Chevy’s Mark IV engines roared into the automotive scene with a bang, featuring a variety of big-block beasts. The 396-cubic-inch version made waves in the Corvette and Chevelle with its 375 hp output, while the 427-cubic-inch monster, available in the Corvette and the unassuming Biscayne, delivered neck-snapping performance. Dubbed the Bisquick, the Biscayne transformed from a taxicab lookalike to a speedster with 425 hp. Even with aluminum heads reducing weight, these engines proved old-school horsepower ratings were more optimistic than realistic.