Cool running

Automotive manufacturers are racing to be first to market with an electric water pump for cooling systems that promises to liberate extra power, improve fuel consumption and prolong engine life.

Small Australian supplier Davies Craig appears to have stolen a march on tier-one suppliers by patenting a system which uses an electronic controller to vary pump speed in response to engine temperature.

Currently car water pumps are driven from the engine by the same belt as the alternator. They are designed to provide enough cooling for when the car is stationary and idling, but at higher speeds the flow of coolant is much greater than needed. Davies Craig managing director Richard Davies said its research found the optimum flow was 80 litres/minute, beyond which increased flow provided little extra benefit.

A typical water pump, on a 3.9 litre V6 engine used in the Australian market created a flow of up to 250 litres/min. At 5,000rpm it absorbed up to 10kW (13bhp) of power. Davies Craig’s EWP electric water pump uses less than 0.5kW, resulting in a noticeable increase in power and torque. The pump is already available on the aftermarket and has proved popular in motorsport as a cheap way of gaining extra horsepower.

However, the big players are more interested in the potential 3-4 per cent improvement in fuel efficiency. In May the firm will launch its third generation pump, modified to suit car makers, and said it is working on applications with 12 manufacturers. Improvements include a long-life ceramic pump shaft seal and an increase in flow to 110 litres/min.

Davies says the pump will help makers achieve Euro IV emission standards because controlling the temperature allows engines to run hotter, improving efficiency.

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