FYI, 20hp is certainly not anywhere what a typical commuter car on a typical commute would gain. Their biggest pump only draws 150 watts which is about 1/5 HP.
Actually an engine driven water (and oil) pump makes a lot of sense. It's a low loss transmission of energy to the pump and they only need to be turning when the engine is working anyway. More oils and water is also usually needed at higher rpms too.
Power steering pumps and AC pumps on the other hand do not have this serindiptuous relationship with RPM. Of course eliminating these entirely is a step towards better gas savings, but some efficiencies can be had by not turning them in direct proportion to the engine rpm. One of the ways to do that is with an electric motor.
It is much more "lossy" to turn the alternator to turn a motor to turn the pump than it is to just turn the pump, so with power steering it is more efficient to eliminate the hydraulic system and have an electric assist.
AC, I dunno, peltier junctions v/s motor driven compressor I recon, I think I read about a wobble plate arrangement around here recently also.
If you get the kit that has the variable speed pump/controler, then I could see how it would be rather affective, I wouldn't want to compleatly turn off the water pump, because of how the temp sensers are not alwas located in an area that has coolent naturaly flowing past them.
the biggest advantage of course with an electric water pump is going to be with engines that run at higher speeds, like in racing conditions.
The thing I'm wondering is: with all the added electronics to the car, wouldn't you need a higher amp Alternator (depending upon model of car) and therefore wouldn't that produce more load on the motor? I guess one would have to sit and crunch some numbers given the nominal amp draw on said devices.
Wow... I wish I had known about this pump when I was still working on the FrakenCivic. It definately would have been a fun project (and would have saved me the hassle of making sure the crank pulley was the correct one for the power steering pump).
What about the efficiency of the alternator and electric motor? With a current water pump you motor is turning a pump. With an electirc you are turnning the alternator with maybe 90% efficiency then running an electric motor with maybe 90% efficiency.
The only way I see it being a gain is if you could run the pump at a lower output (this pump claims this) or turn it off when not needed.