If you look at some of the Toyota articles and similar, the efficiency is gained by electronically controlling the pump to run in a specific temp range for the engine to reach peak efficiency and emissions (closed loop).
It's really efficient to piggy back on the spinning motor to spin a pump wheel.
(Of course if you carry a lot of battery power with you charge at home, you can cheat a bit with an electric pump)
Probably the most fuel efficient way to go would be to change the water pump pulley size / build so that it pumps the minimum flow required at typical efficient driving.
Then add on electrical pumps to boost flow when needed (although creating the electronics to monitor and adjust this wouldn't be easy)
Quote:
Originally Posted by Daox
There are still other 'nice' benefits like having heat when the engine is off in winter, and cycling the pump while preheating with a block heater. But, if those are the only real benefits it really cuts down on the 'bang for the buck/time/pain in the butt' factor.  |