Al Gietzen wrote:

In a recent exchange about engines on our Velocity builders e-mail list, one
happy Lycoming user states:

"Say what you will, a well tuned Lycoming will give a BSFC of .375.
That's about as good as it gets for any four-stroke gasoline engine.  There
is just no truth to the "Lycosaur" paradigm."

My reaction is "in your dreams".  But then I'm prejudiced. (Probably not the
only one on this list).  Anybody ever hear of a BSFC like this on a Lyc
4-cylinder?

Al Gietzen

No way. Particularly as Lycoming does not allow running lean of peak.
Too hard on their precious $250 each sodium cooled exhaust valves.

More like 0.45. 0.375 BSFC is turbo compound country.

Paul Lamar

Paul is correct, except that the valves cost more than $250 each.  Continental
charges more like $100 each for their valves, which appear to last about
as long.

 This claim what I call "science fiction" -- a whiff of science and a lot of
fiction.
0.375 BSFC can happen in diesels, but not easily, in the unusual Continental
Voyager series (very special engine) but no way in the world in a Lyc.

Lest you might think I disagree with the author totally.  He is correct.
There is no [fundamental] truth to the Lycosaur paradigm.  The basic
engine is a very light, powerful and durable engine that routinely survives
running a 75% of rated power and has as good a breathing as almost
any engine you could name, better than most, considering the low RPM
limits imposed by direct prop drive.  The normal auto motor (non wankel)
is extremely fragile, heavy and complex by comparison.  And will NOT
get 0.375 BSFC either.

Bill Freeman
Long EZ builder & pilot
BSME, MSME
EAA Technical Counselor

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