The Last Straight-8 Engines Built By American Car Manufacturers

Modern automakers tend to favor a small number of highly popular engine formats, such as the inline-four, inline-six, V6, or V8. However, over the course of automotive history, and especially during its first couple of decades, automakers have employed a wide variety of weird and wonderful engine designs, with varying degrees of success.

One often-forgotten type of engine, which went from a peak of popularity in the inter-war period to a rapid decline in the 50s, is the straight-eight. Frequently associated with Bugatti in Europe and Duesenberg in the US, the straight-eight was, however, also used by other car manufacturers which have a stronger connection with the modern era. Here is the story of the straight-eight engine and the last American carmakers that continued to hold onto it until the very end.

Where It All Began: The I8's Early History

The origins of the straight-eight engine lie in a prototype that never saw the light of day, designed by a small French firm at the dawn of motoring history. Charron, Girardot et Voigt (CGV), headed by a trio of early car enthusiasts, was responsible for the design of a 7.2-liter straight-eight that never made the jump from design to production. Later on, as technology progressed, the first working straight-eights began to appear in planes, rather than cars. Daimler used one of its six-cylinder units as a base to build the D.IV straight-eight engine, which powered World War I aircraft for a limited time before being replaced due to poor reliability:

After the end of the war, the straight-eight began to be used in the automotive world as well, with the Italian Isotta Fraschini Tipo 8 being the first production car to be powered by one. The straight-eight’s popularity grew rapidly, with automakers in the UK (such as Leyland with the Leyland Eight) and the US (most notably Duesenberg) introducing models that sported a straight-eight under the hood.

The Straight-Eight's Inter-War Heyday

The 1920s and 30s represented the peak of the straight-eight’s popularity, both in Europe and in the US. On the other side of the Atlantic, Bugatti built a strong association with the straight-eight, using this engine type to power several of its models including the legendary Type 35 race car. Bugatti enjoyed a good degree of motorsport success in the 1920s with the Type 35, which claimed a Grand Prix world championship and several other victories.

The straight-eight was also popular in Germany and Italy: Daimler made good use of its previous experience building straight-eight engines for wartime aircraft, and started building automotive straight-eights to power the Twenty-Five, Thirty-Two V 4 ½, and the E 3 ½. Over in Italy, the 1931 Alfa Romeo 8C also sported a straight-eight under the hood. Meanwhile, in the States, high-end marque Duesenberg was most commonly associated with the straight-eight, making use of this layout in all its production models (the Model A, Model X, and Model J). The Model J’s engine was produced by aircraft company Lycoming, which had expanded into building engines for the automotive industry.

Lycoming’s owner, Errett Cord, also used this straight-eight in some models produced by his other companies, Cord and Auburn. Duesenberg would not survive the Great Depression, but its historical connection with the straight-eight engine is still known today.

The Last Survivors: Straight-Eights In The 40s And 50s

At the start of the 1950s, a handful of American automakers were still producing vehicles with straight-eight engines. Here are the big names that continued to produce straight-eights the longest:

Pontiac

The Pontiac straight-eight was produced between 1933 and 1954; its main claim to fame at the time of its introduction was being the least expensive eight-cylinder engine built by an American manufacturer. The straight-eight was available as an option in Pontiac’s lower-end models, and as standard in the higher-end ones. It was given the nickname Silver Streak, after a design detail specific to Pontiacs from that era (a chrome band down the middle of the hood and trunk). Power outputs ranged between 77 and 127 hp. In 1955, the Silver Streak was replaced with Pontiac’s new naturally aspirated V8 engine, the 287; this marked the beginning of Pontiac’s image shift from budget-friendly to high-performance brand.

Oldsmobile

The Oldsmobile straight-eight was produced from 1932 to 1949, and was the company’s top choice of engine throughout the '30s and '40s, powering models such as the L Series. Power outputs were relatively low, in the range of 85-110 hp. Eventually, the Oldsmobile straight-eight was replaced by a V8 (dubbed the Rocket V8 as part of the brand’s Space Race-inspired image) at the end of the 40s. The arrival of the Rocket V8 also helped bring about the early beginnings of the muscle car era: the Rocket 88, released in 1949, combined V8 power with a lightweight body and aggressive looks, creating the blueprint for the golden age of muscle cars.

Chrysler

The Chrysler straight-eight engine was produced between 1930 and 1950, powering models such as the DeSoto, Imperial, and Saratoga. This engine was also used in several Dodge models, including the Series DG and Series DK. Several different varieties of the Chrysler straight-eight were available, with power outputs ranging from 70 to 150 hp over the decades. The last straight-eight engine ever produced by Chrysler was a 5.3-liter unit, which powered the Saratoga and the New Yorker; it had a power output of 135 hp.

Buick

Buick’s straight-eight engine, dubbed the Fireball 8, was produced between 1931 and 1953; power outputs ranged between 75 and 120 hp. It was originally designed as a replacement for the Buick straight-six, which had powered the brand’s pre-1931 lineup. When the time came for the straight-eight to be replaced, Buick took a staggered approach: starting in 1953, all models received the new Fireball V8, while the budget-friendly Buick Special had to wait another year for the powertrain update.

Packard

The last American production straight-eight engine was built by Packard, a now-defunct luxury car company based in Michigan. Packard’s straight-eight enjoyed a thirty-year production run, from 1924 to 1954. A wide variety of straight-eight engines were produced by the company, with power outputs varying between 109 and 212 hp. The same year the final straight-eight rolled off the production line, Packard attempted a merger with Studebaker to reverse its poor financial fortunes, but the operation was not particularly successful and the Packard name disappeared for good within five years.

Why Did The Straight-Eight Disappear, And What Replaced It?

The rapid disappearance of the straight-eight came about due to the mechanical disadvantages it experienced, its impracticality, and the emergence of more powerful, efficient engines such as the V8. Due to the very nature of its design, the straight-eight was structurally unstable, with high levels of vibration and a long crankshaft that handled stress poorly. This was less of a problem during the straight-eight’s '20s and '30s heyday when engine revs were low. In the '40s, however, wartime technological advances spilled over into the automotive industry, and it became possible to build engines with higher compression ratios: the straight-eight was no longer a viable choice of layout, as it was too prone to breaking down.

Its dimensions were another issue: as the large, luxurious cars of the pre-war period gave way to smaller, affordable cars of the modern era, there was simply no room for a straight-eight engine. The long hoods of Bugattis and Duesenbergs were not compatible with modern car design, and automakers quickly switched over to more compact layouts, such as the far shorter V8, which rapidly exploded in popularity. By the mid-'50s, all the last American brands which were still holding on to the straight-eight had moved on to alternative engine layouts, and the straight-eight was officially consigned to the archives of automotive history.

Sources: EngineLabs, Silodrome, CaroleNash.com, Museo Storico dei Motori e dei Meccanismi.