Sorry to come in so late on this, but we did do as much testing without a tunnel as we could. (2000 ?) The difference was amazing. We did use the yarn tufts, video taped at 30-50-70 and 100mph. Tufts were installed in the very front of the "Naca Duct" much like a Viper uses and on top of the Naca Duct. Tufts were installed in the very front of the rearward facing scoop, along the top and at the very back. Just for giggles we installed tufts about 4" apart on the lower windshield, the middle of the windshield and of course at the top.
What we found was amazing and good info. The tufts in front of the Naca Duct actually were sucked inward while the top tufts almost didn't move. The tufts at the rear of the scoop actually got totally sucked into the engine comparment ALONG with the tufts at the lower windshield area. The middle windshield tufts couldn't makle up there minds to go up or down into the intake. The upper tufts finally went up. The reduction of air pressure on the windshield was amazing in itself.
Bottom line, want more air into the intake with positive pressure and not a vaccum, turn the scoop around and no need to raise it higher.
Maybe the Kirkham group had something going there
DV
