Partofthechaos
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| posted on 23/11/22 at 01:12 PM |
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Water Pump Thoughts Welcome
Hello All,
I am going round in circles (pun intended) with coolant pumps. Going off piste from my build manual means that is not giving me any support, so I
thought I would ask the amazing people here!
It seems convention is to put the pump on the cold side of the rad, pulls from the rad and pushes into the engine. Then hot from the engine to top of
the rad, if the ECU controls the pump then no thermostat required. With that sorted, my next step is get get the flow rate correct.
My engine is a 3L, car builder solutions indicate that a Davies Craig pump at 80L/min with a draw up to 7.5A is sufficient for a 5L engine so that
should be fine for me. https://www.carbuilder.com/uk/electric-water-pump-only-80-lmin
However, a Pierburg CWA200 which BMW use on 2L engines can do 116L/min+ (dependant on pressure) at 15A.
https://tecomotive.com/store/en/water-pumps/pierburg-cwa200-water-pump
As the Pierberg is twice the amps, I imagine it is working approximately twice as hard and will definitely shift more water, but is rated for a much
smaller engine. So does that mean that one of these is over / under rated? Or am I missing something to do with flow / load / pressure etc? I
don't want to spend massive money, but these aren't too different on cost and not something that is worth skimping on.
Any thoughts gratefully appreciated!
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CosKev3
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| posted on 23/11/22 at 01:42 PM |
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I went for a Davies Craig 130 to start with as that should have been upto the job,it wasn't.
Then I tried the 150,which still wasn't good enough.
Then I discovered Pierburg pumps and Tecomotive controllers and the CWA200 worked fine when my car was NA,but once turbocharged I now run the CWA400
with a 75mm cored aluminium rad with a very strong Derale fan imported from the USA and now my temps are well under control,even on summer days on the
track.
Big difference between the Davies Craig and Pierburg pumps is how they cope under a bit of pressure in the system,Davies Craig pumps performance drop
off a cliff with slight pressure in the system where as the Pierburg don't.
When I was having cooling issues doing some Googling and all of a sudden the Penny dropped and a V6 compared to a 4 cylinder engine makes a lot more
heat as you have two more cylinders,even worse when you go to a V8 with 8 explosions of heat to disperse!
Hence why V8 Westfields always have cooling issues.
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nick205
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| posted on 23/11/22 at 01:53 PM |
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CosKev3 seems to have some real world experience for you.
My thoughts:
1. Are the BMW Pierburg and Davies Craig pumps both 12V? If their designed to work at different voltages that may account for the different
currents.
2. Car manufacturers (e.g. BMW) are very good at standardising parts across their car ranges to reduce manufacturing costs. With that in mind BMW may
fit the same water pump to larger engined cars in their range as well and simply drive them harder. The pump may rated at 15A max. in the smaller
engined cars are they actually supplying 15A to it?
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Partofthechaos
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| posted on 23/11/22 at 07:27 PM |
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quote:
Originally posted by CosKev3
I went for a Davies Craig 130 to start with as that should have been upto the job,it wasn't.
Then I tried the 150,which still wasn't good enough.
Thanks Kev, as Nick says, application of those pumps on the same engine is very useful information, based on that I wont be going for a Davies Craig.
It also sounds from your experience that a CWA200 should be fine for my setup.
quote:
Originally posted by nick205
1. Are the BMW Pierburg and Davies Craig pumps both 12V?
2. Car manufacturers (e.g. BMW) are very good at standardising parts across their car ranges to reduce manufacturing costs. With that in mind BMW may
fit the same water pump to larger engined cars in their range as well and simply drive them harder. The pump may rated at 15A max. in the smaller
engined cars are they actually supplying 15A to it?
1. Yes both 12v as far as I can tell, the Pierberg definitely is, the one on carbuilder doesnt say, but as its avertised for cars it should be.
2. Yes that is quite a likely senario, either different cars or different engine options in the same car. I suspect the 15A is its maximum working
draw, I was just suprised how much higher it was than the Daniel Craig version (much better name). I think Kev has answered that one too in a way, it
sounds like it is a higher torque pump.
OK, next question, where to get a Pierberg CWA200! The one on t7design.co.uk is £264, while wanting to avoid the imitations I will steer clear of FB,
eBay etc. Thats the best price I have found so far.
Thanks both for your comments!
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Partofthechaos
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| posted on 23/11/22 at 07:31 PM |
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Kev, do you have any pictures of where you mounted your pump please? I can either attach it to the block or the chassis, but the chassis is all
narrow round tubes that I don't really want to drill into if I dont have to. So leaning towards a block mount, is that what you did?
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CosKev3
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| posted on 23/11/22 at 09:26 PM |
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quote:
Originally posted by Partofthechaos
Kev, do you have any pictures of where you mounted your pump please? I can either attach it to the block or the chassis, but the chassis is all
narrow round tubes that I don't really want to drill into if I dont have to. So leaning towards a block mount, is that what you did?
No mines on a bracket I made between chassis rails,so its positioned down low in front of the bottom pulley.
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falcor75
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| posted on 24/11/22 at 07:57 AM |
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Just another chime in to avoid the Craig Davies pumps. I have seen a few build threads where they either dont perform to specs or dont last very long
and needs to be replaced within 18-24 months. Better to cry once and get something that works.
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Partofthechaos
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| posted on 24/11/22 at 11:01 AM |
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Noted, thank you. Pierburg it is!
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BenB
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| posted on 28/11/22 at 10:09 PM |
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quote:
Originally posted by falcor75
Just another chime in to avoid the Craig Davies pumps. I have seen a few build threads where they either dont perform to specs or dont last very long
and needs to be replaced within 18-24 months. Better to cry once and get something that works.
He should have spent more time designing the pumps and less on chilling all Sunday. Oh hang on..
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sdh2903
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| posted on 29/11/22 at 08:02 AM |
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Just to add another review
I have the same engine and run a Davies Craig 115 pump and electronic controller. Even with a shite coolex rad the cooling has always been well under
control on the road and brief stints on a sprint circuit.
I now have a bespoke 50mm rad as big as will fit in a Westfield nose and if anything I'm overcooling. However am about to fit a laminova now I
have cooling headroom to help with oil temps.
So the DC pump has been spot on for the past 2 years. However if buying now I would too follow Kev's lead and go with the pierburg. They are
built like brick outhouses and designed to do 100k in a road car.
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loggyboy
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| posted on 29/11/22 at 09:54 AM |
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quote:
Originally posted by Partofthechaos
It seems convention is to put the pump on the cold side of the rad, pulls from the rad and pushes into the engine. Then hot from the engine to top of
the rad, if the ECU controls the pump then no thermostat required. With that sorted, my next step is get get the flow rate correct.
Im not that familiar with electric pumps, are these to replace belt driven pumps or just boost them? If to replace surely having it thermostatically
controlled is irrelevant as the pump should work at all times, and the thermostat just decides when to feed the water through the rad when its up to
temp?
Mistral Motorsport
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CosKev3
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| posted on 29/11/22 at 10:11 AM |
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quote:
Originally posted by loggyboy
quote:
Originally posted by Partofthechaos
It seems convention is to put the pump on the cold side of the rad, pulls from the rad and pushes into the engine. Then hot from the engine to top of
the rad, if the ECU controls the pump then no thermostat required. With that sorted, my next step is get get the flow rate correct.
Im not that familiar with electric pumps, are these to replace belt driven pumps or just boost them? If to replace surely having it thermostatically
controlled is irrelevant as the pump should work at all times, and the thermostat just decides when to feed the water through the rad when its up to
temp?
You remove the original thermostat and run a pump controller,these vary the speed of the pump according to the temp of the coolant.
For instance my controller is set to only pulse the coolant until it gets up to the temperature I've set in the controller for warming up the
engine.
Then at the other end of the range once the pump is flat out the controller will then switch on the fan until the temp drops back to the set point in
controller.
These Jag V6s as standard have a stupidly complicated belt set up on the engine and the water pump is an external one so not built into the engine as
they run timing chains.
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loggyboy
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| posted on 29/11/22 at 10:29 AM |
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quote:
Originally posted by CosKev3
You remove the original thermostat and run a pump controller,these vary the speed of the pump according to the temp of the coolant.
Cheers for info 
Mistral Motorsport
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coyoteboy
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| posted on 30/11/22 at 04:11 PM |
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quote:
Originally posted by CosKev3
Big difference between the Davies Craig and Pierburg pumps is how they cope under a bit of pressure in the system,Davies Craig pumps performance drop
off a cliff with slight pressure in the system where as the Pierburg don't.
Can you explain the physics of how that would be the case? I'm interested how pressure would negatively affect flow in an incompressible fluid.
Did you mean "under stress" or were you specifically meaning pressure? Do you think the pressure increases seal friction or similar?
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CosKev3
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| posted on 30/11/22 at 09:53 PM |
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quote:
Originally posted by coyoteboy
quote:
Originally posted by CosKev3
Big difference between the Davies Craig and Pierburg pumps is how they cope under a bit of pressure in the system,Davies Craig pumps performance drop
off a cliff with slight pressure in the system where as the Pierburg don't.
Can you explain the physics of how that would be the case? I'm interested how pressure would negatively affect flow in an incompressible fluid.
Did you mean "under stress" or were you specifically meaning pressure? Do you think the pressure increases seal friction or similar?
I can't add pictures to this coal fired forum,but there is a pic in this link from Davies Craig that shows how pressure reduces the flow of the
pumps.
https://www.speedingparts.co.uk/p/engine-tuning/water-oil-system/electric-water-pump/davies-craig-ewp115l-electric-water-pump-kit.html
Similar charts are available for Pierburg pumps and they don't lose as much flow versus pressure as the Davies Craig do.
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lsdweb
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| posted on 1/12/22 at 05:30 PM |
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Some interesting info here - https://www.locostbuilders.co.uk/viewthread.php?tid=217777
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