Bringing Engine Cooling Into The 21st Century With Davies Craig

While there have been many innovations in the design of most cooling system components over the years, they still rely on mostly old principles. We have been searching for a way to upgrade the cooling system on Project Rehab, our street/strip Fox body Mustang. We found a way to not only do that upgrade but also save weight, gain horsepower, and bring the cooling system into the 21st century with help from Davies Craig and their USA sales and marketing ambassadors 3P Connect.

Davies Craig sent us their EWP 150 water pump, two 12-inch thermatic fans, and their EWP and Fan Digital Controller for our installation.

The Old Pump

A mechanical pump can’t be designed to operate efficiently or ideally under all circumstances. Josh Backes, 3P Connect

The water pump is driven either off a belt run by the crankshaft, or off the timing belt or chain in some applications. The pump requires mechanical energy from the crank to operate. Innovations in pump design through the years have improved the efficiency however, the primary principle has remained the same.

Since it relies on engine RPM to circulate coolant the engine driven water pump operates counter to what demand typically dictates. At idle when there’s no air being forced across the radiator by the vehicle in motion the water pump is also circulating extremely slow leading to heat soak and higher engine temperatures. At speed when airflow helps tremendously with cooling, the pump is often moving more coolant than it needs to. “A mechanical pump can’t be designed to operate efficiently or ideally under all circumstances,” says 3P Connect’s Josh Backes.

Engine driven water pumps are dependent on RPM not temperature demands for flow which is counter to what your engine typically needs. They also require mechanical energy from the crankshaft to operate.

Ball of Wax

Since its design and patent in the late 1930s by Sergius Vernet the mechanical thermostat has changed very little. Essentially the thermostat in your car’s engine operates using a wax plug and spring. When the encased wax begins to melt its increasing volume pushes open the valve for the thermostat allowing coolant to flow to the radiator. As the engine cools down the wax begins to solidify closing the valve in the thermostat. It’s a simple principle that has remained mostly unchanged for over 70 years.

Left: One of the first pieces to go is our mechanical thermostat. Right: Temperature will now be monitored and controlled by the Davies Craig EWP and Fan Digital Controller.

Modern Approach

Davies Craig has been in the automotive cooling business for 40 years. Developing cooling systems in their home country of Australia, DC has brought their technology to the US market and it is taking hold with enthusiasts.

Davies Craig sent us one of their EWP 150 alloy water pump and Digital Controller kits, part number 8070, to replace our stock mechanical water pump and thermostat with a microprocessor controlled electronic unit. Additionally they also sent us a pair of electric fans which will take the place of the engine driven clutch fan on our 302.

EWP 150

Capable of flowing 40 gallons per minute the EWP 150 is a lightweight high flow water pump that mounts in our lower radiator hose.

The EWP 150 is an electric water pump unlike something most enthusiasts have seen before. The housing design resembles that of a centrifugal supercharger or turbocharger. The aluminum alloy unit weighs just two-and-a-half pounds and is capable of flowing 40 gallons per minute (150 liters per minute). This unit can completely replace the stock mechanical water pump and act as the sole coolant circulation method, or it can be used as a supplemental, booster pump to assist the water pump in moving more coolant when engine temperatures dictate the need. “When you bring an electric pump into the equation you can benefit from the high output that you need at idle, but also control the volume of the pump throughout the entire RPM spectrum when used with our controller,” says Backes.

Top Row: After getting our radiator out of the way we pulled the power steering pump and alternator off the car. We’ll be eliminating the power steering system in a future article so we did not reinstall our PS pump at this time. With the accessories out of the way we removed our water pump and put it in a vise. Bottom Row: Left and Center: We used a cut-off wheel to remove the impeller from the water pump shaft. This will allow the water pump pulley to act as an idler for our belt and the mechanical pump housing to still be used for mounting our alternator. Right: Our old timing cover was damaged long ago causing oil and coolant leaks. We sourced a used replacement from the local machine shop.

The design of the pump allows it to be mounted in the lower radiator hose. This has several additional benefits. The first is that it keeps the pump’s electric motor from becoming heat soaked by radiant engine heat preventing premature wear on the electric motor or degraded performance from high heat exposure. Mounting it to a hose with no other connections to the engine or frame also isolates the pump from vibration further prolonging its life.

The EWP 150 can be controlled via the Davies Craig EWP and Fan Digital Controller, or in vehicles that see extreme use (such as road racing or open track) it can be wired to run constantly when the ignition is on.

With our mechanical water pump housing back on we modified our lower radiator hose to accept the EWP 150. This was done by cutting a bend out of the lower hose, that bend was then replaced with the EWP 150 which makes the turn for the hose.

The EWP 150 mounted in our lower radiator hose.

Smarter Coolant Control

The brains of our cooling system upgrade is the EWP and Fan Digital Controller. This controller takes the place of there thermostat and controls both the operation of our EWP 150 water pump as well as our dual electric fans. “When you combine the Digital Controller with our fans and water pump, you’re controlling those components based on temperature and not engine RPM,” says Backes. “We’ve come a long way since the invention of the thermostat, it’s time to bring your cooling system into the 21st century.”

We mounted the Digital Controller to our center transmission hump in front of the shifter. This will allow us to easily monitor operation of the system.

Bleeding The System

Filling and bleeding a cooling system to remove all the trapped air can be tricky as you wait for the thermostat to open and fluid to drop in the radiator in traditional setups. With the Davies Craig EWP you can hot wire the pump to continually run until you have circulated all of the fluid in the system. This makes refilling after repairs, maintenance, or modifications easier than ever, and ensures there’s not a pesky air pocket hiding in your cooling system. We used two female spade terminals and some scrap wire to make a harness allowing us to run the pump continually for the bleeding process.

The controller monitors engine temperature via an included temperature switch which is mounted in the upper radiator hose. It has a programmable temperature point adjustable from 165º F to 205º F.

Since the EWP 150 can circulate a large amount of water quickly, the controller cycles the pump on for 10 seconds and off for 30 seconds when coolant temperature is low. This allows coolant to circulate throughout the engine during warm up. As the coolant temperature gets nearer to the set point the controller then begins cycling the EWP 150 more rapidly at a rate of 10 seconds on and 10 seconds off. Once the temperature reaches 5.4º above the set point the system will run the fans and the EWP 150 constantly and then return to an appropriate cycling once the engine is cooled.

This method of cycling the water pump allows for extremely lower amperage and voltage draw. “This is especially useful with older vehicles where the charging system may not be up to date. By cycling the pump you reduce the demand on the electrical system significantly. The max you’re going to pull with our pump is 10 amps, but with our controller it averages between six and seven amps,” says Backes.  Since the Digital Controller is also mounted inside the vehicle cabin it can also be used to monitor system operation. The LED lights for Fan and EWP will flash or illuminate steadily depending on the system’s status.

Big Fans

Completing our cooling system are a pair of Davies Craig 12-inch thermatic fans, part number DSCL 0062. Capable of flowing 800 cfm each, these fans will move plenty of air across our radiator when switched on by the Digital Controller. At just 3.2 pounds each they weigh in at less than our stock clutch fan as well. Included with our fans are the appropriate relays and fuses.

Left and Center Left: We cut our dual fan bracket to the appropriate length and mounted it in front of the radiator. We secured this to the upper radiator support using 5/16-inch nuts and bolts we had picked up at the hardware store. The bracket and fans were mounted so that the fans sit directly against the radiator. Center Right: We mounted the fan relays to the passenger side inner fender. Right: Modifying the upper radiator hose was next. We cut the upper hose in a straight section in order to install our temperature sensor. The connections for the temperature sensor and EWP are easily made using the supplied harness connectors.

When you combine the Digital Controller with our fans and water pump you’re controlling those components based on temperature and not engine RPM.

While many big electric fans draw a large amount of current, these draw only nine amps each on a 12-volt system, the included fuses are just 15 amp units. This is in stark contrast to what we’re accustomed to with cooling fans which in some cases can draw over 30 amps. “We’ve been building cooling systems in Australia for over 40 years, so we’ve had plenty of time to trim the fat and get the fans very efficient as well as the pump,” says Backes. This is ideal for our old Fox body which still wears an original 65 amp alternator.


We installed our entire cooling system upgrade in one day. Since we’re completely eliminating the mechanical water pump from our system we needed to make sure it wouldn’t restrict coolant flow, but would still remain in place since Ford designed the pump as part of the mounting system for accessories like the alternator, power steering, and air conditioning. We’ve outlined the installation in photos here and it’s a fairly straight forward process. The biggest part of this installation is modifying the mechanical water pump by removing the impeller. This prevents the impeller from acting as a restriction in the path of the coolant.

With everything in place all that’s left to do is tension our belt. The water pump pulley now acts as an idler.

Davies Craig has installation kits available for small-block Chevy engines that completely eliminate the mechanical pump. They’re working on a similar solution for small-block Ford engines as well as LS platform engines. Davies Craig provides detailed wiring instructions for the Digital Controller and fans. We wired our fan relays with the hot wires for the relays connected to 12 volts power under the hood.  The controller requires key on power, which we got from our Ron Francis Wiring Express panel. Constant power and ground came from the battery.


With our system bled and full we cycled our key on and programmed the digital controller. This is simple one button operation. The controller will continue to cycle the pump and fans for two minutes after the engine is shut off, or until the temperature drops below the programmed temperature setting. This makes it ideal for racers who drive to the track or participate in True Street style events where driving the car is a requirement. “This helps reduce heat soak by continuing to circulate coolant through the radiator and cool it with the fans, that’s something you can’t do with a mechanical pump,” says Backes.

Our final steps involved filling and bleeding our cooling system and programming the Digital Controller.

We can see a wide variety of uses for the Davies Craig system. Everything from cars like our Project Rehab, to daily drivers, classics, pro touring machines, race cars, and even tow rigs. In eight decades there have been too many advancements in automotive technology for us to begin to count. The Davies Craig system is a much needed advancement resulting in a smarter, modern cooling system alternative to today’s enthusiasts.

About the author

Don Creason

Don Creason is an automotive journalist with passions that lie from everything classic, all the way to modern muscle. Experienced tech writer, and all around car aficionado, Don's love for both cars and writing makes him the perfect addition to the Power Automedia team of experts.
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