Thread: Air flow
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Old 01-14-2021, 11:27 AM
Steve C. Steve C. is online now
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Join Date: Dec 1999
Location: Liberty Hill, Tx. (Austin)
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Tid bit from a magazine that might be of interest. And relates to Cliff's comments......

When designing a cold-air package, remember that an optimum entry will provide a nonturbulent air supply above atmospheric pressure. Front-facing hoodscoops typically begin supplying air at lower speeds, while rear-facing scoops supply air at higher speeds with less turbulence. Inside the scoop, all air ducts should be designed so that air entering the carbuertor will do so smoothly- preferably through a air cleaner or other diffusing device. Be sure that the bottom of the air cleaner's lid does not rest too closely to the top of the carbuertor where it will restrict air flow. You should leave at least 2 inches of clearance.
If your building your own scoop, make sure the incoming-air opening is at least 10-15 percent larger than the carburetor venturi size. This typically equates to about a 20- to 25-square-inch opening in the scoop. For optimal performance, the roof of the scoop should be placed about 2 inches above the carburetor. Be careful not to build the scoop too high because additional clearance can sometimes create turbulence. Adding a scoop to the carburetor system can also effect the air/fuel ratio of the existing combination because the incoming air will hold more oxygen molecules. As a general rule, you might want to begin your tuning by jetting up about two jet sizes (from prior optimum jetting) after you've added a cold-air package.

On another note.... and take this one with a grain of salt !

Very successful Pontiac Super Stock racer John Clegg stated that a front-facing hood scoop will work as a ram air source only if the car in question is doing 200 mph. He used a small Harwood scoop mounted backwards on the hood of his 8-second former record holding Firebird ( it looked like a large size Trans Am scoop ).


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