Packard didn’t invent the straight-eight engine, of course. The cylinder layout is obvious, natural, and nearly as old as the automobile itself. But it was a signature Packard feature for decades, starting with the 1924 Single Eight and its innovative two-plane crankshaft design. (Read about the Single Eight here.) While the automaker on East Grand Boulevard also offered a fine inline six and a mighty V12 Twin Six, among others, the inline eight was Packard’s most popular engine through most of the company’s history.
Through these years, most of the Motor City’s automakers, from Buick to Hudson, also offered straight eights in their premium car lines. (Cadillac and Ford were two rare exceptions with their V8s.) But by 1954, only two straight eights remained in the American car market: Packard and Pontiac. And for 1955, they were gone, replaced by the ubiquitous overhead-valve V8.
With hydraulic valve lifters, a Carter four-barrel carburetor, an aggressive (for an L-head) compression ratio of 8.7:1, and better than 200 horsepower, the mighty Packard straight eight was, on paper at least, a competitive match with the new and advanced V8s from Cadillac, Chrysler, and the rest of the industry. But in truth, the Packard eight was at the end of its development life, and the high-compression V8s were only beginning to show their potential. For the 1955 car season, Packard retired its inline eights for good and introduced its own overhead-valve V8.