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From: George Braly <gwbraly@gami.com>
To: "'lancair.list@olsusa.com'" <lancair.list@olsusa.com>
Subject: RE: Engine dynamics - fuel injector air flow
Date: Wed, 6 Feb 2002 23:26:39 -0600 
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          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
          <<  Lancair Builders' Mail List  >>
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>>



<snip>
" As we have found, there us an affect from the air flow and 
pressure at the injector body itself.  Current in flight tests shows this 
to be especially true at cylinder 2.  By simply blocking the direct
high-speed
air to the number 2 injector, that cylinder is no longer the first to 
peak  nor to run 200-300 EGT degrees leaner than the others."


There is special hardware available for experimental users made by GAMI
(adapted from turbocharged nozzle arrangements they make) that can be
installed on experimental aircraft to eliminate this effect which is
sometimes seen on the higher speed engine/airframes.  GAMI first observed
this on an IO-720 Lycoming installation done about three years ago.  

The effect is most pronounced at number 2 on the Lycomings, but is present
to some degree.  If the baffling design is done with an extended prop so
that the airflow has chance to expand and slow down inside the cowl area,
the problem is not as significant. 

However, even when you completely eliminate this effect (i.e., by, for
example, hooking up a common upper air duct plumbing arrangement - -such as
the turbo systems have) to the nozzles, the Lycomings still have a rather
poor F/A ratio uniformity that needs to be fixed.

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