Water Pump Output (GPM)

[avocado]

Anyone have an idea of what the output is on a water pump for a 1984 1.6 turbo diesel?

Or specifically, what the water flowrate would be to the heater core?

It appears that 20-40 gallons per minute (GPM) is a standard range for smaller vehicles, but I'm trying to do some cooling calculations, so I thought I'd inquire if anyone had firmer numbers.

Cheers,
Avo

EDIT: My next step will be to use a bucket and calculate the flow that way, but I thought I'd ask first.

[DanHoug]

a standard garden hose, running strong on city water pressure is about 5 gpm. t'ain't no way there's 20-40 gpm thru the heater core but possibly the coolant system at high rpm. *maybe* 2 gpm thru the heater core from what i've seen.

i put a simple 3/4" T in my heater hose circuit to feed the run to my veg tank in the trunk. this same run also has in series a Modine heater i installed on the rear passenger hump. fantastic heat output. interestingly, with the T in place, my OEM heater output did not decrease.

once it gets up to temp, my Jetta is now the warmest car i own. but at -35F, it can take 20 miles to warm up!

-dan

[avocado]

a standard garden hose, running strong on city water pressure is about 5 gpm. t'ain't no way there's 20-40 gpm thru the heater core but possibly the coolant system at high rpm. *maybe* 2 gpm thru the heater core from what i've seen.

Ah yes, I actually meant 20-40 gpm for the whole pump. If you figure the heater core gets about 1/4 of the flow (maybe less given the restricted hose diameter compared to the radiator) then maybe it's more like 12-15 for the whole pump (although that sounds a bit low).

i put a simple 3/4" T in my heater hose circuit to feed the run to my veg tank in the trunk. this same run also has in series a Modine heater i installed on the rear passenger hump. fantastic heat output. interestingly, with the T in place, my OEM heater output did not decrease.

Interesting. This is a good sign as it tells me the pump is probably oversized for the application and removing some of the flow didn't have a negative impact. Thanks!

Full Disclosure: I'm fiddling with water stuff on my VW Camper conversion project, and trying to get an idea of how modifying the system is going to affect things. I know this has potentially detrimental impacts, so I'm trying to tread carefully and do the calcs before I make the mods...

[DanHoug]

i put a booster pump in the heater circuit of my water cooled Westy, gasoline to try to boost heat output. if the diesel Westy coolant system is as poor as the gas, it is smart to redesign it.

one issue is those coolant pumps are high volume, low pressure. so the long run up to the front causes enough resistance to reduce water flow.

there's lots of electric coolant pumps for the racing world but they really are only designed for 1/4 mile runs. Mercedes makes a continuous duty coolant pump that i always wanted to get ahold of for the Vanagon.

-dan

[joat]

PONY pumps make several 12V impeller units that could be modified to suit.

make sure the seals and impeller are the viton versions for high temps and antifreeze.

[DanHoug]

yup. i used a Jabsco Centri-Puppy, similar to the PONY series, that was rated for some heat. but it had a conventional seal and it started leaking. i took the pump out, replaced the seal with a Viton one, and now pump 200F veg oil with it no problem.

[avocado]

i put a booster pump in the heater circuit of my water cooled Westy, gasoline to try to boost heat output. if the diesel Westy coolant system is as poor as the gas, it is smart to redesign it.

one issue is those coolant pumps are high volume, low pressure. so the long run up to the front causes enough resistance to reduce water flow.

Did the booster pump help, Dan?

I'm not going all the way up to the front of the bus (only to the middle where the heater is set up under the bus) but I'm still worried about the pressure drop, especially through the rubber heater hoses I'm using...

[DanHoug]

the booster pump helped the heat output for the front and middle heaters. tell me more why you are interested in only the middle heater... if anything, the middle heater was always pretty good. it was the front that needed more flow thru it.

the underseat heater has a heat control valve. that isn't partially closed is it?

-dan

[avocado]

This is for an air-cooled bus, to the only heaters are the aftermarket ones I've installed.

So basically I bought an aftermarket, pre-packaged heater from Summit Racing and installed in under the floor of the bus (just about under the back seat) and have the hot air ducted through the original air-cooled heater ducting.

The heat blows pretty hot (then again, it's summer), but I'm thinking about installing a second heater core either inline or in parallel with the heater core to use as an aux radiator, and I'm worried about getting enough flow.

[DanHoug]

ah. an aircooled converted to diesel? very cool. where'd you mount the radiator?

i would run the heaters in parallel, not series. if you can, make a large diameter manifold (1.5" would be great) to feed the heaters, T off of that with 3/4" diameter hose to the heater, and return it to the engine with another large diameter manifold. but realistically, 2 separate runs of 3/4" from the outlet of the head will probably be pretty good.

you want to make sure that there is full flow thru the cores at all times, don't turn off the water valve on the Summit heater. i feel the decrease in back pressure by having these passages open at all times, in addition to the normal return to the pump, helps extra coolant flow thru the head and keeps the cracking between the valve seats down, as well as better protecting the head gasket.

i used that same Summit heater in my Jetta... terrific heat out of it.

-dan

[vanbcguy]

I used a Bosch pump for my air/water intercooler that is rated for automotive cooling use. It flows GOBS of water and would make a perfect auxiliary pump for these types of applications. Look for a "Bosch Cobra" water pump - nice and small, flows like crazy and has a decent enough life (should last 100,000 miles if powered on whenever you turn on the key).

There's also an auxiliary coolant pump that was used on the VR6 cars, it is basically a smaller version (lower capacity) than the "Cobra" pump.

[avocado]

I used a Bosch pump for my air/water intercooler that is rated for automotive cooling use. It flows GOBS of water and would make a perfect auxiliary pump for these types of applications. Look for a "Bosch Cobra" water pump - nice and small, flows like crazy and has a decent enough life (should last 100,000 miles if powered on whenever you turn on the key).

There's also an auxiliary coolant pump that was used on the VR6 cars, it is basically a smaller version (lower capacity) than the "Cobra" pump.

nice! Thanks for the tip!