Overshadowing these dealer modified Camaros was the factory Camaro ZL1. Specially designed to compete in the NHRA Super Stock drag classes, Chevrolet made it an option under the COPO system (code 9560). The cars began as SS396/375bhp Camaros with the F41 suspension. The SS trim and engine were deleted, and the 427 engine, cowl-induction hood, front disc brakes, a choice of heavy duty 4 speed transmissions or Turbo Hydra-matic, and a 4:10 posi axle were added. But instead of the regular iron-block and head L72 found in the dealer installed Camaros, the ZL1 sported aluminum heads and the first aluminum block ever made by Chevrolet. It shared the L88 aluminum head/iron block's engine rating of 430 bhp but made closer to 500 bhp -- making it probably the most powerful engine Chevrolet ever offered to the public. And the engine weighed just 500 pounds, the same as Chevy's 327 small block. The car was blessed with a 5 year/50,000 mile warranty and was fully street legal. With factory exhausts and tires, it turned low 13s; with headers and slicks, it could turn 11.6s @ 122mph. This was the fastest car ever produced by Chevrolet. Performance had its price -- $4,160 for the ZL1 engine alone pushing the price of the Camaro ZL1 to an unbelieveable $7,200 (about double the price for a SS396 Camaro). Chevy needed to build 50 to qualify the car for racing, and in the end built 69 Camaros and 2 Corvettes with the ZL-1 engine. Their high price made them difficult to sell and at least 12 engines were removed and about 30 cars were returned back to Chevrolet. It took until the early 1970s to sell them all. One can only wonder what they are worth today.