Came across this point in the Hot rod magazine article about wind tunnel testing the Camaro that Cd pointed to:
Car Aerodynamics - Modifications - Hot Rod Magazine
Quote:
Seal the back of the hood to the cowl: This is another area that's less critical on newer cars that are already well sealed. Cowl-induction hoods have a high-pressure area at the base of the hood. Air does not travel out the back of the hood; it is forced down into the engine compartment. That air must escape through the car, causing flow disruptions and drag.
Improvement: 10-20 counts less drag, 50 to 75 in lift
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For comparison, they estimate a 15 to 30 count reduction with a full grille block.
(1 count of drag - Cd 0.001)
I believe this is the same kind of block Phil referred to in testing of his CRX streamliner at Bonneville:
Quote:
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A cardboard and duct-tape cowl fillet over the wiper area demonstrates a 0.28-mph improvement to top speed.
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Source:
http://ecomodder.com/forum/showthrea...drag-2888.html