Tracy,

After looking back through my cooling calcs, the one other piece of info that is an assumption is the Velocity at the cooling inlet. The two assumptions that I have had to make are the ratio of the inlet velocity to the free stream and the temperature rise across the cooler. Turns out I was very conservative on the delta T. I used 80 deg F. Looks like you are getting a lot better than that. I did calcs for a range of Vi/Vo from .5-.9 . It makes quite a difference and is somewhat installation dependant. I'm guessing you are getting mostly external diffusion. So we should be able to get some idea of the radiators resistance to flow.

Which duct are you measuring? The one with just the evap core or the split duct with the evap core and the oil cooler?

Monty