Overheating issues with remanufactured 360

The concern/issue is the while they may flow a lot of air, the shroud is so shallow that it makes at least half of the air that could come through the rad to make a sharp 90 degree turn. This truly restricts a lot of the air flow from the areas of the rad that are not directly in front of the fans; i.e., you are only getting good airflow through 2 10" diameter areas of the rad and some small areas around that, not the whole rad. Compute it out: That leaves you with maybe 150 square inches of rad area with good air flow (and I am being generous at that), out of a total flow area of over 300 square inches.

This limited flow area may be OK with a very low heat load (idle) but not at any higher heat load. 'specially with a 2 row rad. The stock setup with the smooth radiused shroud made sure that did not happen.

And at any speed above around 25 mph or so, the air flow from the car's motion becomes the primary air mover, not the fans. That car motion will move far, far more air through an open rad than any set of fans ever will, and the fans alone will simply not move enough air when you have any load (heat generation) in the engine. Additionally, the fan blades will actually block some of the externally induced airflow so that becomes even worse, and the above mentioned sharp turns in airflow will further restrict total flow. Again, look at the stock shroud and fans.

If you put 90 degree turns in an intake port, you would expect the airflow to the cylinders to drop like a rock; it will do the same for a shroud.