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UPPER GRILL BLOCK OFF PLATE
The front grill openings on older cars, and even modern designs, are sometimes pretty
massive - creating extra drag. The 1969 Camaro front end had all of the cooling air coming from a very large upper grill, as shown below. These large front openings were often deemed necessary to keep cars cool in the worst stop-and-go traffic, in the hottest climates, with air conditioning running on full blast.
This is what we had to start with - more in common with a truck than a sports car
More modern sports cars have gone away from large, open grills to more limited front openings. The most modern, aero inspired designs push the grills closer to the ground, and we're starting to see a few OEMs that even duct the waste heat out via massive hood openings (see the C7 Corvette, below). This is a trick that can be packaged in new designs to create some extra downforce (or eliminate lift).
This is more what we're shooting for...
One of the things I mentioned that we've tested (from previous track testing and splitter work) was blocking off the large, open upper grills from a typical "flat front end" car, like the 1st gen Camaro or the modern Mustangs and Camaro coupes.
Since this 69 Camaro is being built primarily for track use we're going to cut down some drag and force high pressure air where it can do more work - to a newly created lower grill opening. Blocking the upper grill puts more air through this smaller lower opening, right above the splitter, which in turn helps create downforce. This is amplified when the air has a better place to exhaust - through massive, ducted openings in the hood placed in the right places. That's another big part of this project we will will expand upon in later posts.
And there is a lot more than just "making a lower opening" - there has to be inlet ducting sealed to the front sheet metal and to the heat exchangers, to force air through instead of around the radiators. The images above show that on our shop Mustang - with the front end removed you can see the duct boxes and routing of air from the lower grill.
For this car Ryan first took the new OEM style, reproduction, plastic 1969 Camaro grill and made templates in cardboard to block the back side openings completely. The goal is to keep the "look" of a stock 69 Camaro SS grill, but with aluminum sheet mounted behind it keeps the airflow through the upper opening to "zero", forcing more air over the hood or towards the lower grill opening - and reducing drag. It won't be as effective as the smooth grill plate we did on the Mustang shown above, as the protruding plastic mesh grill in front of the block off plate will add a
little drag, but its the best compromise between looks and performance.
The templates were turned into four portions of aluminum structure, with the two middle sections welded together. The outer sections bolt onto the back of the grill, outboard of the headlights (which have a bit of airflow normally). The two conjoined inner portion bolts on to block out the majority of the middle grill surface, with a near air tight seal to the plastic grill structure.
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