Hi,
    Finally, got the rotor in the mail. Thanks to Paul. (Is it RX8
   rotor? I remember that You mentioned that pocket and faces are
   machined. On this one pockets a left as cast.)
   I agree totally with what Paul and Rob are suggesting.
   Next steps:
   1) Disassemble it.
   2) Cut in two halves.
   3) Scan it.
   4) Create a valid 3D model of standard Mazda rotor.
   Here I will need help from Rob.
   Rob, as I understand You've got all the math to model the rotor
   faces. If I remember correctly You're working with Pro/E. Is it
   possible that You model outer geometry (faces) and send me the file
   (native Pro/E or any common - Parasolid, Step or IGES). Modeling the
   faces out of scan data is not the best idea IMHO.

   5) As Rob mentioned "Cast Ti has anywhere
   from a 1/2 to a 1/3 less thermal conductivity versus cast irons. 40
   percent less density, half the expansion rate, double to triple the
   tensile strength but anywhere from equal to half the modulus of
   elasticity. If i were just looking at it, without changing any
   dimension(based on modulus vs. tensile) it would be about 40 percent of
   the weight of the rotor."

   If I remember it right Mazda rotor is made out of ductile iron. Its
   properties:
   Elastic Modulus 120000  N/mm^2
   Poissons Ratio  0.31
   Shear Modulus   77000   N/mm^2
   Thermal Expansion Coefficient   1.1e-005
   Density 0.0071  g/mm^3
   Thermal Conductivity    75      W/m K
   Specific Heat   450     J/kg K
   Tensile Strength        861.695 N/mm^2
   Yield Strength  551.485 N/mm^2


   Now for the Ti cast rotor I'm planning to use VT20L which was
   designed for extended work at 500C.
     Fe     C      Si       Mo    V    N       Al    Zr       O         H
   <0.3   <0.1  <0.15    2     2.5 <0.05    6     2    <0.15  <0.012

   Elastic modulus 123000  N/mm^2
   Poisson's ratio 0.33
   Shear modulus   46000   N/mm^2
   Thermal expansion coefficient   9e-006
   Mass density    0.00465 g/mm^3
   Thermal conductivity    7.8     W/m K
   Specific heat   500     J/kg K
   Tensile strength        1160    N/mm^2
   Compressive strength    1170    N/mm^2
   Yield strength  1070    N/mm^2
   Hardening factor (0.0-1.0; 0.0=isotropic; 1.0=kinematic)
    8.5e-007        N/mm^2

   Advantages that we may have:
   Strength =   134.6%
   E modulus = ~ 100%
   Density =  65.5%
   Thermal conductivity =  10.4%
   Thermal expansion =  82%

   More than that at high temperatures  mech. prop. advantages will be
   higher.

   Anyway as Bob mentioned we can  safely assume 30% weight reduction
   of rotor assembly. I agree with Rob that revving the engine 20000RPM
   may cause all sorts of problems. But revving the  3 rotor engine to
   12 - 13,000 RPM sounds realistic to me.

   Now, what's the current thinking about feasible price for a 7 -
   6.5lb Titanium rotor? We're not talking about mass production but
   high power applications.

   Thank You
   Ted


Paul,

Thanks for your work on this newsletter.  Fascinating stuff. Hopefully
I'll get to benefit from your work someday. Just a comment: investment
cast and even some forged Titanium golf driver heads, though in much
higher production than this group might generate, have dropped their
prices steadily. Numbers would simply be speculative, but someone should
be able to do this project at a reasonable rate.

Michael Francisco

Ted is in Russia the home of titanium so he can probably do it cheaper
than anyone over here.

Ted, that is a pre 89 Mazda 13B rotor. Very little differences except
the RX8 has more side seals.

Paul Lamar