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drmiller100

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Berkeley impeller clearance
« on: April 28, 2013, 03:21:56 pm »
I'm building a small river boat on a small budget. I bought an old berkeley pump, took it apart, and did some measuring.

There is a TON of clearance between the impeller and stator, and I need to cut some more off the impeller for the engine i'm using.

Oh. The engine is a 3.5 liter v6 with 250 horsepower or so, 10:1 compression, fuel injected.

My goal is a TON of thrust at lower speeds.  Top speed is a maximum of 50 mph.   Basically, I am thinking I want to turn my berkeley into a "volume" pump for a lower horsepower application.

So, Question.  Does anyone ever build up the stator so the vanes are closer to the impeller?  I would think that would help hole shot, and a bit surprised I don't see any talk of it when searching.

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mash on it

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Re: Berkeley impeller clearance
« Reply #1 on: April 28, 2013, 04:09:52 pm »
A stuffer plate to take up the clearance between the impeller (rear skirt?) and bowl, on a low hp set-up probably minimal gain. wear ring to (front)skirt @ .012" per side, per berkeley, .024/.025" total. This is a pressure pump, and changing it to a prop-in-a-tube axial flow pump is a GIANT step backwards. Panther, Jacuzzi YJ, Hamilton, Scott, among others are an axial flow pump, and for there intended purpose are fine.

250 hp @ what RPM? A mild or stock 350 chev delivers 260 hp,(merc) and might turn an 'A' berk impeller 41-4200 rpm's, a 'C' impeller might net 4600 r's, definitely not 50 mph, unless its in a 12' jon boat  ??? (Thanks Tom...  http://www.jetboatperformance.biz/pages/Jetdrive_Impeller_calculator.html )

How small of boat?

How small of budget?  $1.78?... $10K?

Others here know more about the pump(s) and mod(s) for them...

Bottom line.........speed costs money, buy as much as you can afford    ;)

Dan'l
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CJ/RR 212...under construction  "Pistol Annie"

GT Jets

  • Karma: +192/-0
Re: Berkeley impeller clearance
« Reply #2 on: April 28, 2013, 04:58:30 pm »
Volume takes a much HP as pressure.

It is my humble opinion that you are thinking about it all wrong.

To get small HP to work in a riverboat, you need to start thinking nozzle velocity and not volume.

You are going tip want that pump to allow the motor to turn up to where it makes the most horse power. That being said, start thinking smaller.

Smaller impeller cut (like a BC) and smaller nozzle outlet.

GT

Sent from my SGH-T989 using SoCalJetBoats mobile app
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

drmiller100

  • Karma: +0/-0
Re: Berkeley impeller clearance
« Reply #3 on: April 28, 2013, 05:09:07 pm »
ok.
Thank you for your thoughts.  engine needs to spin to 5000 rpm. I'll build the boat, and start whittling on the impeller until it spins the right RPM.
Boat will be 16 foot or so, think metal, and should weigh in the 1200 to 1500 pound range.  Will have delta pad, 12 degree dead rise, 5 foot bottom.

I don't care if it only goes 30 mph, as long as it pops up on plane in 15 feet or less.

My buddy is the Scott distributor for the US. He is helping me a bunch, but his product is out of my price range.

He has a really cool small pump for this application, but I can't afford it. 

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drmiller100

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Re: Berkeley impeller clearance
« Reply #4 on: April 28, 2013, 05:12:48 pm »
so, lets say I get my baby engine to spin a whittled down B impeller to 4200 rpm.

If I open the nozzle up a bunch, will I get more RPM?   Maybe less top speed I understand, but more RPM? Which means I should be pumping more volume of water.

Which means I may have a better hole shot?

I am confused as to why I would want to run a small impeller AND a small nozzle.  Wouldn't I want a small impeller and big Nozzle?
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Re: Berkeley impeller clearance
« Reply #5 on: April 28, 2013, 05:20:32 pm »
so, lets say I get my baby engine to spin a whittled down B impeller to 4200 rpm.

If I open the nozzle up a bunch, will I get more RPM?   Maybe less top speed I understand, but more RPM? Which means I should be pumping more volume of water.

Which means I may have a better hole shot?

I am confused as to why I would want to run a small impeller AND a small nozzle.  Wouldn't I want a small impeller and big Nozzle?

Opened up equals less rpm. Volume is work, work takes horsepower.

Here is a relatively cheap recipe for you.

Inducer, shouldered wear ring, stuffer plate and a C or maybe a BC impeller and a Place Diverter with changeable inserts. You should be able to make it come out of the hole like it's afraid of water.

If you are making peak power at 5k,I would let it run up to about 4,600 rpm minimum.

GT

Sent from my SGH-T989 using SoCalJetBoats mobile app

  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

drmiller100

  • Karma: +0/-0
Re: Berkeley impeller clearance
« Reply #6 on: April 28, 2013, 05:30:14 pm »
Opened up equals less rpm. Volume is work, work takes horsepower.



I'm new to the berkeley pumps.  This is so counter intuitive to me, but I'm sure you are right.

It seems like bigger nozzle would be less pressure with same volume.
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GT Jets

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Re: Berkeley impeller clearance
« Reply #7 on: April 28, 2013, 05:41:07 pm »
I'm new to the berkeley pumps.  This is so counter intuitive to me, but I'm sure you are right.

It seems like bigger nozzle would be less pressure with same volume.

The Berkeley family of jets is simply a centrifugal pump.

You cannot gain one without losing the other. The volume would go up with a larger nozzle, this is true, but you are leaving it too open ended.

A standard Berkeley nozzle would be way more than adequate for volume, but it will stay loaded better if you have a decent pressure rise. This is why I am recommending a smaller (talking fractions of an inch smaller) than stock.

You wouldn't want it to cavitate too easily on the river. This I know for a fact (grew up on a Whitewater river).

Have you looked into a sport jet?

Gt



Sent from my SGH-T989 using SoCalJetBoats mobile app

  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

drmiller100

  • Karma: +0/-0
Re: Berkeley impeller clearance
« Reply #8 on: April 28, 2013, 06:55:04 pm »
sport jet has its issues also. neat setup though, but pricey.

and annoyingly loud.
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