Test 1: Adding The DriverObviously, you can't run without a driver, so I put on my helmet and climbed into the car. The sensation is very strange. The engine is not running and you're obviously not moving, but the wind around you gradually increases until you're buffeted around like you're actually on the lakebed. It's weird. Adding a helmeted driver reduced the horsepower drag from 551 to 547 hp, and the front lift was reduced by 30 pounds while the rear lift was increased by 10 pounds.
Equivalent horsepower increase: 4.Conclusion: Keep the driver.
Test 2: HoodscoopWhile it looked kinda cool, the hoodscoop was no doubt doing more harm than good, and the next test proved it. Blocking the scoop off completely with racer tape reduced the drag horsepower by 8. Removing the scoop altogether and filling the hole with cardboard reduced drag another 8 hp. It was obvious that the airstream was directed over the top of the scoop due to the shape of the top of the '32 Ford grille shell. Meanwhile, front lift was reduced by 30 pounds with the scoop blocked and 50 pounds with it removed.
Equivalent horsepower increase: 16.Conclusion: Trash the scoop.
Test 3: HeadlampsThe SCTA rules call for 5-inch-diameter headlights mounted outside the vertical edges of the grille and between 18 and 24 inches above the ground, measured to the centerline. Peter had made some rotisseries (variable mounting plates) that bolted to the So-Cal headlight mounts and could be used to rotate the headlights backward and forward and from side to side. Moving the headlights out, away from the grille shell increased the drag horsepower by 5 but reduced front lift by 17 pounds and increased rear lift by 2 pounds. Overall, a drag horsepower reduction of 2 was found.
Equivalent horsepower increase: 2.Conclusion: Mount 5-inch headlights close to the grille.
Test 4: Moon TankBecause the rules are so specific about the size and location of a front-mounted tank, we felt that some significant improvements were to be found by installing one. And even if it was just a catch can, it would look cool. Unfortunately, when installed, the tank increased drag horsepower by between 2 and 3 hp depending upon position. It also increased front lift by between 20 and 30 pounds. Peter surmised that the tank created a large and turbulent wake behind it causing drag and lift.
Equivalent horsepower increase: -7.Conclusion: Forget the Moon tank.
Test 5: Inner Front Wheel DiscsThe SCTA rules don't say anything about front brakes, but as this is a street-driven roadster, it has front brakes-big ones. We figured that if Moon discs are good on the outside, then something similar on the inside would be equally beneficial and might hide the brakes from the air. Fitting cardboard front wheel discs around the existing brakes resulted in a reduction of drag horsepower of 5.
Equivalent horsepower increase: 5.Conclusion: Lose the brakes and use inner wheel discs.
Test 6: Tonneau Cover And WindshieldThe issue of the tonneau cover and windscreen was not one that had been given much thought beyond the bother of retaining the stock Model A "eyebrow" between the windshield-post mounting brackets (stanchions) and the stanchions themselves. But that's a rule so you have to deal with it. The first step was to install a new cardboard screen that was taller and continued along the sides of the rollcage. Drag horsepower was reduced by 10. Front lift was unaffected but rear lift was reduced by 30 pounds for a significant improvement.
Next we installed a tonneau cover that came off the top of the eyebrow and had a positive top curvature rather than the standard negative curvature. Given the materials available, the cover joined the body smoothly with no gaps and overlapped the front. This reduced drag horsepower by 10 and front lift by 10 pounds.
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