The restrictor is on the water outlet, and the top hose is the same size
as a street Mazda. The radiator is a Griffin double pass aluminum. 3" by
19" by 31" Two rows of 1 1/4" tubes. Both inlet and outlet on the
passenger side.

Here is a picture of a cooling system that has worked for me since 1980.
I added the Rol-air-trol. A home made version of a air/water separator.
I used to manufacture heat transfer packages that used a giant version.
I thought Bell and Gosset made those but now I don't see one in their
catalogue. When pumping hot water around a building, you must remove all
of the air from the loop. When air goes through a pump, it expands
violently (cavitates) at the pump inlet and may damage the pump, and it
makes an awful noise at the pump, and going through fin tube cabinets in
each room. Nothing is as funny to school kids as a fin tube cabinet that
sounds like it is having a diarrhea attack. So air in the loop is just
not allowed. The air removing device helped me get the air out quickly
without hurting the engine, as my system may be drained often. It is
difficult to remove air from the rotary when it is level. More so if it
is not level. The rest of the system is what you would have found on
every RX-2 and RX-3. The pressure bottle is kept 1/3 full of coolant.
When air is delivered to the pressure bottle, it pops to the top and
only airless coolant can be forced back into the system when a
temperature/volume change occurs. In two or three heat cycles the system
will be solid coolant. The bottle must be refilled after each heat
cycle, but not over 1/3 full. I have a Shrader valve on my bottle, so I
can be at relief pressure before the engine starts. Probably not
required for airplanes. You could also add the pressure gage on or close
to the bottle for easy reading, and or, a gage on the dash to view
coolant pressure. The racing organizations require that catch tank, but
there is never anything in it.

I used a stock RX-2 pressure bottle, but a better choice would be an
aluminum aftermarket bottle to get a good selection of cap pressures.
The pressure cap is on the bottle. Not on the swirl pot. That cap is
solid and used to fill the system.

Lynn E. Hanover