4" Trevs Subbie dredge.

[principedeleon]

Hello everyone. .
I have been gathering parts to try to build a 4" trevs suitcase dredge. .
And i have found a Keene P90 pump and i been trying to power a 4" suction nozzle but not getting great results. .

Ima try to reduce all friction lose in my suction nozzle to see if i get better results.

I have made the jet at the nozzle 1/2 " and my inlet 1" since i couldnt find 1 1/4 hose.

My suction was strong enough for 2" rocks but it was struggling with the larger rocks.
Looking to get the best out of it in 4" instead of running a 3".

Let me know what ya think. .
Thanks.

 

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[Jason in Enid]

I think you are going to have a heck of a hard time with that setup. First, to address the FL comment... you are massively increasing FL by dropping from 1.25" hose to 1". I know that doesnt seem like a big change, but the FL change is huge. Thats the very reason fire departments all moved from 1.5" attack lines to 1.75"

Secondly, a P90 pump is woefully underpowered to run a 4" floating dredge. I know there is improved performance when you go subbie but I don't know if you can move enough water with it.

Third, are you saying you are using a power nozzle? You are going to lose more power from the FL going to that (plus any bends / kinks). I would much more recommend a powerjet, and then just a regular suction hose and tip.

 

[arizau]

I'm not a dredger but it seems to me that if you weld a rounded X across the nozzle opening with a couple of rods then that would limit the size of rocks sucked up and solve your problem (?).

Good luck.

 

[Jason in Enid]

I'm not a dredger but it seems to me that if you weld a rounded X across the nozzle opening with a couple of rods then that would limit the size of rocks sucked up and solve your problem (?).

Good luck.

No, this is the wrong way to go. The entire point of making your dredge (and therefore the dredge hose diameter) larger is to naturally handle larger cobble. The more you can process through the box, the less you have to stop and remove by hand, which speeds up the total processing rate.

 

[principedeleon]

I think you are going to have a heck of a hard time with that setup. First, to address the FL comment... you are massively increasing FL by dropping from 1.25" hose to 1". I know that doesnt seem like a big change, but the FL change is huge. Thats the very reason fire departments all moved from 1.5" attack lines to 1.75"

Secondly, a P90 pump is woefully underpowered to run a 4" floating dredge. I know there is improved performance when you go subbie but I don't know if you can move enough water with it.

Third, are you saying you are using a power nozzle? You are going to lose more power from the FL going to that (plus any bends / kinks). I would much more recommend a powerjet, and then just a regular suction hose and tip.

Okay i could always try to continue to look for a 1 1/4 hose or adapt a 1 1/2 hose on it. .

But trying to run a power jet is not good in a subbie dredge. .

I have ran my 6.5 hp p180 pump 3/4 with super great suction On a 6" suitcase dredge.

Steve ran a subbie with 15 feet of 4" of hose with his sluice mounted under a frame running a 4hp pump with plenty of power.

A suitcase dredge uses a quarter of power less atleastt.
I have tried both setups with my 6" and i was able to run harder at 3/4 RPM then Full throttle.

Meaning i should atleast with the p90 get a good suction @ full throttle.

I believe there is little things like the ones you explain that are killing my flow from the pump and also in my suction nozzle welds in the bend and a non flare jet tip which is creating a backpressure.

Im thinking of trying to bend the pipe all together in one or removing the bent pipe and testing it without the bend. .

 

[N-Lionberger]

You need a suction nozzle on a subbie, a power jet will mess up recovery in the tiny sluice section, the suction nozzle gives the material a chance to stratify in the hose before hitting the box. I'd rec a 1.5"x2" pump, neck it up at the pump to run a 2" hose to the nozzle.

 

[principedeleon]

Okay quick update. . I have found the 1 1/4 " hose. Im looking forward to make everything more effiecient before giving up. .

Also my water pump outlet is faceing up instead to the side. .
Dont know if that would cause a pressure lost...

Well ima start taking one step at a time changing everything.

 

[winners58]

I used a 3 1/2hp p100 pump to run a Keene 4" sub dredge using a suction nozzle with 1 1/2" hose, went from a 1 1/4 outlet on the pump and
used the 1 1/2" lay flat hose on my 2 1/2 dredge my thinking was that larger hose would have some place to build a little more pressure.
my 4" hose was only 6 feet long the sub just settled in behind where I was working, mostly moving overburden, then run the 2 1/2" to clean bedrock.
I have a shop built 4" twin log powerjet that used 1/2" orifice had to drill them out a little bit bigger maybe do some experimenting.

. my sub-dredge and the p100 it was powered by
.
.

 

[principedeleon]

I used a 3 1/2hp p100 pump to run a Keene 4" sub dredge using a suction nozzle with 1 1/2" hose, went from a 1 1/4 outlet on the pump and
used the 1 1/2" lay flat hose on my 2 1/2 dredge my thinking was that larger hose would have some place to build a little more pressure.
my 4" hose was only 6 feet long the sub just settled in behind where I was working, mostly moving overburden, then run the 2 1/2" to clean bedrock.
I have a shop built 4" twin log powerjet that used 1/2" orifice had to drill them out a little bit bigger maybe do some experimenting.

. my sub-dredge and the p100 it was powered by
View attachment 1711453 . View attachment 1711454
.

Nice build winner... .

Im looking to use only 3 feet of hose before entering a 3 feet sluice box. .
Not planning on digging past 4 feet of overburden.

So in my case should i get a a 1 1/2 or the 1 1/4 outlet hose ?

I have tried to see how it fits but there's a big gapp between both sizes.

A quarter inch might be a lot of flow im missing out on. .

 

[Jason in Enid]

You need a suction nozzle on a subbie, a power jet will mess up recovery in the tiny sluice section, the suction nozzle gives the material a chance to stratify in the hose before hitting the box. I'd rec a 1.5"x2" pump, neck it up at the pump to run a 2" hose to the nozzle.

I had to research this Trev's dredge, now I understand better. I was thinking this was just a hanging subbie, not a short hose system. Yeah, I see that the suction nozzle would be needed for this.

 

[Jason in Enid]

Okay quick update. . I have found the 1 1/4 " hose. Im looking forward to make everything more effiecient before giving up. .

Also my water pump outlet is faceing up instead to the side. .
Dont know if that would cause a pressure lost...

Well ima start taking one step at a time changing everything.

No, youre not losing anything from the pump outlet pointing "up", but you do run a bigger risk of your hose kinking. Its a smoother, and better route if it can come straight out.

 

[principedeleon]

Im thinking of eliminating the bent pipe of the suction nozzle and bend the inlet hose instead to try not to kill the flow too much and reduce it right at the jet ..

Also i believe ima have to open up the jet size a bit larger then 1/2 " .. the 1/2" jet could be creating too much unneeded pressure. . I was able to blast water like 25 feet away with the 1/2" nozzle. .

Could i try using a 3/4 " jet at the nozzle? .

Since the system is short and the pump a little under pressure maybe a 3/4 " nozzle the way to go....

 

[Jason in Enid]

I would suggest sticking with commercial made suction nozzles. They have a lot of research and testing behind them already. It "could" be a very long and frustrating road to begin designing or modifying your own. There is a lot of math behind the reduction, and its primarily created with a specific pump output in mind. If it's too small, you don't get enough "push" to create the best suction. If it's too large you don't have enough pressure with the flow to create the best suction.

ETA- as I think about this more... you may need to create your own. I don't think there has been a suction nozzle made for a 4 inch dredge being powered by a P90 pump. I would actually suggest calling Keene and talking to one of their engineers about your needs. They probably already know how a nozzle would need to be designed for that combination.

 

[winners58]

I have had the p90 on a two stroke my brother had one on a Honda GXH both could run a 2" nozzle
they put out more water like for a highbanker by using high RPM's 6000-7000rpm
might be asking too much for that pump, maybe try a 3" nozzle and hose and adapt going into your box...

 

[Timberdoodle]

Hi P,
I would increase orifice size to at least 3/4. The keene 2" log jets are actually 5/8" to better match the pump/honda engine they have been using for many years now. You mentioned having a p90 pump. Is this on a honda ghx50 engine or something else? I ask this because as Winner mentioned above the ghx50 engine is a 7000rpm pump and makes for a stronger pump than a 4 stroke running at 3600rpm.

You can increase the outlet of the pump to 1 1/2" using an adapter and then run 1 1/2 hose. I have been using my honda ghx50/p90 this way for many years. The 1" hose is certainly killing some of the power available due to friction loss as Jason mentioned.


Were you using a quad jet for the 6" subbie? The p90 is really pushing the limits without gaining some efficiency from a better jet. What were the 6" jet orifices?

 

[principedeleon]

Tim. . I have a 4 stoke gxh 50 engine. .

On my 6 " subbie i have just a straight 1 inch pipe with no reducion on the end. .

I was running it with a 6.5hp p180 pump .. i ran it about a bit less the 3/4 throttle..


I was thinking of making the pressure inlet 5/8 because i think 1/2" just might not have strength too create enough suction..

 

[jsurddy]

A few years ago I saw a sub dredge on craigslist that used a jet-log design but put the Venturi jet after the sluice box. It kept the turbulence caused by the jet down-stream of the sluice where it wouldn’t effect the stratification of the material. That design would need to have a pretty good seal around the sluice to keep from loosing efficiency, but seems like a pretty good design.

 

[Timberdoodle]

It has been my experience that going from a surface to a subbie reduces the power required to run to about 1/2. This means that a subbie dredge can use the same engine/pump combo to run a dredge with twice the hose volume of a surface dredge.
In the case of the 6" subbie you used a pump/engine combo that runs a 4" surface dredge.
4" hose has 12.5 square inches of volume
6" hose has 28.2 (just over twice the volume)
8" hose has 50.2 (4x the 4" hose)

In the case of the 4" subbie you are trying to build the pump/engine combo is generally rated for a 2 or 2.5 dredge.
2" hose has 3.1 square inches of volume
3" hose has 7 (just over twice the volume)
4" hose has 12.5 (4x the volume of a 2" hose)

So stepping up from 2" to 3" is basically the same as 4" to 6". The problem of trying to go from 2" to 4" means some other system improvement like gaining efficiency from a better jet and/or reduced hose length is probably necessary to get good suction.

 

[principedeleon]

Wow JS. Never heard of that kind of subbie pretty interesting.
In my case i would be building a square sluice box which would make addapting a jet at the end pretty complicated.


And Tim .. i was actually thinking the same thing..
I was'nt even running the 6.5hp engine at full rpms. Just a bit higher from 1/2 throttle.
Meaning i had to be running about 180 to 210 GPM. .
Calculating from the specs of what keene says there p180 produces which is 300gpm . .
What im going to do is change the hose to 1.5" and probably i could get away with 13' of hose cause i dont want to be too close to the engine and pump. .
And ima try to go with a 3/4 " jet at the nozzle which i believe is half of the 1 inch jet that my 6" has. .


My plan is trying to get a good suction around full throttle because i know i wont be able to get a good suction with anything less. I know is not so good for the engine but carrying a heavier engine with more things aint good for me hehe. .

So isnt a suction nozzle that is pointing straight down the pipe more effiecient then a power jet ?? .
A single log power jet sends the rocks to the other side wall of the jet; while the suction nozzle sends it down the pipe. .

The only down side i see about a suction nozzle is the inlet pipe bend and pressurizing a foot or so before entering the jet which causes a pressure lost.

This is why ima try to remove the suction nozzle bent inlet to a straight short one where all the water is going to do is focus into the jet. . This is the best way i could think of making the suction nozzle more efficient..

Well today is monday let me see if i could get some things done.

Thanks everyone for ya help. .
Hopefully this time i could better results.

 

[Jason in Enid]

I dont think the suction nozzle loses much (if anything) due to the curve. That kind of thing comes down to radius of the bend (and quality of the bend). If the bend is too tight, then you are going to have problems with turbulence. Also, if the bend if poorly made and has wrinkles in the inside bend, that is going to cause issues. Looking at the wide bend of the typical suction nozzle, I don't see either problem.

Another consideration, you are talking about basically using a jet-log as a nozzle but as you said, that input blasts water across the pipe (turbulence). The shape of the suction nozzle pushes the water straight back down the pipe so you will have much less turbulence in that very short section before the box.