Oil Drop Flow Test on the Cowl
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I wanted to show some pictures of the oil drop flow test I did on the cowl.  You will notice almost no air movement on the flat surface near the prop extension.  Some could argue that the flat area on my cowl prevents air movement, but I would think the prop would cause some rotation of air.  It doesn't happen.  

I wonder if the air at the lip of a normal cowl reverses direction, restricting the outlet of a normal cowl opening. I have exceptional cooling, and the outlet area is very restricted with exhaust pipe in the center of the eductor.  It might be possible I am getting an augmentation effect.    It would interesting to measure the pressure in this area of a standard design....  any takers?

Here is Terry Schuber's analysis of the pictures:

 Plain clean white paint near the crankshaft opening doesn't necessarily mean there is no air movement. It means the air is completely separated.
The flow lines headed toward the oil cooler inlets are straight and thin (attached and moving fast).  Then they get wider (slowing down) as they get closer to the oil cooler scoop.   Finally there is just clean white paint .  The velocity has dropped so much the air separated from the inlet.  The inlet air doesn't have enough pressure  to penetrate the cowl's pressure (hasn't expanded) so some of the fast moving ambient air just by passes the scoop and never enters the cowl.
Your inlet separation isn't bad but could probably be helped if all the inlets had rounded lips and a larger expansion area aft of the inlet opening. A boundary layer diverter on the oil cooler scoop or probably better to have the scoop attached to the cowl skin instead of out away from it would reduce drag too.

Terry has been a leading developer on drag reduction and I value his opinion and guidance this such esoteric subjects as tea leave reading, astrology, and oil flow insight.  THANKS Terry for you wisdom.... :-)

Engine inlets

Fuselage Sides,  Notice the separation just aft of the fuel sump.

Gear legs, notice the separation just aft of the gear leg fairs because I do not have
a clean transition from the gear leg to the fuselage.

Oil cooler inlet.

Bottom Cowl area, notice the little air movement near the prop extension and the separation where the cowl clears the starter ring gear. 

On the aft end of the cowl just above the eductor the oil lines are nice and straight.  Right next to the eductor outlet,  the oil flow lines just dribble down the cowl showing the extent of the air separation.