Is it possible to design any test that would be relevant, other than a
flowmeter with the actual engine, swirlpot and radiators in the loop?
Bob's numbers sound like they would work for me (30GPM is the mininum
right?), but only if there would be significant flow recovery from the loop.


Why wouldn't you want to do the test with the actual engine and cooling
system in place? When I did my test I had my cooling system in what I hoped
at the time was it's final configuration. I did make a few changes
afterward, most notably was the change of my hoses from 1" to 1.25" along
with a more direct flow path enabled by the use of moulded rad hose (hard to
make bends without a kink in straight hose) in an effort to ensure I had
little to no energy loses in the plumbing. I also fabricated my own header
tank afterwards to place it in a better location (high on the FW), but these
change would only improve the flow.
The biggest error that I made was that I didn't use a 14 volt power supply
to power the pump to ensure that I had full bus voltage. At the time I was
more interested in how it would perform running on battery only and for how
long, since at that time it was widely believed that battery death would be
instantaneous without the alt.
If it wasn't that the magtube and transmitter that I used were far to
heavy, bulky and expensive to use in flight and the fact that I just don't
have the time, I would redo these tests.
I do however have a small paddlewheel sensor installed in the main coolant
line, however I just use this to output a 0-45hz signal and convert this to
a 1-5 volt signal which I input to the EM2 and display as 0-100, with an
alarm set for 50.
Anyways, my point is that I feel that all this testing using barrels of
water etc, may be misleading. While I can understand the desire to do
preliminary testing before the engine is actually ready for that, I think it
may be wiser to wait until the engine and cooling system is mounted and in a
reasonably close to final state, otherwise the results may be meaningless.
Just one man's opinion.

Todd Bartrim   (happily flying a turbo with far less than 30gpm)

RV9Endurance
13B Turbo Rotary
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm

             "The world will always have a place for those that bring hard
work and determination to the things they do."