Hi Ed,

 My thoughts on making the rotor housing steel liner for a 13A/16X
 size radius
 would be to try to get a 13A engine. Doug, would you have any leads
 on one in
 Japan? With that we would have the shape of the inside. Casting a
 steel shape
 that is the inside dimension would help form the proper shape. We
 would need a
 die for the outside so it forms correctly. Figuring the inside
 circumference
 would enable machining a 4130 pipe ID to that dimension. Then
 machine the
 grooves in the OD with a tapered burr so the cast Al forms into it
 and can not
 come "unglued" or separated. Then forming it with the dies to the
 shape. The
 Al could then be cast around it and the width machined. The area for
 the Pport
 could be left without cooling to eliminate sealing there, and the
 port almost
 ready to go.

 Anybody alse have an idea on this. Paul, what is the thickness of
 the Mazda
 steel liner?

 Dale Davies

 It is very thin. On the order of .065. Here is how Mazda does it.
 You would be reinventing the wheel :)

 Paul Lamar


Dale Davies, I don't think you need a housing to measure. There is in
the Kenji Yamagughi (sp) papers found on the rotaryeng.net
<http://rotaryeng.net site the formula for generating the shape of the
trycoid housing. It is generated by  the path of the 3 rotor tips as
they revolve while the eccentric shaft rotates. You can generate
cartesian or polar coordinates to as many decimal places as you desire.
I think my desktop does to 27 decimal places but I have it set to 5
since that is ten times as accurate as CNC can machine and more just
increases the file size. A CMM (coordinate measuring machine) is not
this accurate.

If you change either the eccentricity or radius you will be
makeing a new trichoid shape that hasnt been produced and therefore
there aren't any parts to measure. The Lada and Chinese rotaries both
use the Mazda dimensions. Curtis Wright has a vast number of
displacements for use as both engines and pumps.Some are six feet tall
inside the rotor housing. They all seem to have the  same ratio of
eccentricity to radius. If you increase eccentricity relative to the
radius you improve torque, however I suspect it will not have as high an
RPM as the current optimized dimensions. Changing the ratio also changes
compression ratio which will require building a matching rotor with the
correct combustion chamber depression. The volume of the depression for
a given compression can be derrived from formulas posted on this site
last year. If you leave the ratio the same and go larger then the
currently designed end housing databases can be 3D scaled up in the X
and Y dimensions with the same Z  saving some design work. Several of us
have end housing databases including Jeff and myself.

  The problem with building rotor housings is the final finishing
steps. They need machined and lapped to .0001 accuracy. This is
currently done on specialty equipment and not likely possible
with normally available  CNC machine tools.

  Although scratch building a rotary engine is a huge task, by the
time you are able to fit lubrication and cooling oil flows  and coolant
glycol through the mechanical and structural elements of the engine you
will be better able to modify the available parts to suit your needs.


george grimes


Hi

We tried this at Norton circa 1976, we squashed a tube down to an oval
shape, machined the Alum housing to match the Oval. then Kopp ground the
Housing shape, but even then we could not transfer the heat away from the
chamber, and the Air cooled engine would not pass a hot stop test, even with
the best oils of the day, if we carried out an emergency stop from a
sustained WOT  and switched off and left the motor to cool down, invariably
the seals would stick and blow pass would start, and this eventually caused
the Rotor side face to smear.

I agree with a lot of the comments, however would also point out that the
Seal nose Radius needs to be and was matched within the geometry, on the
Norton we changed from R=70, e=11.6, a=0.5 to R=69, e=11.6, a=2.5 and this
helped the chatter and apex seal spring wear rate. with the original
geometry lubrication the seal would wear in quite readily to match the
geometry, but it could never match exactly, this caused a radial apex seal
movement of around 0.007 " can't remember exactly and seal would work this
cycle four times per seal rotation, when we went to Water cooled engines the
seal spring failure overtook the after bake problem.

With regards to Mazda, if it is not broken then do not try to fix it, I
visited the plant for a week in 1988 and admired the Engineering immensely,
I was allowed full access to the development facilities and we had at least
3 engineering meetings within the week in which we talked openly about our
problems, both direction, I would not elaborate on Mazda issues of the day
even to this day as we made a Gentleman's agreement not to digress.

Bob Rowley
Ex Chief Test rider for Norton Motors Ltd
over 1 million miles testing Wankel engines from 1968 (BSA) to 1993

Very impressive Bob. I toured the engine plant but not
the engineering labs.

Paul Lamar