> > Hello all,
 > > > This is in regard to the spark plug cool that is being discussed. I
 >came
 > > across this on the RX7club.com site. I pleasantly surprised to see the
 > > amount of technical experimentation that some on this board try. I
send
 > > the good nuggets I come across.
 > > > http://www.rx7club.com/showthread.php?t=751977
 > > > > Rob Woods
 >
 >Interesting thread. So far it has been unnecessary to modify the rotor
 >housings
 >for rotaries used as aircraft engines. These guys may be at the 150 to
 >200 HP per rotor level. Here is a trick all should do if they get a
chance.
 >It relives any steam pockets that may be generated around the spark plug
 >area.
 >
 >Also the 3rd gen water pump and RX8 water pump are less than ideal.
 >The Rx8 in particular as it is much smaller than the 2nd gen water pumps.
 >Somebody is already making a better impeller for the RX8 engine but I
 >have not
 >tracked it down yet.
 >
 >The bottom line is you need to know what is happening and the only way
 >to know that is measure the "cylinder head" temperature with thermal
 >couples
 >embedded in the roto housings.
 >
 >Paul Lamar
 >
 >Paul,
 >Do you know if anyone has tried a better water pump? By that I
 >mean a separate engine driven after market pump. I have found at least 2
 >examples Mazarre (sic) makes a engine driven pump intended to replace a
 >standard pump on a V-8 chevy. They have a performance chart for the pump
 >on their site explaining that the pump requires about 4.8 HP to
 >move 60gpm "with normal engine back pressure." They do sell the
 >electric water pumps, but only claim they are good for drag racing, NOT
 >for road use. As we have told people forever it seems. 5 HP sounds about
 >right on their engine driven pump if they are moving that much water
 >without cavitation. The Wisconsin powersport guys said they had tested
 >the standard second gen pump and it was topped out at 53 gpm at the
 >verge of cavitation. I wonder if we could move more water and solve that
 >problem? I also like the original PowerSport efforts into center feed
 >cooling. That seems like a better idea over all if you are going to run
 >at those power levels. Perhaps Steve might tell us if that was ever
 >followed up on?
 >Bill Jepson
 >
 >Cooling with a 2nd gen pump is just not a problem for aircraft use.
 >Mark Steitle with the installed thermo couples is not reporting
 >any problems so far. Mazda data at 7000 RPM has the "cylinder head"
temperature
 >100 F lower than a water cooled Continental aircraft engine like the one
 >that went around the world in the Voyager.
 >
 >There is an after market pump that Jim Mederer used on one of his
 >1200 HP turbo 3 rotors. It is used on 800 HP sprint cars and it is
made by KSE
 >as I recall.
 >
 >Changing the cooling system from series to parallel As P.S. attempted
and NSU
 >used would be a worth while thing to do but it is near impossible
without a
 >complete redesign of the engine. The fact of the matter is nobody,
unless they
 >are building a Reno racer, are going to demand much over 300 HP as
they don't
 >want to burn the fuel.
 >
 >Paul Lamar
 >

Paul,

I found the KSE site and the pumps aren't that expensive but yes they
are still overkill, unless a bypass valve can be milled into them and as
such will allow us to adjust the flow we want.
Could you explain the advantages of the way Jim routed the second outlet
into the front housing?
I believe both inlets go into a common cavity in the front housing.
Could the pump inlet be connected to the outlet of the radiators?

Bill I had no luck on finding any company website close to the name you
mentioned. Could you send the URL to us?

Doug in Japan

I can't read Jim Medere's mind but perhaps this drawing will give us
some clues.

Also this is an excerpt from Max Bentele's SAE 1991 book Engine
Revolutions.

Max was working for Curtiss Wright in 1958 during the early days of the
rotary.

"Chapter 8 - The Rotary Engine Era"

"Cooling of the trochoid housing presented the greatest challenge. In a
reciprocating engine, cylinder head and piston dome are exposed to all
phases of the working cycle. In contrast, the individual portions of the
engine outer housing are exposed only to their respective phase.
Temperature and flow velocity of the working medium, and thus the heat
flux to the housing wall, vary along the trochoid circumference. Two
extremes exist: In the combustion zone, the very high heat flux will
induce nucleate boiling of the cooling water; in the intake area, the
inflowing fuel/air mixture is, due to fuel evaporation, colder than the
ambient atmosphere and much colder than the cooling water. The design
task was therefore twofold: (1) to prevent overheating and resulting
thermal cracking of the housing in the combustion zone and (2) to
minimize thermal distortion of the housing and to assure effective gas
seal operation."

"We soon realized that NSU's circumferential cooling flow was incapable
of fulfilling all requirements of high-performance engines. We selected
axial flow, back and forth between the side housings, with the flow
velocities in the various rotor housing sections adjusted to their
respective heat input. In the combustion zone, the high-velocity cooling
flow removes the steam bubbles generated by nucleate boiling, and thus
permits extremely high heat fluxes to the housing without detrimental
effects. This cooling scheme was also beneficial to the structural
integrity of the rotor housing. Engine test runs confirmed its
effectiveness in all respects. It was patented and became the standard
for all high-performance Wankel engines."

What Mazda did not do is adjust the flow velocity between front and rear
rotor housings let alone the 3 rotor. Rotor housings are interchangeable.

BTW nucleate boiling is good boiling.

Paul Lamar

Paul & Doug,
The MEZIERE site is www.meziere.com <http://www.meziere.com>. They have
changed their site since my last visit and no longer have the pump HP
charts available. They probably got too many questions about the
effectiveness of the electric water pumps. The KSE pump was the other
pump I first checked out. KSE is supposed to have a mount to run the
pump directly off the back of a dry sump pump. They designed it for the
sprint cars that run the dry sump pump off the cam cover.
Bill Jepson

--

Bill


Thanks.  Yea I did find that site but the amperage draw verses the
performance looked dubious to say the least.  Here is a good company
that offers many pumps albeit ones we would have to adapt.  They seem to
have experience supplying the racing community.

http://www.stewartcomponents.com/index.html

Perhaps we can modify one.

The tech notes they offer are especially pertinent as pump performance is
directly related to the head they have to pump against.  55 gallons a
minute at zero head is unrealistic.

http://www.stewartcomponents.com/tech_tips/Tech_Tips_6.htm

As quoted:

"Proper bench testing of accessories is the only proper method of
development. The accessories affect so many functions of the engine that
testing them on a running engine on the dyno is a total waste of effort.
The coolant pump is a great example of an accessory that must be tested
and developed off the engine. To bench test the coolant pump you must
know pressure drops at a given flow for all the components of the
cooling system.

Following is a typical Winston Cup engine at 100 GPM:

Lower radiator hose = 1.5 PSI
Block and cylinder head - each (at 50 GPM) = 8.5
Outlet manifolding = 1.25
Top radiator hose = 2.25
Radiator = 1.5
Total = 15.00 PSI

In addition to having the proper flow restriction as expressed in GPM @
PSI, the cooling system pressure and temperature must be known. All
these conditions are duplicated for the bench test.

Energy losses due to driving the coolant pump can only be calculated when
all conditions are duplicated and torque and RPM measured. Amp draw of
the drive motor is not an accurate measure of the energy required to
drive the pump. Torque must be measured with a load cell and horsepower
calculated from there.

Doug in Japan


Good work Doug.
Excellent web site. I have always been impressed with Stewart Warner.
They always present excellent data and good information.


Paul Lamar