electric water pump on the street

[sen2two]

Originally Posted by Mazdabater

Correct me if I'm wrong but isnt the main point of an ewp to keep the flow constant at its most efficient point? As opposed to a belt driven pump that varies at rpm, I would have thought it would be better on the street as your pumping more fluid at idle.

Not really. Its to reduce friction on the crank to gain more a few more HP. Especially in the top end of NA cars.

[Pete_89T2]

^These are both valid advantages for an E-water pump. Being able to control flow rate independent of RPM helps to optimize the efficiency of the cooling system, all other things being the same, and switching to an EWP should get you a net reduction in parasitic loads at the crank. I say "net reduction" because the electrical power needed to run an EWP isn't free - the alternator will have to work harder (more drag on the crank) to produce that power. The question is does the increase in parasitic drag from the alternator get offset by a larger decrease in parasitic drag from the mechanical water pump?

[My5ABaby]

Originally Posted by Pete_89T2

^These are both valid advantages for an E-water pump. Being able to control flow rate independent of RPM helps to optimize the efficiency of the cooling system, all other things being the same, and switching to an EWP should get you a net reduction in parasitic loads at the crank. I say "net reduction" because the electrical power needed to run an EWP isn't free - the alternator will have to work harder (more drag on the crank) to produce that power. The question is does the increase in parasitic drag from the alternator get offset by a larger decrease in parasitic drag from the mechanical water pump?

And to expand on it, is the offset even worth it?