Mark,
<< ... air .... was actually backing-up at the inlets.>>
While all inlets will vary, some portion of the pressure recovery occurs in front of the inlet due to this "backing-up".  The velocity ratio of the inlet will tell you how much air is flowing through relative to the free stream velocity.  The lower the velocity ratio, the more air is backing up in front of the inlet.  For a given installation, increasing the inlet diameter will lower the velocity ratio.  
A good discussion of cowl inlet design can be found in NASA report CR 3405 starting on page 39. http://www.n91cz.com/cooling/Copy_of_NASA_Cooling_Report.pdf

On my 360 the oil cooler is also fed from the air entering the main inlets with the oil cooler exit throttled down to about 5 in^2.  


Chris Zavatson
N91CZ
360 std.
www.N91CZ.com