[Grubby]

A scoop like on Cobras will actually have air pushing out from the engine bay at speed.

There is much more surface area in the nose than the scoop. Thus more air pressure pushing in the radiator than in the scoop.

If you have a turkey pan or some other method to seal to the bottom of the hood, then the hood scoop will do what you think it should. There is no opposing air pressure in this situation.

Most of the OEM muscle cars had air boxes that sealed to the hood.

John