Joined: Sat Aug 19 2006, 05:03PM
Location: Ontario, Canada
Posts: 2919
If you scroll halfway down the thread that I've linked to, someone has done a controlled study of flow rates for various bigblock water pumps. Very interesting!
My stroker is running a cast iron WP housing with a CAT aluminum waterpump that looks like the Edelbrock one in their test #2. The flow numbers of that pump are pretty lousy below 2000 RPM. Maybe I'll try to find a different WP for next summer and see if that helps my cooling at idle.
Joined: Tue Oct 11 2005, 01:33AM
Location: Calgary, Alberta
Posts: 5893
Outstanding find!
It's interesting that the stock Mopar designs, tests 1 and 9, seem to have the best flow rates for general city driving. At higher rpm the flow rates on all seem to start to drop off, but the increased road speed and air flow through the rad should compensate.
The fancy looking cast aluminum pump with the high tech looking swirl blades, test 2, is a surprise. Can't judge a book by its cover.
Joined: Thu Mar 01 2007, 09:30PM
Location: Houston
Posts: 1735
Interesting information....but as with exhaust systems I don't think anyone knows half as much as they think they do.
For example, we all clamor to get our hands on the highest flowing water pump, right? Well, who said the most flow is the best? And maybe, or maybe not, the more flow you have the greater your HP loss.
Joined: Sat Aug 19 2006, 05:03PM
Location: Ontario, Canada
Posts: 2919
Bill and I debated cooling system dynamics in a previous thread. To paraphrase what Bill said, if the cooling system is running with the thermostat wide open it becomes self-regulating, so difficult to say what changes would be required to improve performance. You may be forced to try changes by trial and error.
This information moves the effect of the water pump from the realm of the unknown to the known, which is definitely a good thing. It quantitatively shows that the water pump may be part of the problem, and suggests what to replace it with if you think you want more or less flow to reduce the equilibrium temperature. If your choice was wrong and the cooling system performs worse, you'll have a good idea why.
Fortunately, big block water pumps are relatively easy to change too. <span class='smallblacktext'>[ Edited Fri Jan 22 2010, 06:57PM ]</span>
Joined: Tue Oct 11 2005, 01:33AM
Location: Calgary, Alberta
Posts: 5893
gregcon wrote ... Interesting information....but as with exhaust systems I don't think anyone knows half as much as they think they do.
For example, we all clamor to get our hands on the highest flowing water pump, right? Well, who said the most flow is the best? And maybe, or maybe not, the more flow you have the greater your HP loss.
Very true, biggest, tallest, shortest, longest, fastest and any other ***est you can think of, make for good bragging rights, but as my Dad used to say "that plus two-bits will buy you a cup of coffee". I guess today its more like 2$.
Myself, I want a water pump that produces enough flow at low rpm to cool my engine in city traffic but not so much flow at high rpm that it blows out my rad. From what I see, that's a stock Mopar unit! !thumb
Joined: Thu Mar 01 2007, 09:30PM
Location: Houston
Posts: 1735
I agree, the stock pump is probably just right.
More flow....could run the water through the radiator too fast and not allow it enough time to lose its heat. Similarly, it could pass water through the block too quickly, not allowing it enough time to absorb heat.
In heavy industry there are a lot of standard for heat exchangers that regulate flow conditions for the above reasons. Also, too much flow can erode the cooling system prematurely.
