Hi, we are designing a cooling system for some various size motors, 50, 40, and 30 hp motors and was wondering about the flow we should have for our water pump. I have been trying to locate information everywhere but have been limited to almost nothing. I was trying to get a base # of some stock OEM car flow rates but havn't been able to find any. I was thinking somewhere between the 5-10 GPM flow rate would be ideal. We want to use some standard automotive fluids for our system as well. If anyone has some other information/tips/calcs that would be great!The 65 HP engine we use pumps approx. 5 gallons per minute at full throttle.  The exact flow rate depends which radiator we are using, the number of elbows, fittings, length of hose, etc.  I should also add this is for a vehicle that is constantly on the move.   

The pressure drop vs. flow rate is very important not only for the pump, but for each component of your I just found this in a 2001 SAE paper on cooling systems:

Conventional cooling needs on smaller
engines with mechanically driven water pumps vary
between 2.0 to 2.6 L/min/kW. Some advanced engines
already run at 1.0 - 1.7 L/min/kW. It is predicted that with
an electric pump & diverter valve with precision cooling &
nucleate boiling sensing & control, flows under 1.0
L/min/kW would be achievable.
Pneumatic and electric  diaphragm pumps

2011-05-26

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