water pump restrictions

[charles \(chuck\) r botts]

Water pump flow is designed to provide maximum cooling capacity near
maximum torque/energy. At higher rpm, that same pump would require a lot
more hp to drive it so the pump is also designed to be very inefficient
[lots of internal slippage] at higher differential pressures. That design
feature reduces the power needed to drive the belt driven water pump at
higher rpm. It was a common thing to do in my old sports car racing days
to put a restriction in the pump outlet to decrease the hp needed to
drive the pump [make it even more inefficient] at high rpm and thus
increase the hp available at those higher rpm. Often, the engines were
modified to operate at even higher rpms than stock and still used stock
water pumps. It had nothing to do with better cooling.

High constant cooling needs such as long pulls up steep hills at high
altitudes or high speed runs across the high desert with the A/C on were
not a consideration.

 

[thomas g. warner]

Haven't gone back and read my engineering books but intuitively I think that
putting a restrictor in the outlet of the water pump would increase the HP
needed to push fluid through the sytem, ie; increasing the friction in the
system. The only way to reduce the HP used by the water pump would be to
change the pully sizes that drive it and lowering the RPM of the pump at a
given engine speed.

All the restictor is going to accomplish is reducing the flow thru the radiator.

>Water pump flow is designed to provide maximum cooling capacity near
>maximum torque/energy. At higher rpm, that same pump would require a lot
>more hp to drive it so the pump is also designed to be very inefficient
>[lots of internal slippage] at higher differential pressures. That design
>feature reduces the power needed to drive the belt driven water pump at
>higher rpm. It was a common thing to do in my old sports car racing days
>to put a restriction in the pump outlet to decrease the hp needed to
>drive the pump [make it even more inefficient] at high rpm and thus
>increase the hp available at those higher rpm. Often, the engines were
>modified to operate at even higher rpms than stock and still used stock
>water pumps. It had nothing to do with better cooling.
>
>High constant cooling needs such as long pulls up steep hills at high
>altitudes or high speed runs across the high desert with the A/C on were
>not a consideration.
>
>