Here we've got an engine that The General has been building for more than 50 years (if you count crate motors), and which powered some of the all-time wildest machines during the Muscle Car Era.
This engine was born as the W Series in 1958, with 348 cubes of displacement, a weird combustion-chamber-in-cylinder design, over 650 pounds of mass, and one of the best names ever applied to an engine: Turbo-Thrust! By 1961, the General bored and stroked the W out to 409 cubic inches, dropped it in Bel Airs, Biscaynes, and Impalas, and achieved immortality with the song that might just be the Most Overplayed Car Show Song In All Of Human History:
By 1963, GM had installed some more traditional wedge heads on the W, resulting in the "Mystery Motor" seen with Smokey in the photo above. The 396-cubic-inch street version of the Generation 2 big-block debuted in 1965, a year in which purchasers of full-sized Chevrolets could choose between the 409 and the 396. From that point on, 396s, 427s, and 454s were getting dropped into every tire-charring hoonmobile under the sun, a process that continues today. The 1970 LS6 was rated at 450 horsepower, but that number was just a ruse to fool the insurance companies. The last GM car to get a big-block Chevy from the factory was the 1976 Impala/Caprice with the 454 option; big-block-powered trucks continued to roll off the assembly line until 1995. Nowadays, you can march right into your friendly GM dealership and leave with a 572-cubic-inch monster that makes 520 620 horses on pump gas. It's big, it's heavy, and it's crude, but it gets the job done and keeps going forever.