NC hybrid setup/coolant blows heater core/how to avoid?

[Walter Sherwin]

>The pressure head which the water pump generates is proportional to the
>square of the pump rpm, and at , say, 5000 pump rpm, for a pump with an
>impeller the size of most water pumps, it would not be unreasonable to
>expect to see 25 or 30 psi of pressure in the water jackets in ADDITION the
>pressure from the radiator cap!! And if the thermostat restriction is
>removed, the water pump will cavitate due to not having enough NPSH at the
>resulting (higher flow at less developed head) point on its curve for that
>particular impeller speed!
>
>Regads, Greg
>




Greg,  what you say here is quite correct.   A couple of years ago, we
flogged a near stock BBC (with stock serpentine water pump) for several days
on a well equipped dyno.  One of the measured parameters was the post pump
water jacket pressure.  We were quite surprised to observe approximately
55psig of "head" (from a 15psig baseline) at 5000 engine RPM.  Post
examination of the data revealed the expected speed/pressure curve of a
generic  centrifugal pump.

Walt.