Just as an aside cavitation can be heard so with some electronic gear and a
small bedded mike and some filters for obvious noise sources there will

be a

distinct change in noise as cavitation starts.

In an industrial environment, the pumps and valves I've heard cavitating
sound like they are pumping gravel.  It's loud enough to be heard over
other machinery where hearing protection is required.  On a small pump like
the rotary water pump the engine could drown out the noise but the test rig
that Vance is building should allow you to hear it just standing next to it.

Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode

I want to make my position clear on this. I am not saying these pumps
did not cavitate. Perhaps that is what  happens when they are run
at 5000 RPM with low water. What I doubt is; these pumps cavitate
with a full cooling system merely by running them at the range
of RPM's typical of street car and airplane use.

Paul Lamar
 
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