gpm of water to run a mercruiser on hose
 

Putting in a dyno at my shop plus wanting to run boats on hose from well pump. Current pump cant keep up so going to have a new well drilled. How many gallons per minute should i be looking at fory new pump, thanks, smitty

Congrats on your soon to be new Dyno !

I have no hard data for you but I emptied a commercial 250-300 gallon stainless 'sink' within a few minutes with Bravo pump on a dyno. With garden hose still running in to the 'sink.'

So, lack for a better measurement, around here, we'd say you need more than a schit ton. LOL.

Dynos not new, norm schenk from competition fuel systems in tuscon arizona just moved to my town and we are putting it in my shop as a partnership. I guess more than running a boat on a hose, we need to be able to run a motor at wot and not run out of water

So...as an option like I did, I bought a used sink or wash tank or whatever that held that much water. I hooked the drain up to the inlet of the sea water pump. Issue is that it takes a bit for the garden hose to fill it. LOL. Good news was, that it was halfway easy to move outside so it wouldn't be in the way when not needed.

Good luck with the partnership !

I like that idea, could tee a garden hose in like a flush line in the boat to start it and warm up, then close the flush make pulls off the tank.

Norm is a soft spoken engineer type who worked at university lab in arizona grinding telescope lenses for nasa, he is quoted in the holley carburetor book as a carbb expert, he uses the dyno for testing and developmental work, i get to use it as i need at no charge in return for giving him shop space, we are excited

Sounds great Smitty! your building quite a nice shop there Sir! hope to get by and visit with you again soon.

Good thing I have the perfect test mule for you hehe......

Smitty, i wanna say somewhere in the neighborhood of 2500 gallons per minute would be needed

Merc has testing for engine side and water discharge output water volume of the water pump impeller / housing / water flow thru to the sea water pump outlet side.

Basically OEM stock bravo set ups and depending on closed cooled or not and other examples - big block or small block apps

with that said OEM stock bravo the general rule of thump Merc spec is called

SEAWATER PUMP OUTPUT TEST but the boat must be in the water (MERC specs) or IMO a huge bucket of water under the outdrive.

engine ran at 1000 rpms - sea water pump outlet hose off as another hose long enough installed then set in a large enough empty bucket - MERC basic rule of thumb for bravo apps is 15 seconds of run time at 1000 rpms needs to fill the bucket 10 qts of discharge water bare min.

To further break that down the bare min spec thru from the output side of the Impeller housing is 10 gallons per minute again the bare min of water

Jabsco marine says 10 gallons per minute, per 100hp of flow is needed. So, a 500hp engine, would need 50 gallons per minute, or 3,000 gallons per HOUR of flow. A 1000hp deal, would need 6000 gallons per HOUR according to that.

I have a flow chart at home of what the jabsco merc style sea water pump can move at various inlet pressures. Its actually pretty amazing how much water they can move!

Even with a different well seems like you wouldn't be able to keep up. Get one of those big white plastic tanks like they use for horses that hold hundreds of gallons and can be transported in the bed of a truck. Use that as a buffer with your current well feeding it ? I've seen the up to 550 gallons for under $500 new

MT, your math is flawed......it would be 3000 and 6000 gallons per hour not minute...the 1000hp motor would need 100 gallons per minute...

Joe with that volume of water flow you would sink a boat in a minute as no bilge pump in the would keep up with that volume if ever any output hose engine side would ever break or come off while running.

I do not know of any gas side marine water pumps / impellers that could ever pump that much volume water especially thru drive inlets and a 1 inch to 1 1/4 inch inlet and outlet hoses

Can Fire trucks pump that much volume water in a minute / Just asking .

I plan on using a tank to buffer it too but my current well puts out about 6 or 8 gpm for a few minutes plus 40 or 50 gallons from the 60 gallon exp tank, def upgrading as i dont want to stand around all day waiting for tank to fill

Working in the pumping industry i was just thing about this as i came across your posting......looking at my friction loss charts 1" pipe max's out at 50gpm and 1-1/4" pipe max's out at 90gpm.....you would need a hella strong pump to push liquid at those rates....

just did a quick search of fire trucks too....they are running a 2.5" line at 150 psi and discharging a min of 250gpm...but i saw another posting where the pumps on these trucks are now in the 1500-2000 gpm range!! wow!

the output gpm will all depend on how much pressure the pump can make and how much friction its fighting against with th e length of line...the size of the line...any fittings, discharge nozzle size etc...

Yes, typo. I meant to say per hour, not minute.

and do not forget especially with Merc is pulley size & ratio along with belt set ups and pump speed.

there is no way a stock bravo pump is going to pump a 100 gallons per min NO WAY IN THE WORLD and I doubt a gas size crank mounted pump will either that is NOT custom made. You would have to spin that crank mount so fast to get that kind of water volume output ( I am talking about 100 gallons of water output completely discharged) . It can not even completely run thru your engine that fast of a 100 gallons of water per minute. No way you could ever pass that much volume of water thru a t stat alone along with exhaust water jackets especially the restricted riser gaskets.

Well, best way is to test it....Which i should of, but at the time, I was testing more things than i should have ...lol.

Get the dyno set up. Get a big reservoir.....test on 1st engine w/Bravo pump...and then build from there.

Schit, I have many pick up trucks come in here with bedliners that won't let water out with the tailgate up. Fill one of those suckers and have at it....to test of course....LOL.

I've had a hose come off my cooler right after the pump at 70mph. Within seconds, I had a bilge full of water. The first thing I noticed, before even the engine temp climbed, was my bilge pump LED light come on while running.

http://www.pumpagents.com/pdf/Jabsco...43210-0001.pdf

It was a typo. I meant to say those big numbers, in Gallons per hour, not per minute. Obviously, per minute, would be ridiculous.

When Brad dyno'd my engines at Smith Power, he had a primary and secondary pump, the primary was good to about 1500 revs any more and it would start collapsing the hose so the secondary pump would be turned on when power pull's were to be made, 1'1/4 hose hooked directly to the sea pump, its amazing how much water that little impeller will move, congrats Smitty I sold your boat, haha

I know Joe as I am saying in general for the marine gas engine side that they will not even pump 100 gallons per minute. Custom made ones possible but I have never seen it and would have to see with my own eyes. Not directing that post at you.

off the top of my head for Mercruiser black engine side OEM stock

4000 rpms engine speed
bravo apps and water inlet flowed thru the outdrive

bare min water pressure at 4000 rpms for the 4.3 and ALL smallblocks closed cooled apps is 20 psi again bravo apps and seawater cooled apps water pressure 8.5 psi for the 4.3 L and 10 psi for the 5.0L and 11 psi for the 5.7 and 6.2 L. Minimum water flow volume at 4000 rpms 28 gallons per minute for closed cooled for these apps for these closed cooled apps.

Seawater cooled is 13 gallons per min water volume flowed for the 4.3L then 15 gallons for the 5.0L and then 17 gallons for the 5.7 & 6.2 - again this for the min water pressure readings and min water flow volumes @ 4000 rpms for the bravo with these apps installed.

the 496 - 8.1 L is of course closed cooled needs a min of 11 psi water pressure at 4000 rpms and bare min of 20 gallons volume of water flowed per minute. Only 20 gallons for this app but keep in mind that the bare min at bare min of 11 psi for the 496 Mercruiser.

A standard fire ground stream is a 2 1/2" line 200' long, flowing through a 1 1/8" nozzle bore 250 Gpm @ 80 psi. The trucks pump is typically 1250 Gpm @ 150 psi, 885 @ 200 psi, 625 @ 250 if it is a 2 stage pump like the one I'm working on right now.

Glad you sold it! The first thing im dynoing after norm gets the dyno going is my 502 im building to sell my baja with. Fresh short block, mildly ported rectangle port gm heads, my modified 502 mpi intake and bored throttle body off my 540 blower motor with a hp 500 efi cam and morel lifters, i expect between 480 and 520 hp, if it makes 400 or 600 the dyno is off, i will post results. Just spoke to well driller, he says 15 gpm is easy, if we go 50 to 100 feet deeper and bigger on the pump he could get more but he claims water will be nasty and it will cost thousands more. Prob going to get a 500 gallon buffer tank then

If you could some how try to capture some of the exhaust water to reuse it would cut down on you total consumption.

What brand of dyno you bringing into your shop?

Grand Sports center has a prop dyno they`ve been using forever. I don`t think Paul visits here too often but I bet he`d know how they run it. Ask for Mark I bet he`ll tell ya.

Otherwise do you have one of these close by ???


http://ak.picdn.net/shutterstock/vid...eo-footage.jpg

I'm guessing if he has a well prob not lol

Mine popped off the discharge side of the pump coming on plane and pumped the 27' full within 100 yards/seconds. Bilge pump ran for 45 minutes.

Never been on a well but yeah that makes sense! LOL

Off subject but when you`re on a well and your house is on fire the fire truck brings their own water and when they run out you`re sol?

"Well, were out of water, who brought the marshmallows and sticks?' lol

Trying to tie in all the bits and pieces others have said and from my own experience running on a stand with a Bravo pump I offer the following:

Pump flow rate is in the 10-70 GPM range.

Don't try to feed the pump, let it 'eat' from a large source/reservoir.

Keep the input flow from hose/well/ etc. at max rate

Try to recoup exhaust water to the max extent possible.

Total volume of reservoir will will determine max run time.

At idle to 1500 rpm I could drain a reservoir of about 2 x 4 x 1 ft dimensions with an input of 5 gal per min and recovering about 80% of the exhaust water in about 3-5 minutes. Watch the intake hose so that debris doesn't get in the way. I had a rag fall in the tank....ooops. Caught it quickly though.

Need to keep in mind, these flexible impeller pumps, flow a different volume of water when they are sucking, compared to what they flow, when being force fed, like in a boat at speed. .

Smitty, anyway you could simply buy one of those big plastic tanks, mount it up higher than the dyno, run a decent sized pipe to the engine area, and let gravity handle feeding the sea pump assembly, rather than trying to 'suck' the water from the tank? Then use a well pump to refill the tank back up when it runs low.

[QUOTE=ICDEDPPL;4363538]Never been on a well but yeah that makes sense! LOL
They call the fire department where i live " the foundation fire dept" because they can usually get fire out about when it reaches the foundation! Alot of houses out here have ponds for fire reasons , not just looks. To me its just a mosquito breeding grounds

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As far as running on the dyno, the place that did mine had a tank about the size of a hot water tank that recirculated the water. The water temp rose from 165 to 175 during the pull. You can see the tank on the left