Does anyone have any data about how fast the EGT drops with distance
   from the exhaust port?


   Regards,

   Matt-

   Back in the archives some where there is some data from Mistral on
   that as I recall.
   How bad do you need it? It is really a function of P-exhaust port
   verses side exhaust port.
   --
   Paul Lamar ...No rotor no motor.

Has this been discussed before?


http://www.ststurbo.com/universal_system
<http://www.ststurbo.com/universal_system>

This is akin to a P-47 turbocharger - mounted a significant distance
from the exhaust port.  Obviously this concept would only work on some
airframes.

My thinking is that mounting the turbocharger 5ft from the exhaust port
will allow the exhaust more complete combustion, and significantly lower
the EGT seen by the turbocharger - allowing a cheaper set of wheels.  It
also would free up significant room in the cowl, and make intercooling
easier.    Might be quieter too.

Obviously there are downsides:

- custom airframe mods - not firewall forward.

- possibly worse thermodynamic efficiency - a wash given more complete
combustion.

- turbo lag - don't care as long as it doesn't cause surging - an
automatic waste gate controller might be challenging.

- much longer section of exhaust stack that can heat the airframe and
leak - fire hazard.  This is probably the biggie.  I'd say design a
metal line tunnel in the belly of the airplane, the length of which is
exposed to slipstream airflow.  I'd probably also incorporate one of
those old style exhaust cuttouts (bypass) like the drag racers run.  If
you detect an exhaust leak or turbo failure, open the bypass which
allows dumping the exhaust at the front end of the system - noisy by safe.

- weight of the stack - might be a wash compared to a muffler and a
turbocharger

- more complex oiling of the turbocharger.



Regards,

Matt-

We talked about it years ago. I was rather surprised the P47 installation was as efficient
as it proved to be.