SoCal Jet Boats
Tech Talk => Jet Pumps => Topic started by: mstrader77 on February 03, 2014, 07:06:37 PM
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The loader that came off my pump is pitted and I don't trust it. It looks like a Sport Edition loader. I was going to install the rock grate off of another pump I have, but it appears too short. The rock grate came off an H-2518 intake. This intake is longer than the H-2155, but the grate bolts closer towards the impeller making the grate short. This leaves about a 2 inch gap behind the grate when bolted in the H-2155 intake.
Here are my questions:
1. How long is the stock rock grate for a JC pump with an H-2155 intake?
2. I notice Berkeley has a 7 and 9 bar grate on their website, but all the used grates I see are 6 bars (including mine). What are the advantages/disadvantages of the different styles?
3. I have read that loaders improve top speed, but can cavitate out of the hole. Is this true of a sport loader?
Thanks for the help.
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I can tell you that a loader made a world of difference to my launch and helped all around, especially in the chop.
It is true that the older blocker styles do cause cavitation out of the hole and actually all around. Blocker loaders work by depriving the impeller of water and inducing cavitation. The blocker design closes off the opening in the center of the intake. Because the blocker loader is partially blocking the intake opening, water is deflected out of the pump. This deflection has some benefits: 1.) it generates more lift in the rear of the boat to reduce drag, 2.) it allows the engine to RPM up into its power band with a pump that has an impeller that is too large. Depriving the impeller of water causes pseudo cavitation by reducing impeller inlet pressure. The impeller slips more and the engine thinks that it is attached to a smaller impeller.
Current thinking on loader design leans towards evenly loading the impeller inlet top to bottom combined with an impeller that is matched to the engine’s output. Minimize drag while maximizing thrust.
Rock grates are a leftover relic from when driving a jet boat over sand bars was actually an advertised benefit over owning a jet over a prop boat. Rock grates do nothing to help load the pump and will actually restrict pump inlet pressure. You are better off not running anything than running the stock rock grate but, IMHO, you will be very happy with addition of a modern design loader.
Cheers,
Joe
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I will probably try out a rock grate and see if I am happy with the performance. If not the old SE loader will be replaced with a new one. With running in a river, I need something that won't pick up too much trash.
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I will probably try out a rock grate and see if I am happy with the performance. If not the old SE loader will be replaced with a new one. With running in a river, I need something that won't pick up too much trash.
Hey give me a call I have that rock grate
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Sent from my iPhone using SoCalJetBoats