Reply to "Aluminum Water Pump Issue"

I'm coming in to this discussion late, but here are a few personal obeservations.....

No matter what people may think, increasing coolant flow in a well designed system will always help cooling....

Newton's law states Q = M * cp *dT or rewritten Q/M*cp = dT

Where Q is the heat load BTU/min., M is the mass flow rate of the coolant in BTU per pound per degree F, dT is the temperature drop through the radiator in degrees F. Thus if M the mass flow increases the dT (temperature drop) is larger.

What may happen in practice to cause poor cooling is the pump starts cavitating. More so in a Pantera where a) the tube under the car feeding the pump is smaller diameter than the pump inlet and b) has a 90 degree bend not far from the pump inlet. In a well designed system high radius bends and tubing of equal size would be used.

The radiator design is the largest restriction to going to very high coolant flows and it is suggested 6-8 ft/sec is optimal (do not exceed 10ft/sec)in a cooling system. Too high a velocity can result in aeration and foaming of the coolant, possible damage to the radiator by overpressure, cavitation of the pump due to excessive pressure drop through the radiator, and erosion of the radiator tubes.

To reduce cavitation one can...

Reduce pump speed - actually not so dumb, get one of those 30% higher volume pumps and use an underdrive pulley to slow it down 30% and your are back to stock volume with a pump running slower and less likely to cavitate.

FWIW some paddle style aftermarket pumps do have a backing plate on the paddles which helps reduce cavitation.

Switch to an aftermarket electric pump which has far less tendency to cavitate.

Increase suction pressure (reduce suction head) - Add a booster pump i.e. a remote electric pump after the radiator. Bear in mind the above 10ft/sec rule.

For my stroker that is half block filled I will go all electric or add the booster pump, probably the latter in my sitution and look at larger tubing.

Julian