Paul,

  Just playing around with some ideas on TC..This concept I am sending for
  critique, understanding that this was put together in just a few
  minutes...

  The Idea here is to bolt the 2 exhaust housings up close and personal,
  with some kind of adapter so they align with a sandwiched gear box that
  resides where the compressor used to be, reducing rpm to the upper
  shafts..

  One shaft translates outbound to the single compressor in a housing
  where it bumps the rpm back up to compressor speeds needed..the other
  translate in the opposite direction that reduces rpm for the compound..

  You can see built as oune complete body but don't have to tell you this
  is all very modular with gear box housing and shaft housings as
  separate..

  All gear ratios and dimensions will adjust obliviously according to
  design load and clearances..Certainly supported on the ends for rigidity
  as well...

  Jim talked about getting the turbo close to the exhaust port and also
  keeping the compound shaft in perfect alignment outboard, this may be a
  solution....


  Be nice, I am very sensitive as you know...

  jeff


 No jpeg attached??????

 jeff

 Sorry Jeff. I think you are gearing it up and not
 down.

 Paul Lamar

Jeff, Although I haven't done the CAD work on this I did research to find
out what type of system to use. There are manifolds allowing substitution of
one large turbocharger on a 13B which  is thought to extract more power than
the two stock turbines which are limited in size due to the tight spacing.

Although you could connect two hot side turbines with an inconel coupling
that is a really harsh environment and temperature expansion has to be
considered.  The major problem with turbo compounding is the 12 to 1 speed
reduction needed to connect back to the engine shaft. This is done with a
traction drive by rotrax or more commonly with multistage spurr gears by
procharger. To put these off the shelf items together the shaft of the
turbo supercharger would have to be replaced with one slightly longer and
providing a coupling for the procharger gearbox. Also  needed is a bearing
housing fabricated to fit the compressor air horn inlet with the opposite
end adapted to the procharger gearbox. As with your model above the engine
drives the compressor at low speed and the exhaust  turbine drives
everything at high speed. A waste gate is still needed in case the gearbox
becomes disconnected from the engine shaft.

         I have seen an advertisement on the Internet for an assembled unit
incorporating these design features as a kit for isuzu engines which is
available only in Japan. The compounded supercharger is built by
rotrax and manufactured  in Holland.  I couldn't get any information from
rotrax or a price. There is apparently only one size and I don't know the
displacement of the isuzu engine it is used on or the amount of boost.

       The shaft seems like a great excuse to use your CNC lathe. There are
steps, precision journals, tapers, and threads. It would also seem that
splines for a coupe ling might be necessary since it runs at 100K RPM.

      The torque of the high speed shaft should peak under 30 ft lbs at
start up and  fall to 7 ft lbs at full speed. I like the one large
turbocharger because it can  have a larger diameter shaft which would be
better to adapt a coupling to.

        One question about your design above. Are you gearing down to the
drive shaft then gearing back up to get a different speed  on the compressor
than the exhaust turbine rather than having them run 1 to 1 ?

george grimes

Doug Fir has a rotrex George.

Here is some info. I am using the same friction gear box in my design.


Paul Lamar