Water Pump Flow Rates

[Gerald Morris]

The actual flow rate is throttled by the thermostat.
.....

THIS is the greatest controllable variable we have aside from pump capacity for determining flow rate. A Word to the Wise from this is to be SURE and RETAIN some thermostatic control. I once pulled the thermostat on a 1955 Chevy Apache L6-296 engine during the most miserable summer of my life on the advice of an "elder" TO NO GOOD END. Why? NO CONTROL! That motor took a good half hour to warm up, assuring MUCH WASTED PETROL on short trips.

The rate of heat transfer is proportional to the difference in temperature. (This can be shown from @Gerald Morris formula above. All other variables held constant, the rate of heat transfer Q is proportional to the temperature difference T2-T1.) ....

All combustion engines work best when the delta T is LARGE, as this assures that one then can have a HIGH POWER REACTION in the region of combustion. One must convey the exhaust heat away rapidly when so doing. Power after all is the measure of delta Q over delta t, (Joules/second --> Watts) which we aspire to translate mechanically into Newton * meters/second, where we rapidly accelerate, then simply work against sundry frictions of the road to maintain constant velocity. Thin cylinder walls help convey the heat away quickly, at the risk of rupture, et cetera.

To optimize cooling then really comes to flow rate, and finding the time it takes to remove exhaust heat. MUCH of this is linear, but I suspect not ALL of it. I'll look into this if I get the time, and let y'all know if I find any higher order stuff to optimize for.

 

[Cazman]

so.. which pump should I buy for my 440 to still look stock and have a decent shot at cooling?

 

[Gerald Morris]

The Gates pump looks almost identical to the "with AC" pump Mopar equipped the circa 1970 engines with. I like it. It gives good flow for a modest price, but doesn't move your coolant so rapidly that it doesn't have time to either absorb heat from the cylinders & heads, or exhaust that heat in your radiator.

Mind you, the thermostat arbitrates flow to a good extent. Having just replaced the timing chain in Mathilda's 383, I wound up re-installing the Gates pump and Stant "Superstat" I have been happy with for about 19 months for the sake of expediency. I can watch the temperature rise, then rapidly fall a good 35 degrees Fahrenheit when the thermostat FIRST opens, admitting COLD coolant from the Cold Case MOP-753A radiator. Then the thermostat closes, after the engine coolant temperature drops from 205 F to 170F in the course of a minute. It then will warm back up to about 195, at which point the thermostat opens again, admitting another "sip" of not quite so cold coolant to the engine's coolant jacket, dropping to about 190 F, where the engine normally runs. During the day, with ambient air temperature in the mid 50s, this oscillation occurs just as I've described it, with 2 cycles of thermostatic operation to get the coolant mixture to the 190 F which the 180 F rated thermostats I've used for this 383 settle to. On COLD nights, with freezing or sub-freezing temperature, the thermostat might oscillate more often, especially if I hit a highway, where increased engine heat must be balanced by frigid coolant from an excellent radiator cooling things at highway speed.

I haven't run the pusher fan since November.

So, get a Gates pump. If the rest of your cooling system is in good working order, you will have a well cooled 440 which will operate at decent thermodynamic efficiency (for these engines) for some years. I keep a CLOSE WATCH on engine temperature every time I run that 383, and advise you to do likewise. Even if your idiot lights work, get a reliable scaled gauge.

 

[Cazman]

Ok. You’ve sold me. Thanks.