Chevrolet’s 348, 409, and 427-cubic-inch “W series” engines look nearly identical from the outside, sharing interchangeable heads and the same basic block architecture — with one telltale difference: dipstick placement. Introduced in 1958 as Chevrolet’s first true big-block V8, the family climbed from a 250-horsepower Turbo-Thrust up to a 350-horsepower Special Super Turbo-Thrust before the 409 and 427 took over as the brand’s flagship big-blocks. Read on for how to tell these engines apart and where each one fits in Chevrolet’s horsepower history.