plus maybe you get some lift on the hood due to the air going in there?
Dunc
...Really ram air does not put much "if any" air pressure in there....Our ram air ports are not close enough "Nor high enough" to the front of the car to get a real ram air action...It is more like a cold air induction..
So no real air pressure gets in there in the first place...Now if our ram air vents where right on the nose..Or raised up much higher....then it would get some forced air...Our inductions are little tad better than a cowl induction.
Not correct, not even close.
NACA (National Advisory Committe on Aeronautics) deigned the shape of these surface-scoops for high-speed aircraft to increase air-flow into the scoop without inducing the excess drag that a typical scoop protruding from the surface would.
Chrysler conducted air-flow tests in the sixties and determined that the layer of stagnant low-pressure "lamainar" air basically surrounded and sealed-up the exterior surface of a moving vehicle. This lamainar air flow nearly prevents all air from entering any typical air scoop on the surface of a car.
Turbulent, high-pressure air is what you want, and that is found in basically four locations on a moving automobile: Under the front bumper, at the very leading edge of a fairly upright grille area, the base of the windshield and at the very tail end (trailing edge) of a short, high (truncated) trunk lid/tail end. This short and high design was the result of discoveries by the legendary Wunibald Kamm, an aerodynamicist/ auto designer, and is called a "Kammback" design. The GT-40s used this design effectively, and our 71-73 Mach 1s were designed to display this exact feature.
Scoops under the bumper are very effective (as in the earliest 442s), but also ingest road debris and water, making them none too desirable overall.
Leading edge of the hood scoops are effective, and several cars feature these: later 442s, 68 Shelbys (somewhat), etc...
Base of the windshield is an excellent area to grab some turbulent air, and the reverse facing cowl induction is effective, but only at higher speeds.
Chrysler's research led them to the hideous (but charming in its own way) snorkel or "mailbox" scoops seen on a few cars in the 60s/70s. These scoops did indeed get up above the "laminar" air flow, but increased dag sustantially. The snorkel protruding forwward once above the laminar layer is what prevented the laminar layer from simply enveloping the entire scoop. Crude but effective.
The NACA scoop is a wonder of air-flow management. The surface layer entry area of the scoop slowly ramps down into the scoop, and since nothing protrudes above the surface, there is no excess drag induced. The high-pressure, turbulent air above tpushes down on the lower low-pressure laminar layer, effectively sealing it to the cars body. As the entry area of the scoop drops away the high-pressure air pushes the low pressure air into the beginning of the scoop. As the walls of the scoop get taller, the scoop itself gets deeper and it volumetric area increases dramatically. The "walls" of the scoop prevent this air from bleeding out the sides, and the high-pressure air above creates a "ceiling" of air that prevents the low -pressure air from escaping above.
The walls also widen as they deepen increasing the Bernoulli-effect (venturi) simultaneously. As the "trapped", which has increased in pressure above ambient due to the higher-pressure air above it pushing it into the leading edge of the scoop air moves towards the rear larger, lower-pressure area of the scoop, the air molecules will now rapidly spread apart from one another, becoming quite energetic and turbulent...and fast moving.
Air molecules will always flow from high pressure to low pressure areas and therefore have nowhere to go but into the scoop, and at a much greater velocity than simple atmospheric pressure (14.7/1) would be able to introduce it. Thus the "ram air" effect.
When Ford put the scoops on the Mustang, it fudged a bit and simply renamed the scoops "NASA scoops", since everything "Space Race" at the time was so popular, and also because there was no NACA any more. NACA's name ws changed to NASA (National Aeronautics and Space Administration) in 1958 due to the increasing demands of space technology at the time.
These NACA scoops are used everywhere today, and on many vehicles...especially on the underside on belly-pans and skid plates.
They simply work amazingly well.
Now, after all that, I will say this:
There is no record or any documentation from Ford that I have ever seen that states that Ford did any actual real wind-tunnel testing on our Mach 1s during its development. The only wind-tunnel avaialable at the time was an aircraft company's (Lockheed, I think) and was very expensive to rent and could not be used fopr long periods of time. Chrysler used this tunnel and stopped after the costs became so exorbitant.
I strongly suspect that Ford simpy incorporated the design cues of aredynamics into thier styling without actually verifying thier real functionality.
The Kamm-back and the NACA scoops are two distinctive designs of our cars and both gave it a radically new and "leading edge technology" look when new.
Both of those features are in abundance on near every vehicle you see today, especially the Kamm tail. Nearly every passenger vehicle utilizes a relatively short trunK lid, with a relatively severe drop off.
