Why The Power The EWP® Uses Is Much Less Than The Mechanical Pump.

12/09/2019 12:00AM

The EWP® is designed for maximum efficiency at its maximum speed of 2250 rpm. Being in nylon, the impeller can have aerofoil cross section with associated lift, and the tip clearances can be very small. The mechanical pump has to run at 600 rpm and 6,000 rpm and it cannot be efficient at both those speeds and all speeds in between. At 600 rpm a mechanical pump typically moves about 15 l/min, and at 6,000 rpm 150 l/min. The high flow rate is there not because it is needed but because it has to be accepted if a flow rate of 15 l/min is needed at idle. Furthermore, as the power the pump takes increases as the cube of the speed - when the mechanical pump is operating at the higher speeds, as it does as an engine passes through its gears, it is taking power of the order of 8 to 15 kW. The EWP® which uses at maximum speed, 9 amps x 13 volts gives 120 watts at say 30% efficiency from the alternator to hydraulic power means about 0.4 kW to drive the EWP®, when it is operating at full speed which is usually less than 20% of racing time.



In addition, with the old mechanical pump and a thermostat set up, the thermostat is partly closed most of the motoring time and in a cool climate at highway cruising, it is always about 90% closed. As a consequence, the flow and pressure being generated by the mechanical belt-driven pump and paid for with power and torque, are choked at the thermostat and wasted. This system has worked reasonably well for a long time but it is not smart. With your EWP® and digital Controller, power and torque is never wasted as there is no choking (no thermostat) and only as much flow and pressure as is required is produced.

We are starting to see the allowance of EWPs® in formula racing mostly to prolong the life of engines with the run on after hot shut down to eliminate heat soak. In any case, we cannot stop progress, the use of drum brakes or cross-ply tyres seem to be decreasing in racing runs.