Underdrive pulley recommendations?

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Originally Posted by stephen wilson

I surprised that no manufacturer has gone to an electric water pump, with it's speed electronically controlled. There's lot's of power and efficiency to be gained, though I'm not sure it would ever be as reliable as a belt driven pump. (though Boxster water pumps haven't proved that reliable!)

I am not sure if any benefits would be found here. Having a mechanical WP that varies with engine speed is a good thing. Higher RPMs = higher heat = higher coolant velocity. Also electricity is not free. With an electric water pump, first you must convert mechanical energy to electrical energy with the alternator (maybe 20% loss) and then convert it back to mechanical energy at the pump (maybe another 20% loss). By this very rough calculation an electric pump would consume 40% more energy than a mechanical one for the same coolant velocity. The mechanical pump looks better to me. What am I missing?