The 2nd gen RX8 is weird.
    The last one looks more like a
  RX7 2nd
    gen

    Paul


  Paul,
  If we think of impeller leading edge as
  a wing gently entering the water
  stream... and then the trailing edge
  mimicking a extended wing flap...
  directing as much water as possible
  into the pump housing scroll.
  The computer model helps us not stall
  the "wing" or congest the flow at
  any point on it's surface (or between
  adjacent surfaces).  We would like
  to have each section do equal work.
  Then Mazda's new design makes more
  sense.
  Barry Bordes

  The water must make a sharp right
  angle. It comes in on the same axis as
  the pump shaft.
    Then it must turn 90 degrees and
  flow outward towards the housing scroll.

  The device that does this well, using
  air, is a turbo charger compressor
  wheel.

  I suspect a good water pump would work
  the same way. I could be wrong of
  course
  but I would like to see some comparison
  data and a CFD before I would be
  convinced.

  Turbo charger compressors are hard to
  make. They are probably machined
  on a 4 or 5 axis
  NC mill. Too costly for a car.

  High pressure die casting  them
  would be very hard to do I suspect. The
  mold must be
  made in perhaps multiple parts to get
  the finished product out of the
  mold. Very expensive.

  In the case of a water pump It may be
  necessary to make them in iron or
  steel for long life.
  That prevents high pressure die
  casting.

  In the case of the 2nd gen RX8 that
  could be done in a simple iron or
  steel sand or ceramic casting.
  There are no 3D double curved surfaces.
  It is probably better than the
  stamped steel
  first gen RX8 or 3rd gen RX7
  impellers.

  It remains to be seen if the aluminum
  after market NC Mill  impeller
  will hold up for long periods.

  We are using the KSE water pump on the
  time to climb. How that is made I
  know not.

  Paul Lamar

I would like to see some quantitative data back to back with the first gen RX8 impeller.
Should be easy to do with a 2 HP AC electric motor and a fixed orifice say 3/8th
of an inch to simulate the restrictions in the engine block. Measure the pressure
just before the restriction.

This will give us data at one RPM unless you have a stepped puley on the
2 HP AC motor.

Paul Lamar



Hi Paul,
    These water pump and turbo impellers can be made these days by 3D printing
using laser powder technology. Even turbine wheels too, fault free and very accurate.
    Chris Hoskins.

Yes but 3D printing is too slow for production. It would cost a small fortune in terms of corporate time.
When these are sand or ceramic cast ten or more are cast at the same time.
It only take a few minutes.

The same goes for rotors. Mazda recently updated their casting techniques
and now rotors are more accurate when they come out of the bold.

Paul Lamar

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