Wanting to build a couple of dredges

[OldGoldJunky]

Howdy folks,

I'm looking to build a couple dredges; a 2" for piddling around and a 4" for serious work. The 4" will be mounted in a flat bottomed jet boat for ease of getting up and down the area I intend to dredge. I'm wanting to get away from having a gas motor and pump directly on the dredge. My idea is to have a 120V pump that I can plug in to a little 5000 watt generator. What I'm having problems finding is the required GPH to make both of these dredges work. Hoping you all can point me in the right direction

Bob

 

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[NeoTokyo]

Whelp the Keene P180 used on their 4" is 250gpm and can do 300gpm.
Recommended horsepower is 5.5hp - 6.5hp.
Head is 161 feet and from what I have read online, psi is about 30-35.

Keene's P90 which is used on their 2" dredge is 100gpm and 161' of head.
This pump requires a minimum of 2.5hp.

I found (And lost) a helpful chart online that showed just how much GPM that you would need for each step up in dredge hose size.
Hopefully someone knows what I am talking about and will post a link or share the photo.

Good luck with your build and welcome to TNet.

 

[OldGoldJunky]

WOWZERS!!

So I'm guessing a 2000 GPH pump will barely get it wet.

The reason I'm trying this route is to keep generator noise down. I may have to re-think this.

Thanks for the reply


Bob

 

[NeoTokyo]

You could always swap mufflers on a Honda engine or H.F. Predator clone for Honda Generator mufflers.
They are usually more quiet but restrict flow even more.

2000gph wont cut it for sure.
There are much high flow 120v pumps out there, check out pond pumps because they usually have high pressure and head and are meant to go non-stop for their entire working life.

 

[OldGoldJunky]

You could always swap mufflers on a Honda engine or H.F. Predator clone for Honda Generator mufflers.
They are usually more quiet but restrict flow even more.

2000gph wont cut it for sure.
There are much high flow 120v pumps out there, check out pond pumps because they usually have high pressure and head and are meant to go non-stop for their entire working life.

Did a quick look and dont see anything close to 300 GPM. Looks like I'll have to go gas powered on this build


Bob

 

[russau]

you could ALWAYS replace the muffler on the gas motor with a "low tone" replacement muffler! Hoser always recommends it! I was going to get one for my 4 inch dredge but it was still in great shape and those mufflers NEED TO BE US Forrest service approved with the stainless steel mesh in the muffler as the spark arrester. don't get caught without one ESSPECIALLY on the West Coast! I have a two stroke engine for a tow inch very light weight dredge I built and im planning on replaceing that muffler for sure!!!

 

[mike(swWash)]

You can also run the exhaust pipe to exit under water to silence it.

 

[russau]

You can also run the exhaust pipe to exit under water to silence it.

if you do this , youll have problems if that engine backfires or you create back pressure and ruin that engine! Ive heard this over and over NOT to do!

 

[DizzyDigger]

You can also run the exhaust pipe to exit under water to silence it.

if you do this , youll have problems if that engine backfires or you
create back pressure and ruin that engine! Ive heard this over and over NOT to do!

Russau is right Mike, not only can it suck water right into the cylinders, it's also dumping that
foul exhaust right into the water where the fish live. Don't know if it would kill fish in the immediate
area, but it sure wouldn't be good for 'em, and the eco-wacko's would have a field day telling
everyone about it.

Gotta be a better way.

 

[nh.nugget]

I have a Harbor Freight 2" pump on my 3" dredge I built and it's not that loud the over head valve engines are a lot quieter than the old briggs. The way the exhaust is on my pump you could accually put a second muffler on it with a little macgivering

 

[Al(GA)]

I have a Harbor Freight 2" pump on my 3" dredge I built and it's not that loud the over head valve engines are a lot quieter than the old briggs. The way the exhaust is on my pump you could accually put a second muffler on it with a little macgivering

nh nugget --- I also got one of the 2" clear water pumps from harbor freight and removed the pump . The 212cc engine it comes with is basically a Honda clone. So I got a keene P180 pump (keyway version) and it bolts up perfectly to the 212cc engine. Just a heads up if you ever want to increase the power of your dredge.
I love that engine/pump combination --- it starts every time, runs quiet and is very reliable. I use it on my Summit Minning dredge/highbanker combo which is adjustable from 2.5" to 4" suction hose. Note: if you go with the P180, use keene's 2.5" footvalve and hose for the intake (for maximum performance).

Al

 

[OldGoldJunky]

I have a Harbor Freight 2" pump on my 3" dredge I built and it's not that loud the over head valve engines are a lot quieter than the old briggs. The way the exhaust is on my pump you could accually put a second muffler on it with a little macgivering

Does that pump work pretty good Nugget? I looked it up and it advertises 9540 GPH which works out to 159 GPM. Hey if it works it works

 

[Hoser John]

GPM means nothing without PSI and wimpy at best even in shallow water. Try a real pump and the truth is self evident. John

 

[nh.nugget]

I don't know about wimpy, it has like 40 something psi I know it will blow out a flat hose like nothing! been there. It has plenty of suction on my 3" dredge. Hey for $150.00 as opposed to what 5-600 each? Buy 2HF'S have twins you'll get plenty of pressure and suction then. Not to mention double the pleasure double the fun. Check out my thread Got my home built dredge in the water.

 

[Hoser John]

UNTIL it hits the restrictions within a powerjet or suction nozzle, then you lose, as it just goes around and around inside that tank aka pump housing. Backpressure is the trash/semisolid/clearwater pumps demise in efficiency. John

 

[nh.nugget]

I don't know it does a great job of pushing gravels through my dredge. Haven't had any issues yet. And I run a jet in shallow water the river I dredge in isn't very deep, hasn't even plugged at the jet. And I run a lot of dirt! Plus I only run it at half throttle. For $150.00 I'll run 2. The cheapest Keene p180 pump I found just a pump was $735.00 no motor. As long as it sucks dirt gets gold who cares. Musta' done something right when I built my dredge.

 

[Al(GA)]

nh --- Keene retails the P180 for $385 (on their website store) but the keyway version (same price) which fits your motor, is available with a phone call to them. The model listed on their website is for a threaded shaft engine.
Glad to hear the clear water pump works for you (it didn't for me). Having used the Clearwater pump (supplied with engine) and the P180 pump (on same engine), I can attest there is a big difference in performance with the P180 (John H. is dead on with his explanation).

Al

 

[russau]

John usually is!

 

[mike(swWash)]

I understand the possible problems and misunderstandings with an extended underwater exhaust but a 4 stroke won't put oil in the river and only the last 2-3" need be under to quiet it down to almost nothing, otherwise outboard motors would never keep running and be outlawed on all rivers. 2 strokes are a whole different thing, smoke puking, oil slick pizzers that they are. Truth be told I wouldn't do it either.....just an option

 

[nh.nugget]

I'm sure that with age it probably will give me problems. Due to sands going through it not that I suck up sand with it. Any pump is subject to wear. Even the keene too will wear I know the tolerances are tighter in a keene it' basically a small engine driven turbo.