How much does a hood scoop actually help?

threewood said
Cooler air charge is about the only benefit from a stockish scoop. In order to get ram air effect the scoop needs to be up in the air stream, a 6 pack scoop is not tall enough from my research. I would seal the cleaner to the underside of the hood.

Here is my solution to seal it. I ordered an 18" aluminum baking pan, cut the center out, riveted the cleaner base to the pan. Added a push-on bulb seal to the rim. Added a Wix 4" tall filter. Better than sucking in hot air.

Hellrats said
This is one awesome idea!!!

I want to add just a little to this discussion, and maybe just a slight difference in the aluminum pan idea. (which is what I am also doing)

I have a scoop about 3" tall with the opening about 2/3 toward the front of the hood and I can tell whoever wants to know that air does not get forced in when driving.
When I drive in the rain I get a couple of small water spots on top of my air cleaner cover, but that's about it and I have driven in rain so hard that you couldn't do over 25mph and see in time to stop for anything stopped in front of me.

Hot compartment air definitely is sucked out instead of cold air forced in.
(Plus it cools the compartment a little quicker when stopped)

That said, when I do the aluminum pan and seal it to the hood for the cold air intake effect I am going to add a 1/4 drain tube to the back of the pan and run it down the back of the block just in case.

If it's raining hard and I'm parked on a nose up incline I don't want water running in and pooling in the pan.
The 1/4 drain won't make much difference at all as far as intake charge temp goes, but it sure will make a difference if water does happen to get in.