X-Mozilla-Keys:                                                                                 
charles.harbert wrote:

I had a similar question to Ed's. It seems strange that with all the racing of
the Mazda rotaries that the water pump capacity is now just being discovered to
be inadequate. I read the Stewart internet tech info which was a very good
(actually excellent) discussion of water pumps and cooling systems.  It says
that you should have high volume for best cooling in higher hp engines, but you
better have the rest of the cooling system designed for it. This would include
the thermostat, hoses/lines, radiators, and (very important) the engine. If you
significantly increase the flow rate, the rest of the system must pass the
additional volume without significant restriction. Otherwise, the pressure
increases and you waste horsepower thru pumping losses.

 http://www.stewartcomponents.com/techtip5.htm

I suspect that Mazda designed their system to flow at certain rates that
produced a reasonable amount of friction loss. I remember a previous discussion
where it was said that above 7,000 rpm the stock Mazda pump cavitated and you
would need to slow it down to prevent this. Another point is that many of the
a/c Mazda's have the pressure cap on the pump discharge side which is exposed to
pump pressures. The Stewart tech articles caution you to move it to the suction
side, or you can open it with high pump pressures.

One check you can do is add up all the areas of the flow passages in the
rotor
housing and compare it to the area of the hose from and to the
radiators.
On the cool side of the rotor housing Mazda has actually placed some
restricter
orrifices. Another little reality check is add up the area of all the
tubes in the
radiator. I think you will find that the areas in the rotor housings are
far
larger than the hoses. I also think the same think can be said about
your
average radiator. As a quick check I got about six square inches for the
rotor
housing and about 1.3 square inches for a 1.25 ID hose and 2.4 square
inches
for a 1.5 ID hose. PL

What I'm suggesting is that we make sure that what we do with the water pump
really does improve the system and that testing is done on the new pump to be
sure it matches the rest of the system. Paul Yaw has the capability to do this
type of testing and can outline the parameters needed for the new pump.

With all that said, I'm interested in your new pump. By the way, I have the
early style pump with the pres cap/fill right above the pump.

p.s. The Stewart Stage 4 pump had some very impressive flow vs. hp numbers. They
talk about an 8 vane impeller.

 
The Aircraft Rotary Engine Newsletter.              Powered by Linux.

http://home.earthlink.net/~rotaryeng/            http://www.linux.org