Electric water pump and digital controller question

Does anyone have experience (good, bad, so-so) with the Davies, Craig electric water pumps and digital controllers? Specifically, Davies, Craig has recommended the EWP150 pump (150 lpm/40gpm) pump along with their digital EWP/fan controller ( https://daviescraig.com/product/ewp...pm-remote-electric-water-pump-controller-8970 ) for my mid-engine, front radiator Miura project car that is using a 5.0L Coyote motor. This setup doesn't use a thermostat as the digital controller varies the EWP speed to control the engine temp for whatever setting you program into it.

In concept, this all sounds great to me and better than other EWP that run at full speed all the time and use a thermostat to control temperatures. But there's nothing like first hand experience to show if something actually works good for real. Has anybody here used one of these setups?

Brian Stewart
I have one in my GT40. It has worked extremely well, even in very hot weather and stop/start driving. However, things went a bit haywire a few months ago when water got into the system during a torrential rain event. This resulted in the pump and fans running full-on most of the time, which eventually drained the battery (75 amp alternator could not keep up). Possibly my fault as the instructions clearly state that the controller should be installed inside the cabin away from water and excessive heat (mine was mounted low down on the bulkhead behind the drivers seat in the gap behind the inspection panel). Am in the process of installing a new controller, which should be up and running again within a week or so. Will let you know how it all goes.
Useful and timely thread. I am also about to embark on the same route with my build using a 302. Good info on the location of the controller, that makes sense. Is there an ideal place for the pump? Front of car or near the engine or doesn't it matter? I was sort of assuming the latter and just going to put it where I can find space, probably near the motor.

I’ve used the EWP150 pump on my ’40 for the last 10,000 miles with no major issues. I did originally use the EWP130, which had the plastic body and had an early failure, but the replacement has coped without issues on to multiple trips to Spa & LeMans (35+ degC and sitting in heavy traffic) and track work. I haven’t used their controller; it runs all the time the ignition is on.

However, going forward on the next build I’m doing (MDA GT40), I’m using an OEM pump from Pierburg, the CWA200, which flows 116Ltr/min at 7psi. Whilst the Davies, Craig pumps states it flows 150 lpm/40gpm, this is at 0psi, which not a representative test condition.

Also, these Pierburg pumps are used in there thousands on BMW 3, 5 & X5 engines as well as other applications, which result they are more robust design and have followed a production validation procedure. They do require a PWM signal to control them, but stand-alone controllers are available, or aftermarket ECU’s generally provide a PWM control signal. This allows the flow to be set against the coolant temp




  • Description_CWA200 PWM.pdf
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I looked at the Davies Craig for my SL-C, but I decided to go with a Pierburg. They were the world's first series-production supplier of an electric coolant pump so they've been doing it longer than anyone. I also know that it’s been used by multiple SL-C endurance teams and several GT2 teams. The pumps are manufactured in Germany and are OEM equipment for BMW and others. While the race credentials are nice to have, the proven OEM applications which are more applicable to my use case.

Pierburg pump have a brushless motor and an integrated variable speed controller which can be controlled via a PWM signal. Tecmotive (Tecomotive - tinyCWA) makes a really nice ECU to drive everything. It’s looks small compared to the Davies Craig one.

There are lots of Chinese fakes, so make sure you get the real thing. Below are a couple of relevant links to my build thread.

S2's Build Thread | Page 22 | GT40s

S2's Build Thread | Page 22 | GT40s

You can also weld a manifold to the aluminum cap;

water_pump 01.jpg


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I am not familiar with the Pierburg design, but the Davies Craig pump is a 'flow through', this allows it to be used in conjunction with a standard mechanical pump as a booster pump and only supplement cooling when required via PWM controlled coolant temperature input.

Glenn M

I've used the DC 150 (cast alloy) and the electronic controller from the start and thoroughly recommend them. Mine is in the front of the car and I removed the mechanical one and the thermostat. As Andy says, what is the point in keeping the mechanical one? I like the fact that when motoring along and things are cool, the pump is just pulsing, yet when in traffic on a hot day, it is flat out, earning it's keep - the complete opposite of the mechanical one.
Great information, thanks guys. I plan to use an 8 stack EFI in my Miura with a Holley ECU. Holley ECU is for the Coyote variable cam timing. Does anyone know if the Holley ECU can act as the controller for EWP itself?

Related question. For those that are using an electric water pump, do you also have a heater unit in the car? If so, do you get adequate hot coolant flow to the heater core from a single EWP to get good heat out? I ask as Davies, Craig recommended that I use a second, smaller booster pump for the heater circuit/lines. They recommended this second pump be wired to the heater switch such that it only comes on when the heater is turned on.

I think part of the second pump recommendation also has to do with pump locations. Pumps push coolant a lot better than they draw/suck coolant. So the recommended location for the main EWP is near the radiator so it can push the coolant to the engine. Likewise for the heater circuit, the recommendation is to locate the pump near the engine so it can push the hot coolant the 8 feet or so to the heater core.

Glenn M

Personally, I don't have a heater and have never found the lack of one a problem.

As for the placement of the pump re. pushing/sucking, surely it is a circular system, and it makes no difference where you put it? Wherever you put it, it is pushing one half and sucking the other?

Howard Jones

The best place to put the pump outlet is directly at the cold return to engine ports. This would be the return side of the mechanical pump if it was on the car. Why? Because you want the highest system pressure right at the inlet to the engine (hottest spot). Putting it there is the same place that the mechanical pump is located.

I have a DC150 and controller in my SLC and it does work. 100F COTA with track temp +140F. The engine is 450HP SBC and is run 3000-6500 for 30 min sessions with full power on both +140mph straights. I have set the controller to 191F and it shows full-on with its temp sensor showing 198-205F.
My water temp gauge is showing 200F. That's fine.

If I were to add a second pump, I would use a Steward inline and place it at the radiator inlet side. This would place one pump at the engine inlet and one pump at the radiator inlet effectively dividing the system into two sections. I think this is the optimal configuration if one pump is marginally effective.

Place temp sensor(s) in the top of the intake manifold or at the point of max coolant temp not in the radiator. Do not run thermostats or restrictors in their place.

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I assume that just about any ECU can control the pump via PWM. The bigger issue is the required logic especially if you're not going to run a thermostat. Also keep in mind that a mid-engine car has a much longer cooling circuit so that needs to be taken into account. You can read the doc for the Tecnomotive ECU that I linked above to get all of the configuration settings that they support. If the Holly doesn't have a built in feature or an available template it's going to cost you a lot more than the $190 for the Tecnomotive ECU.

You can pump before or after the engine. I have a 1000HP supercharged LS7 and it was strongly recommended that I put the pump before the engine to ensure that enough pressure reaches the rear cylinders -- apparently cylinders 7 & 8 can become an issue with that engine. I'm not running a thermostat, but my plumbing accommodates adding one if I have to.

Water is going to take the path of least resistance which takes a lot of things into account. Number/type of bends, length, core resistance, etc. I've seen some people tap the heater line at 90 degrees from the flow... so that never has a chance of working well. I tapped the heater after the engine and I return it immediately before the pump. I assume that circuit has less resistance than the radiator loop, but time will tell if it works right... which is why I have considered were to add a heater pump if I need one;-)
Yes i have the EWP150 and digital controller. It works extremely well, very efficient. I also bought the water pump blanking plate/casting that they sell for the windsor engine which made it very neat. Not sure if they do a coyote one but worth checking. At first i did without a digital controller but i found it was too efficient and difficult to warm up. I fitted the controller and its been excellent.

Howard Jones

I talked to a Steward engineer about mechanical pumps for my GT40 years ago and he was very helpful in explaining the problems a mid-engine layout presents. It's not only the length of the system but the number of turns. He told me that every 90 was the equivalent of adding 4-6 FEET of length. Use two 45s with a short length of straight between them if possible to allow turbulence to subside and flow reattach to the tubing walls.

He told me that they would recommend two pumps as I described above in a mid-engine layout and in fact, many IMSA prototypes do it like this.

If you make it from stainless tubing you MUST back gas the system when you weld it up. If you don't the deposits inside the tubing at each weld joint will cause a huge amount of turbulence and reduce the efficiency of the system.

Heater: I would not use one until the car is running and you have sorted the cooling system. Run a short length of hose between the heater ports at first. The heater system can be a great place to trap air.

Also, place the electric pump as low in the car as possible to increase inlet head. Think of a dam and a hydro plant turbine. All that water up above the turbine (pump) inlet increases pressure and reduces the possibility of cavitation on the pump impeller. This is the main problem with a mechanical pump up on the front of the motor. Much of the system coolant volume is BELOW the pump inlet. The ability to place the pump low in the car below the coolant volume is the primary reason they work so well. The fact that they can be run at an rpm that suits the impeller design is the other major factor in their success.

Don't forget to design in a steam/air vent system to bleed air from the system and return it to the header tank.
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Howard Jones

This is the Meziere I would use if I bought one myself. The 25Hrs of Thunderhill NASA SLC used one I believe.

I should reiterate the points I was making above. Electric pumps have two very important advantages.

First, they can be run at a constant impeller speed that best suits the impeller design. This is a huge improvement over a mechanical pump run at the engine speed whose speed drops far below the optimal impeller speed at idle and slow cruise speeds and is spun far faster than the impeller is designed for causing cavitation at high redline engine speeds. So what do we do? We try and find a compromise pully ratio that works over the full rev range. This is very hard to do for a dual-use car (street and track).

Second, I cannot say it strongly enough. The pump impeller input location in relation to the coolant system height is very important. The standard location of a V8 in a front-engine application and its front-mounted mechanical water pump is a compromise at best. This configuration at least does not suffer from the extreme length of the cooling system in a mid-engined car and is designed for street driven cars and moderate engine rev ranges along with low average thermal loads.

When you add the elements of a low radiator and very long and low side pod tubing with several bends (3 or 4 nearly double the effective system tubing length and we are using that many on each side!) in them you begin to reach a point where everything is working against you.
Then if you place the pump a foot higher than necessary on the front of the engine you have just about made the perfect storm when it comes to a cooling system design. I would guess 80% of the coolant volume is below the pump inlet and the system length approaches 30-35 feet long!

That is completely wrong! The water needs to be above the pump!!!! The transit tubing from the pump to the radiator needs to as straight and short as possible, and the water pump needs to be run at the design speed of the impeller. AND you have to get the air out and keep it out!

No, don't replace the mechanical pump with an electric one in the standard front of the engine location. It really makes no sense.....................

Suffice to say every detail needs to be optimized.
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