Electric water pumps for performance engines.

"Pump up the volume!"

In a performance engine you should never underestimate the need for adequate cooling.

All water cooled cars work on the principle of water being pumped around the engine and then to a radiator where it releases the heat.

Most hold the water in the engine until it warms up and then the water circulates to the radiator when the thermostatic valve opens.

Some manufacturers are fitting electric water pumps instead of mechanical ones and the after market fitting of  electric water pumps is taking off so what are the performance benefits of them?

Most water pumps are mechanical and run off the crank. 

This creates 2 drawbacks:-

Firstly water is pumped in proportion to the engine speed. So if you have been driving hard and then suddenly go slow the water is being pumped more slowly and the engine takes much longer to cool down.

Secondly the water pumps exert a pull on the crank. They are usually fairly bulky and take a fair amount of force to turn the impeller.

Power losses to the water pump alone have been recorded to be as high as 17 bhp on a 170bhp engine.


When you look at the benefits of electric water pumps you wonder why they are not fitted as standard to cars - but as always it often 'boils' down to cost!

Long used in Motorsport an electric water pump is able to address both of these issues. It must be noted that the extra current it draws will create pull on the alternator in a similar way to the air conditioning unit (but nowhere near as much!)

The electric water pump will come as a kit with the main pump and a controller. The more sophisticated controllers allow you to select an operating temperature for the engine from within the car.

The benefit of a water pump is that the water is circulated in direct proportion to temperature. The hotter the water then the faster it is pumped round the engine and this will assist with cooling. It also means that the pump is only running when it is actually required allowing the engine to warm up quickly and maintain an optimum operating temperature.

You will need to remove the existing water pump impeller and the thermostat as your electric water pump will replace these. Removal of the entire water pump is not absolutely necessary; indeed keeping the belt pulley in place will mean you do not have to get a new belt fitted.

A big benefit of an electric water pump is the fact that you can easily select the operating temperature of your car. Setting the temperature lower will mean the engine produces more power and setting it higher will improve the engines economy.

Sitting in traffic will no longer mean the engine reaches dangerous levels and the cooling fan on the radiator will have less work to do due to the faster cycling of the engine coolant around the engine.

Fitting an electric water pump is very straightforward, but as every car's cooling system varies we cannot give specifics here. The pump will usually fit inline near the switch that operates the flow through the radiator. You will typically have to cut a hose and fit the water pump inline and then wire this into the car's ignition circuit.

Depending upon your settings you could even let the water pump run when the car is stationary allowing it to continue to cool the engine when it is turned off.

Negative sides of electric water pumps.

Generally speaking an electric water pump will not last as long as a mechanical one. Many manufacturers recommend that the mechanical water pumps are replaced every 7 years or so anyway.

An electric water pump will also exert load on the battery, but this will not incur the same losses as the crank driven mechanical ones.

They can be difficult to fit and setup. Buying a kit designed for your car is strongly recommended. They are growing in popularity though and when setup correctly can really improve the running of a car.

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3 Responses to “Electric water pumps”

  1. fariba says:

    hi im fariba from iran. im an automobile engineering.already i have a project that is about electrical water pump . could you help me? i wanna know which type of veicle is approprite for EWP?(forexample is it good for trucks or city car or …) and is the type of motor important? ( forexample is it good just for electric and hybrid cars or no it can be good for diesel and petrol motor also? )
    i appreciate your help

  2. Peter says:

    Thanks for the helpful information, a quick question. As I keep blowing and splitting heater hoses and run a straight LPG turbo set-up so it gets hot quick also being a 3T Nissan Patrol the added weight and tires sizes all have a big play on temperatures, so my question is would it be best to just ad on an electronic water pump to the existing belt driven set-up or should I take it off and have the electronics do all the work? Also what minimum lph should a pump be to consider and lastly stainless or rated plastic??? Thanks..

  3. Francky says:

    I find the article very informative on Electric Water Pumps

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