I would like to assume that the designers knew what they were doing when they designed that big scoop on top of the cowl.
But I bet that more air leaves that scoop than goes in.
First, there’s a huge boundary layer problem on the upper cowl, and a spinning prop, turbulating the air only makes it worse. Second, I installed some “flappers” on the top cowl of our Glasair. I saw some guy do it at OSH, and thought it was a cool idea. (No pun intended.) They were simply hinged doors that dropped down via gravity, to cool the engine after shutdown. And, presumably, they closed in flight from a pressurized cowl.
Long story short, it took about 10 years of glazing cylinders during break-in, seeing too high CHT’s on climb out, etc. before I figured out that these flappers were actually opened in flight, depressurizing the cowl! (Impossible to see them in flight.) I glued magnets onto the doors so that they would snap closed and saw my CHT’s drop at least 25 degrees.