I believe there is a requirment that the engine must be able to operate
at rated power within allowable temps with only 50% of the oil sump
capacity. If so that might explain why sumps are seemingly "oversized".

Bingo.
33.39 (a) The lubrication system of the engine must be designed and
constructed so that it wil
l function properly in all flight attitudes and atmospheric conditions in
which the airplane is
expected to operate. In wet sump engines, this requirement must be met
when only
one-half of the maximum lubricant supply is in the engine.

Was their a timed limit for the test runs that proved the engine could
"function properly in all flight attitudes", or did they simply run the
engine until there was only "half of the maximum lubricant supply" left?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"