<<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
          <<  Lancair Builders' Mail List  >>
          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
>>
Hi Jon,  I saw your question back to George about the cause of the LOP
roughness.  The answer is that the forces on the crank are different between
cylinders due to mixture variation as the charts imply.  At a constant rpm,
the engine vibration due to rotational imbalances don't change regardless of
power settings and the combustion pressure is obviously uniform throughout
the cylinder once the flame front has progressed through the charge (happens
very quickly for our purposes).  To test this explanation, consider the
extreme case of roughness being when one cylinder doesn't fire say due to a
fouled plug.  That pushes the variation in force on the crank to the maximum
and you can imagine how that feels.

George, after reading your description of "the big pull", I'm still
wondering if the "forbidden zone" of mixture isn't just a relative issue.
Some guys on this list are reporting excellent cylinder cooling and claim
CHTs below 350 degrees in cruise (what mixture settings, I don't know).  If
CHTs are low at 50 degrees ROP, isn't everything OK except that they would
be be better at 50 degrees LOP?  Like Jon, I'm looking to make sure I
understand the relationships properly here.

Ed de Chazal
Rochester Michigan


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
LML website:   http://www.olsusa.com/Users/Mkaye/maillist.html
LML Builders' Bookstore:   http://www.buildersbooks.com/lancair

Please send your photos and drawings to marvkaye@olsusa.com.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>