I am not sure how to do a drawing of my system, but following along with your drawing…

From the water pump, I don’t have a thermostat or restrictor or swirlpot.  The line goes from the pump to the inlet of the double pass radiator, across the top of the radiator, where there is a radiator cap.  At this point the ¼ inch line from the top of the rear iron comes into the radiator just below the cap.  I also read my system pressure at this point.  The cap is a fill cap, not a pressure cap, so air that comes up under it can travel down a 3/16 tube to a modified fire extinguisher with a pressure cap on it. (just like your RX-2 make up bottle with the lever cap)  This fire extinguisher is kept about 1/3-1/2 full of coolant.  I currently do not have an overflow bottle on the outlet of this pressure cap.  So far I have not had any liquid come out of that overflow.  I am thinking that it may be a good idea to add one, but it would need to be small for weight.

Now back in the narrative to the inlet under the radiator fill cap.  When coolant comes into the radiator at this point, it travels down the side of the radiator and across the bottom half of the radiator and into the suction of the pump.  One downside for my setup is that the coolant coming from the rear iron will only get one pass of the two pass radiator, but it hasn’t been thru but one pass of the two pass engine.

I plan to use the coolant for a heater, so currently there is a hose that connects from the heater outlet on the side of the rear iron and goes around to the suction side of the pump.  I am still looking for a suitable heater heat exchanger so I don’t have this hooked up to a heater yet.  Anyone with a good idea here would be appreciated.  I don’t have much room for the heat exchanger so it must be pretty small.  I have a cable operated valve to shut the coolant flow on and off after I have installed the heat exchanger.

I think my system would work very similar to yours.  It may take more than a couple of heat cycles due to no swirl pot, but when air comes out, it is trapped and only coolant can return.  I always check the fire extinguisher after an engine run and after a while??? Don’t have to add more coolant.

Where does one come across an RX-2/3 pressure bottle??  

I welcome comments on this set up.

Bill B

Lynn,

You sent that drawing some time ago during a previous discussion on cooling.  My system is set up very similar, but I wonder what the effects of the differences might be. 

I don’t have a swirl pot, but the cap on the radiator is like in your drawing where it doesn’t seal for pressure.  Another difference is that my radiator is a double pass, so the radiator cap is after the first pass of the radiator.  You don’t show where you come in with the air bleed from the top of the front iron.  Mine comes in just under the radiator cap.  This allows the air to move into the make up bottle quickly.  But the down side is that whatever coolant comes thru that ¼ inch line bypasses the first pass of the radiator and only goes thru the last pass.  However, I think that this coolant has only made one pass thru the engine as well.

( I have no clue how the coolant flows thru the block, but I think it goes down one side and back up the other side to the water pump???)  I would like someone to set me straight on this coolant flow thru the engine.  There are two outlets, this one and the heater supply that come off the front iron.  They must somehow only get contact with half the engine since the water pump is on the other end of the engine. ???

Bill B

 The air from the engine leaves the top of the swirl pot (in my case) and enters the stock RX-2 make up bottle at the bottom center. I have no other lines to the make up bottle other than the line from the neck above the pressure seal that runs to the catch tank required by rules.

The dynamic fluid flow does not require exact top collection of air as would a static system. Air is swept along with the coolant and tends to collect only in still or very low flow areas like the top of the radiator tanks. Thus the swirl pot, that removes air from a high energy flow.

My radiator is a double pass to get more energetic flow and have both inlet and outlet on the same end.

Coolant flows back along the sparkplug side to the rear iron, across the rear iron and forward from rear to front along the intake and exhaust side, then out through the water pump housing.

Lynn E. Hanover