At 09:52 AM 1/19/00 -0500, you wrote:
>The flow kooler water pump has a steel disc, that you pop rivet to the
>stamped steel impeller, making it a closed impeller. This type of
>impeller is much more efficient than an open impeller, and is used on
>higher efficiency water pumps everywhere.
>
>You can buy the kit for you pump, if it has a stamped steel impeller,
>for around $6 at Summit, or buy their pump for around $70.
>
>Larry
Like every mechanical device, water pumps have distinct operating
characteristics and limitations depending on their designs. Ford
discovered that their normal production water pumps tended to cavitate and
cause problems when they were run at high engine speeds on a continuous
basis such as track racing. At that point, most production pumps were of
the radial vane type which worked well at "normal" engine speeds. They
were surely not the first to utilize reverse pitch impeller blade designs
but that's what they found as their solution to high speed cavitation.
The phenomena involves the velocity and pressures of the coolant as it
leaves the tip of the vane. Straight radial vane pumps, run at excessively
high speeds, reduce local pressures in the area just off the tips that
allow the water to burst into steam bubbles which is cavitation. In
addition to reducing overall cooling efficiency, this cavitation also has a
very nasty erosion effect on the aluminum in the vicinity. I have never
seen a Flow Kooler pump so I don't know what their design looks like, but
if it has radial blades, as most stamped impellers do, it will have the
same operational limitations regardless of it's "efficiency". If you
intend to use your car in event that will require continuous high engine
speeds it would be worth the effort to find a reverse pitch pump.
Tom
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