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From: "Gary Casey" <glcasey@adelphia.net>
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Subject: diesels
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<<Any thoughts on whether all air cooled and/or water cooled diesels will
require big, ugly air scoops added?>>

As a rule of thumb diesels reject more heat to both the coolant and the oil
than do spark-ignition engines.  Also, the differential temperature between
the ambient air and the "coolant" is less - the air-cooled cylinders are at
maybe 350 degrees and the coolant is at about 200.  In theory then it takes
about a 20% lower mass air flow rate to cool an air-cooled spark ignition
engine than a liquid-cooled diesel.  Because the air-cooled cylinders are so
poorly optimized for air flow and the radiator is so well optimized the
pressure drop across a radiator is likely less than across an air-cooled
cylinder.  All that means that given enough space (where would that exist on
a Lancair?) the resulting cooling drag of a liquid-cooled engine COULD be
less than for an air-cooled engine.  I think you would be lucky to break
even.  Bottom line is yes, you may need a bigger scoop, but an ugly one?
That's in the eye of the beholder.  I think the ES cooling inlets are
oversize to begin with, but that's just a guess so far.

Gary Casey