Lynn, there is an unused water connection on my rear iron. At
present I have a short hose on it and it’s plugged.
What about extending the hose a bit and replacing the plug with
a snifter valve, or keeping the plug and using this hose as an auxiliary water
filing point? It could easily be elevated to the highest point in the system
and used as an air burping point on the ground.
Jeff
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Lynn Hanover
Sent: Tuesday, December 09, 2008 7:34 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Three more flights, water ok, oil too cool
There used to be a water temp sensor in a hole in the flat spot in
the top of the center iron. Done away with years back, it was a perfect place
to let the air out of the block. The air is now removed slowly because the
front of the engine (in the car) is tipped up a bit, and the air collects near
the water outlet, and is eventually pumped out of the block to be removed to
the top of the radiator where it sits still until the cap cycles and lets some
of it out. When the front of the engine is level with the back, or, tipped
down, this is no longer possible. Air pools at the rear iron and there is not
enough flow rate to move it anywhere.
At 30 degrees, you are close to not needing a water radiator to
cool the engine. The engines are cold blooded, and do not start readily when
carburetted. The intake looks like Santas beard until some heat is built up. We
tried to race once when the temps were that low. I got mine to start with two
cans of WD-40 spraying into the carb at once. Then when the WD-40 was shut off,
the engine would die. We got it hot by dragging it around the paddock with the
tow vehicle. The ignition was on and the fuel pumps, but it did not make enough
power to run by itself. So we did a few laps with the enging half running, and
it got some heat into it, and could fast idle (2,200 RPM) on its own. It had a
160 degree thermostat with a 3/16 hole through the rim to let air bubbles
through. After a few light laps with 2/3 of the radiator taped over we got 120
degrees of water temp. The engine was cooling with a 3/16" water supply.
I took out that thermostat and put in a 180 degree thermostat
with no holes through the rim, and that got us enough heat to race on. 150
degrees a speed.
The complex and expensive stock Mazda thermostat was designed
to provide a closed loop of coolant in the block to heat the engine rapidly,
and uniformly. The two reasons are: Poor combustion in the large and cold
combustion chambers, thus high HC output, and the block is heated on only on
the plugs side. Inlet air and fuel on the exhaust side overcool that side.
So it is the job of the coolant to keep the exhaust side of the engine close to
the temperature of the plug side so the engine remains about the same length on
both sides. So, there are more case bolts on the hot side than on the
cold side. You may discover that when overheated massively, the rotor housings
on the hot side will be shorter after the engine cools, and begin leaking
water. There is also a need to have more clamping around the combustion chamber
to prevent scrubbing the housings on the irons. Very high output engines use an
additional dowl around each case bolt to prevent such movement.
A fixed rate of heating to an overheat suggests too small a
radiator. A rather sudden overheat suggests trapped air in the system. If
radiator size is marginal, a reduction in power will reduce coolant temps. If
the system has air in it, the temperature will remain high or go still higher.
For oil cooling, the power setting has a closer connection to the
temperature. So on a scalding hot day shifting at 9,400 RPM rather than 9,600
RPM will bring the oil temps right down. I look for 180 water and 160 oil,
but 200 water and 200 oil won't hurt anything.
Yes, I
recall that you and Jim did use a thermostat plugs up with no problem. I
found burping the block (actually my cores) necessary even without a
thermostat. It could be that I did it the same number of times I did
without the thermostat and that was insufficient.
I normally
would run the engine 5000 rpm for 30-40 seconds to burp the air. Would
need to do this about 3 times before I got all the air out of my cores.
Because of my ignorance of all factors early on when designing the
plumbing for the cores, I had both inlet and outlet on the bottom – not
conducive to getting air out of the cores.
So should
have one tube going in the bottom and the other out the top or both out the top
or at least a spigot on top to release the air as the tanks filled.
You know – the old "should have, could have, would have -
but didn't". Now it's just simpler to burp the engine three
times on the infrequent occasions I drain the coolant.