there a HP chart for that handy? My engine will make more than 950 HP.

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    Senior Member jetboatperformance's Avatar
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    Ron I have the "Dyno" numbers for all the testing including the HH , but have been waiting for permission to release them Tom

    regarding strength and safety eg performance bowl and shafts etc , theres lots of lake boats out there now running 90's to "triples" ,cant be to carefull ,as witness this is the jet for my "kid" ,high strength bowl (double drilled)17.4 shaft , stainless HH etc

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    Senior Member H20MOFO's Avatar
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    Hmmmmm, them hh #'s sure would be nice
    Another Hot Boat refugee

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    Senior Member jetboatperformance's Avatar
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    Kreg Theres pages of docs on all Imps , For now , pm me the HP and where its made I'll send you the numbers individually Tom

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    Dick,would you be building this engine or is it an engine your buddy built in his garage?

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