[aerohead]

Originally Posted by Christ

I said nothing of a roof... and that post was meant for a car more like basjoos' Civic, where there probably isn't as much pressure build up at the nose, but likely still a nominal high pressure area at the base of the windshield.

Ducting air through the hood is not a new concept, the 1990 Z24 Cavalier uses hood ducting for induction from the ram scoops on the hood. (yes, they're functional)

What I had mentioned was to take the pressure from the high pressure area at the top of the hood/base of the windshield, and vent it through the hood, back to the radiator, which does not disrupt aero at all.

Also, in the case of basjoos' Civic, which obviously doesn't allow alot of air through the front to the radiator, the engine bay would be a significantly lower pressure area than even post 11's diagram shows, meaning that it would be OK to vent that windshield pressure to that area, and could possibly create a slightly different aero profile for the car.

The only downside, other than complexity, that I see to the whole thing, is that if there is no high pressure area in that "crook" where the windshield is angled, flow will have a higher tendency to attach there, and may actually hurt the aerodynamics of the car, by causing more drag.

Without seeing a diagram of this modeled, I couldn't tell for sure.

If you pull that kind of volume of air from the windshield area you'll cause separation over the roof.If anything you want to eject air at this location.This is what Kamm did,and its what made his K-Car work.You'll never see a car with this and there is a critical reason for it.