[Rhotpursuit]

The guy built a very nice custom truck, a ton of time spent I'm sure, I say well done. Okay sure he could have worked on some ducting to allow the pretty much worthless cowl induction Chevrolet added to the '70-'72 Chevelle running it into the airbox. Too bad this post went south.

I just never understood what the engineers were trying to accomplish, opening a vent a top the rear part of the hood where the slip stream is causing a vortex sucking out air. Well without seeing the wind tunnel results of such a door, I suppose it could cause a back flow at the angle change at the rear edge of the hood and the windscreen (windshield).

I'll keep the Ram Air setup on my '71 442 W-30.

You have no idea how a cowl hood works. When a vehicle is moving 15mph+, high pressure builds at the base of the windshield. Even with my "for looks only" cowl hood, I can tape a ribbon or two to the back of the hood near the vent. When I start driving, the ribbons flutter, then they get sucked to the vent opening.

 

[2MNYVHIX]

and exactly why I also said this "I suppose it could cause a back flow at the angle change at the rear edge of the hood and the windscreen".

Funny thing is I have the fiberglass part that is mounted under the exterior flip door on those Chevelle hoods. It's in a box in the shop somewhere, don't even remember where it came from.
Painted many Chevelle/ElCamino's back in the mid/late 70's-early 80's seemed everyone wanted those hoods. I fortunately worked in a shop that did high end work, show cars, restorations, hot rods and such when $3,000-$5000 was the price, now it's $60k to over $100k. I now work in aerospace, cad/cam stuff.