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Tech Torque: What Is An Electric Water Pump?

Life sometimes gives us questions to ponder. Why is the sky blue, are The Rolling Stones a better band than The Beatles, should I have pineapple on a pizza, and what is an electric water pump?
Unlike the others, the answer to what is an electric water pump is surprisingly simple to divine.

An electric water pump, or EWP, is a mechanical device, powered by electricity, and pumps water. There. Sounds simple. But wait, there’s more. One immediate benefit of an EWP is in the name, the electric bit.

Because it utilizes that amazing and invisible power, an EWP isn’t reliant on the spinning of a crankshaft, the rise and fall of conrods, and the pulsing of injectors. They work as long as there is juice in the battery. This means that if a car or truck or bus has been running for a while and the ignition gets switched off, a control device can keep the EWP running afterwards. This is especially crucial in automotive high load areas or in motorsport.Consider a drift car, running a high revving petrol engine and fitted with a turbo. A talented driver can pound a drift car around a circuit and the engine will be constantly working hard. The driver gets to the end of their run and switches off. A mechanical water pump them immediately stops working. This means cooling fluid is no longer pushed through the engine internals and through the radiator. This can lead to severe damage to the engine and potentially the radiator as well.

Another benefit of an EWP is the constant pressure and flow rate. An easy comparison is a child’s toy fan. Blow gently upon the vanes and it’ll spin slowly. Give it a good huff and it’ll spin hard before winding down. That’s a mechanical water pump, rising and falling with engine revolutions.

An EWP suffers not from this, and EWPs from an Australian company called Davies, Craig, with flow rates of up to 150 litres per minute, will CONSTANTLY deliver flow, as they’re not dependent on a crankshaft and belt to spin. And because they’re electrically powered they’re not sapping energy from a mechanical system. This means less strain, better fuel economy, and longer lasting mechanical parts. And they’re a lot smaller, which means less weight, better efficiency, and can be mounted in certain positions to help tidy up an engine bay. Digital controllers can assist here. These allow fine tuning of how an EWP works, including running a pump after a car’s engine has been switched off.Along with moving a cooling fluid through a radiator and engine, moving air across the vanes of a radiator, or heat exchanger, is crucial to keeping an engine as cool as possible.
Cars come with a belt driven fan, and those belts are attached to pulleys which are attached to the engine. Quite a few designs have a mechanically driven fan attached to the nose of the mechanically driven water pump. The fan has a kind of clutch that allows the fan to spin up to speed or spin down to a stop by itself.

In a cooling sense, these fans are only effective if the engine is running. And due to their source of power, they’ll not be as energy or fuel efficient, plus they’ll sometimes not be as aerodynamically efficient due to the design of the fan blade, their location in respect to the radiator, or lacking a shroud to assist in directing airflow. When it comes to electric fans for cars, or thermatic fans, there’s a different range of possibilities to explore. Because they’re powered by the vehicle’s electrical system, they’re far more energy or fuel efficient. A digital controller can be fitted to allow the fan to be on all of the time, only when needed, or to run after an engine is powered off.

A driver can choose to fit one fan or, two fans, and in an upstream (ahead of the radiator) and/or downstream (between the radiator and engine) configuration. If going for a two fan, upstream/downstream configuration, it’s recommended to have one fan on one side of the radiator (left or right) and the other in the opposing side. Let’s say one fan is on the engine’s side and mounted ahead of the driver, therefore the other would be on the headlights’ side and ahead of the passenger.

When it comes to finding and fitting the right electric fan or fans to suit your particular car, there are a couple of areas to look at. The thickness of the radiator is the first point of call. This is due to the amount of airflow required to pull or push air through the vanes. Then there is the shape of the radiator itself. As a rule, one large electric fan will do as good, or a better, job than two smaller ones. However, a wider than taller radiator may negate a single fan fitment, therefore two smaller diameter fans can be mounted side by side. It’s here that the research teams have provided a different solution. Davies, Craig electric fans for cars are built to have reversible blades and hubs.

When it comes to the design of the blades themselves, these are shaped to be both more aerodynamically efficient (reducing drag) and less likely to vibrate and cause supersonic shock. This is literally where the ends of the blades reach a velocity approaching the speed of sound, and therefore, not unlike many WW2 fighter planes that crashed due to the phenomenon not being understood, shake uncontrollably.The blade design A Davies, Craig uses has them straight out from the hub, and by curving the struts that are inside the shroud housing, airflow is increased and airflow noise is decreased. Also, when it comes to the tips of the blades, we’ve looked at the aerospace industry and the work put into the winglets on the ends of the wings on aircraft. Those stubby little winglets decrease air turbulence and balance air pressure as the tips rotate past the shroud. And because not every engine is the same, Davies, Craig offers six different fan diameters, from 8 inches to a whopping 16 inches. This means that there will be one or two electric fans, at least, that will be ideal for your engine and radiator size. Couple these with their extensive range of digital controllers and there is a package that will do a lot to be far better than an existing mechanically driven package.

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