The Beach Boys wrote a hit song about it, but Chevrolet’s 409 was only the public face of a much bigger story. Behind the scenes, a secret 427-cubic-inch “mystery motor” was quietly setting records at Daytona in 1963 while Chevrolet stayed silent about what powered it. Read on to find out how a handful of aluminum-bodied drag cars evolved into the 427 that would eventually power Corvettes, Camaros, and Chevelles for years to come.