I started racing rotary powered cars in 1980. An RX-2 with a junk yard
engine. Had to pour motor oil and hot coffee into it in order to start it. No
compression. People gathered around just to watch me do it. Ran well, never a
reliability problem. No overheating problems. Oil cooler was an air conditioning
core from a large GM car. Cheap and available.
I copied the cooling system from the stock RX-2. It had a coolant recovery
tank made of plastic. The pressure cap was on this tank. The radiator cap was
just to seal the system. Those engines had the giant monkey motion thermostat
that closed a hole in the water pump body after a quick warm up.( Pollution
control). Stock radiator. Bigger oil cooler. No problems.
Then I started building bridgeported engines. Big problems. I installed a
big aluminum radiator. A double pass top to bottom. This put both inlet and
outlet on the same end. Very handy. No problems for a while. Then an occasional
overheat after an engine change. I could not get all of the air out of the
engine after a rebuild. I lifted an idea from the Cosworth
installation manual and installed a swirl pot. The top of the swirl pot plumbed
to the bottom of the stock RX-2 recovery tank. So as the engine warms up any air
removed by the swirl pot enters the bottom of the recovery bottle. The bottle is
kept half full of coolant, so the air pops to the top of the bottle. On cooldown
or off throttle situations only coolant can return to the engine. After several
sessions of refilling the bottle to one half full, the engine has removed all of
the air and full RPM shifting is available. For us that was shifting at 9,600
RPM. Coolant temps 180. Oil 160. At low RPM the air will not come out of its
hiding places. My idle was 2,200 RPM. Timing is checked at 4,000 RPM. Clear out
the bubbles at least at 4,000 RPM.
On cool days (below 65 dgrees) we would install a thermostat that had
two 5/16 holes drilled through the flange.
And tape over half of the radiator.
Some items are not obvious.
The best coolant pump location is at the very bottom of the coolant
loop. The rotary pump is at the top of the coolant loop. The pump will gleefully
stop pumping if a dose of air enters the suction side. Very bad MOJO. The
center irons on 12-A engines at first had a temp sender hole. Great place to let
air out of the coolant before start up. Then the hole was filled in but the
machined flat was still there as well as two tapped holes. I drilled and tapped
for 1/4 pipe and installed a radiator bleed fitting. Got out lots of air before
even running the engine.
The recovery bottle need not be mounted high in the circuit. That bottle
in the racer is mounted on the passenger floor. Also the top of the swirl
pot need not be mounted high in the coolant circuit. Does not matter.
I found a Stant pressure cap for the RX-2 bottle rated at 28 pounds. I
installed a Shrader valve in the swirl pot and pressurized the whole system
to 28 pounds before start up. This also tests the pressure cap.
My coolant is 10% prestone antifreeze. 1 bottle of RedLIine Water Wetter,
or 1/2 teaspoon of Dawn dishwashing soap. The rest is distilled water. And
28 pounds of pressure.
The racer is gone now but the last iteration of the coolant system is as
above. The oil cooling had to be improved as HP went up. (Store bought engines).
Daryl Drummond 250 HP 12-As. So the last oil system was a full dry sump with one
44 row setrab in the pressure loop. And two 44 row setrabs in the scavenge
loop. We ran 100 pounds of oil pressure with 40 weight RedLine racing synthetic.
No oil related failures
since 1980. The modern "Square" Peterson pumps tend to split open the
pressure section. I changed to the older round body Peterson, no problems.
Lynn E. Hanover
I will draw the coolant loop if you like. It was published many
times but died several computers ago.