The original Z/28 was introduced in December 1966 for model year '67. It was the brainchild of Vince Piggins, who wanted to create a race-ready Camaro that was superior to the Mustang. So he took a a 327 block and put a 283 crankshaft in it so that it had a 4-inch bore and a 3-inch stroke, making it a 302.4 cubic inch, which fell just under the 305-cu.in. limit of the SCCA Trans-Am category. Its nameplate came straight from the RPO codes, RPO28 being the Special Performance Package. It wasn't mentioned in sales materials, so only 602 were made in the first year of production.
With the second generation Camaro, the Z/28 got a new engine as well. The 350 cubic inch LT-1 had 360 hp and 380 lb·ft. The greater torque and less-radical cam coupled with the Holley four-barrel carb permitted the Z-28 to be available with the 3-speed Turbo Hydramatic 400 automatic transmission as an option to the four-speed manual for the first time. In 1971, the power was down due to compression ratio decline. Despite selling more than 13,000 units in 1974, Chevy discontinued the Z28 (the "/" disappeared in 1972) due to tight emission regulations.
The Z28 was reintroduced in the spring of 1977 as a 1977½ model after Chevrolet have seen how many Trans Ams Pontiac could sell. The 350 V8 now only did 185 horsepower (or 175 if you lived in California), but since people were going for air-conditioning and the automatic box, this only bothered the most hardcore buyers. With various options, the new Z28 could be just as fast as its ten year-old relatives. No matter, Chevy set an output record, and outsold the Mustang for the first time.