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From: "Gary Casey" <glcasey@adelphia.net>
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Subject: Re:  FADEC Rough idle explanation
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<<Posted for "George Braly" <gwbraly@gami.com>:

  Want to try to define a list of what you think will be "better"  and why
  with FADEC than it will be with a well managed conventional engine?>>

I'm not an expert in Continental's version of FADEC, but I think if one
looked at the generic possibilities of a "good" FADEC system it would go
something like this:

  Hp ? - no difference as the spark timing of a conventional system is
probably about right for best power and the mixture was set for
cooling/detonation so nothing can be done there (not not always true).  The
Lycomings have a venturi that restricts the flow, so a speed-density system
would have slight advantage there (up to 3%).

  BSFC ? - I think there would be an advantage to the FADEC, but only at
high altitudes/low MAP when the standard system can't advance the spark.

  CHT ? - no significant difference that I can think of.

  Price ? - Any FADEC system will almost certainly cost more.  Maybe quite a
bit more.

  TBO ? - There might be no difference as while the electronics can be
expected to last forever the injectors won't.  The conventional system can
be rebuilt any number of times.

  Weight ? - If a distributorless system is used the FADEC will almost
certainly weigh more as multiple ignition coils probably weigh more than
one.

  Other ? - The primary advantage of a FADEC system should be idle quality
(title of present thread not withstanding) and starting, as well as reduced
pilot workload.  How important are those things?

Gary Casey