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Dredge Pump and Power jet Performance Mods

Its just about that time of the year where we start getting back in the water. Most of you will be itching at the thought especially where with the current gold price where its at!

Thought id start a thread on how to get the best out of your pumps and power jets so as to increase efficiency that pretty much anyone can do

Ill outline whats ive seen that works for me and others. This is especially relevant to those of you with Proline or Keene pumps.

Lets start with the impeller:

In this photo you can see the underside of the impeller as pointed out by the arrow. The aim here is to remove some of the material on the underside of the impeller. This is called underfilling the impeller. Impellers that respond well to trimming usually have a decent amount of material to remove.

Another technique is to remove the material on the pressure or face of the impeller as per the diagram above. This is called overfilling. Be careful not to remove to much material. Make sure each vane on the impeller has the same amount of material removed so as to keep the impeller in balance.

The idea behind trimming an impeller is to increase flow or GPM and also increase pressure or head. Overfilling increases pressure or head by increasing the “throw” of an impeller while underfilling usually increases the flow of a pump.

Use a file and remember to take it slow and make it uniform. Small changes make big differences as you are only removing a little bit of material. I’ve noticed a 10% improvement in pressure and generally a 5% increase in flow just by doing these mods. The Keene P180 and Proline HP400 respond well to this.

Another thing you want to do is smooth out any burs or imperfections in your impeller

In this photo you can see an example of this. The aim here is to ensure this surface is smooth and sharp. This will increase the bite the impeller has on the water entering the pump as well as increasing flow. Be careful not to remove to much material as this can have the opposite effect.

Another thing you want to ensure is the pressure or leading edge of the impeller needs to be rough. This increases the grip the impeller exerts on the water it is accelerating thereby helping ensure good flow withing the pump.

One of the most important things you can do is particularly on pumps like the P180 is ensure the inlet eye is hard up against the impeller inlet. Here is a pic of what I mean

What your trying to do is limit the amount of water that can make its way back into the inlet eye. This is called eye leakage and you want to limit this as it will cause a reduction in pressure of the pump particularly at high RPMs
Use a wooden mullet to gently hammer the plastic eye so it is hard up against the impeller. You want to have some resistance when you turn over the pump when starting (but not too much)

Another technique is to use silicon sealant to do the same job as per the photo below

This helps to ensure a good seal between the inlet ey and impeller inlet. This is useful on pumps with a non adjustable eye inlet like Proline and Keene P350 and PHP500

Another technique is to bore out the inlet eye and smooth out any imperfections

As you can see in this photo the white arrow shows a lip created you want to smooth out and make a nice transition. This reduces turbulence within the intake of the pump and ensure better flow

Note the red arrow is shows the bit you need to remove if you are to hammer in your eye.

You will see in this photo how much restrictive the inlet is on the pump. The airm here is to bore out the inlet and match it in size to the impeller eye diameter. This increases flow to the pump which translates usually to a 2% - 5% increase in GPM of the pump. It might not sound like much but combined with other techniques translates to better suction at the nozzle


For Power-jets there are some things you can do weather it be a homemade power jet or one from one of the manufactures

I’ve found the Proline power jets to be the best. They are ultra efficient and machined very well. Here are some examples

Here is a 6 inch Keene powerjet . As you can see highlighted in solid red arrow is a lip created during the welding of the educator onto the powerjet. This lip has the effect of disrupting the high velocity column of water that enters the powerjet thereby reducing suction and causing a whole lot of unnecessary turbulence within the water column which can effect fine gold recovery. You can remove this lip with a grinder. Net effect is about a 3-5% increase in suction depending on dredge

The other red arrow shows the void created by the welding the of the jet onto the powerjet which allows rocks to flip within the jet thereby increasing the probability of an annoying rock jam

As you see in the below photo of a Proline 5 inch powerjet they have eliminated this

See how smooth of a transition the jet as it enters the powerjet. Notice there are not imperfections that the water column is going to be impinged by. This is one of the reasons Proline dredges have a reputation for some serious suck

Another photo of a Keene power jet. Almost enough space in that jet to have a party.

So when designing your own powerjet take into consideration these factors

In this photo you can see the jet log and its conical reduction from approx 2 inch down to just under an inch.
For those of you wanting to build a jet the best method is to design a concentric reducer. Don’t use a nut or washer as you loose efficiency.
The idea of a conical reducer is to increase the velocity of the fluid coming from your pump so as to impart that high pressure jet of water onto the slower water column coming up your dredge hose and into the powerjet. this creates the venturi effect.

Powerjets efficiency work on a combination of water velocity and water volume from your pump.


Nice Post. Good on you

Great info what sort of gain in suction do you get with doing this?

hey good read Prich , you forgot to mention the phycological effect on the dredger when he discovers a 16 ounce nugget jammed in this powerjet

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Thats a hard question as it depends on your gear. But I’ve seen a doubling of suction on some setups with less blockages and the ability to run your engines at lower rpm.

On a dredge like a dredgenz dredge ive seen a easily a doubling increase in suction

On the Keene setup like the 4 inch you can easily get 25% and on the 5 and 6 inch setups about the same.

On the Proline setups usually a 10% increase as they are pretty efficient already

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I liked it, very informative.