> It just occurred to me... I wonder if they can get quick light-off of
    > the catalytic converter with a couple of turbochargers in the way
    > absorbing heat.  Maybe the wastegate will be mandatory for that
   reason -
    > to get hot exhaust directly to the cat?
    >
    > On the flip side, having the turbos in the stream may give a
   little more
    > flexibility on the mixture side without overtemping the cat(s).
    >
    >
    > Matt-

   To solve the problem of quick light off, what if we put the catalytic
   converter inside the turbocompounder?

   from HowStuffWorks.com:

   "In the catalytic converter, there are two different types of catalyst
   at work, a reduction catalyst and an oxidation catalyst. Both types
   consist of a ceramic structure coated with a metal catalyst, usually
   platinum, rhodium and/or palladium. The idea is to create a structure
   that exposes the maximum surface area of catalyst to the exhaust stream,
   while also minimizing the amount of catalyst required, as the materials
   are extremely expensive."
   (http://auto.howstuffworks.com/catalytic-converter2.htm)

   Since catalytic converters structure is made of ceramic, we make the
   turbocompound wheels ceramic.  Mitsubishi is already doing that in their
   turbochargers.

   Then we plate the first ceramic blades with the metal catalysts: the
   platinum, the rhodium and/or paladium.  That way, they get the immediate
   blast of hot exhaust gases straight from the engine,  with no
   turbocharger blades in the way absorbing heat, because they _are_ the
   turbo "charger" blades.  No need for a wastegate and its associated
   plumbing to complicate heating the converter: the turbo _is_ the
   converter.  That way, the blades can quickly get to work catalyzing and
   turbocompounding.

   Now, I see that catalytic converters have more than one stage.  "The
   oxidation catalyst is the second stage of the catalytic converter. It
   reduces the unburned hydrocarbons and carbon monoxide by burning
   (oxidizing) them over a platinum and palladium catalyst. This catalyst
   aids the reaction of the CO and hydrocarbons with the remaining oxygen
   in the exhaust gas." (Ibid.)

   What if we split things up?   Catalyze the exhaust in the most efficient
   way:  either put the reduction stage in the turbocompounder, while
   leaving the oxidation stage downstream, or the other way around.
   Whichever part of the catalyzing most needs the immediate heat from the
   engine, put that stage in the turbocompounder.

   By putting at least part of the catalytic converter in the
   turbocompounder, we make things simpler, lighter, "cleaner".  :-)

   Or have I just outline another multimillion-dollar "garage project"? :-)

   What do you think?

   Les Nordman :-)

   Might work and be OK for Mazda and the EPA.

   We don't need it for aircraft.

   I also think you can heat the cat with an electric heater until
   the engine warms up.

   Paul Lamar ...No rotor no motor.



I also hear you Paul..  No cat needed on the airplane.  But...

I posed the idea a while back that having a cat between the engine and
the turbo might liberate even more energy to the turbo - or at least be
a wash - given the back pressure.  The additional combustion of the fuel
should cause increased gas flow - energy..  If one turbo catalyzed for
free (no restriction or added heat), the next one could pick up the
liberated energy.  Could help the BSFC a bit.


Matt-

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