Kimberly V. Althage – May 6, 2022
Outside of serious NASCAR enthusiasts or classic car fanatics, the Superbird is relatively unknown, yet it is one of the wildest vehicles ever released. The short-lived Plymouth Superbird was a highly modified Road Runner, a low-budget but powerful mid-size car first introduced in 1968. Plymouth took a relatively standard-looking muscle car and turned the Road Runner into an iconic hot rod with superior aerodynamic capabilities making it a powerful competitor on the NASCAR circuit and one of the most influential muscle cars ever.
The Superbird was created for two main reasons. In an era of factory-backed racing when “what wins on Sunday, sells on Monday” existed, Ford was crushing Chrysler on the NASCAR track. Plymouth needed to dominate stock car racing and elevate their competitive credentials. The other reason was to lure “The King” back from their rival Ford.
Richard Lee Petty is also known as “The King.” He was a stock car racing driver for NASCAR Grand National and Winston Cup Series (currently known as NASCAR Cup Series) and was Plymouth’s star NASCAR driver. Although in the 1967 season, Petty won 27 out of 48 NASCAR races, the limits of his Plymouth Road Runner proved to be a handicap. Petty wanted to race under the Dodge banner due to these shortcomings, but Chrysler executives insisted he stay with Plymouth. As a result, Petty left the Plymouth NASCAR Racing Team for Ford’s in the fall of 1968. Petty won the very first race of the 1969 season and finished second in NASCAR’s Grand National points race. Panicked, Chrysler Plymouth knew it would take a more aerodynamic car to lure him back.
The first American car to be designed aerodynamically inside a wind tunnel using computer analysis was the Charger 500. Later it was modified into the Dodge Charger Daytona with its memorable nose cone and tail wing additions to improve its aerodynamics. The results were phenomenal, as it set a NASCAR record being the first vehicle to reach a speed exceeding 200 miles an hour. Dodge was Plymouth’s sister company and due to the Charger Daytona’s success in the 1969 season, Plymouth used their aero-body design as a base to create their own racing monster.
The typical muscle car of the era encountered a lot of air resistance from their square front ends which negatively affected track speeds. Engineers designed the Plymouth Superbird with the help of a wind tunnel and the expertise of former NASA rocket scientists. Gary Romberg and John Pointer were genuine rocket scientists working under Chrysler’s missile division. They and their team of engineers were on the cutting edge of innovation to develop a more aerodynamic car.
The Superbird was inspired by and incorporated several design cues from its sister car. Both famously feature a NASA inspired protruding, aerodynamically designed shark-like nosecone. The Superbird’s elongated and tapered nose added nineteen inches to the Road Runner’s original length and was more refined than the Daytona’s. The Superbird’s front “beak” cut into the air at a slightly higher angle than the Daytona’s. Although shaped differently, each vehicle’s nosecone and spoiler act to eliminate front end lift and reduce drag by limiting airflow under the car.
Another famously distinctive feature of these Mopar aero cars are their high-mounted rear wings. Each of these “Winged Warriors” had ostentatious rear spoilers mounted on tall vertical struts. The Superbird’s side stabilizer part of the wing was 40% larger than the Daytona’s. Contrary to the urban myth these wings were 23.5 inches tall to satisfy a NASCAR regulation that the trunk lid open freely, its true purpose was to provide clean air and keep its rear tires firmly on the ground at high speeds.
Not one thing is for aesthetic reasons solely — every bend, curve, and arch served a purpose. Such razor-sharp aerodynamic engineering makes the Superbird more aerodynamic than a modern Mclaren P1. The Superbird and its sister car were both engineered to cut through the air and generate enough downforce to make them the most agile and quickest vehicles on the NASCAR circuit. Although the Plymouths design changes made the Superbird substantially sleeker and provided greater downforce, their design was considerably less aerodynamically efficient than the Daytona. In fact, the Superbird was 3mph slower.
Superbirds had three engine options available for purchase. The menacing engine used in all the NASCAR races were top-of-the-line 426 cu in (7.0 L) Hemi big-block V8 engine. The Hemi powered the racing Superbirds with 433 horsepower and 472 pound-feet of torque. It could demolish the 60mph in a mere 5.5 seconds. Only 135 models in all were fitted with the 426 Hemi engine, making it the rarest of all options.
The lesser performing engines available for street use were beasts in their own right. Fittingly called “Super Commando” these 440ci V8 engines came with either a four- or six-barrel carburetor (three two-barrel to be precise) and made up the majority of the Superbird production run. The six-barrel carburetor produced 390 wild stallions, while the 440cid with a single, four-barrel carburetor had an output of 375hp.
The Superbird served its purpose. Plymouth’s design was so good their former star driver, Richard Petty returned for the 1970 season. Their efforts were equally validated by commanding the NASCAR circuit for the season. The Superbird became well known for its quick-paced performance dynamics and razor-sharp handling, as Petty triumphed with his eight victories. Yet, the Superbird’s success was short-lived.
Another misconception is that the Superbird and other “aero-body” cars were banned by NASCAR the following season. It’s true NASCAR officials thought these vehicles had an unfair advantage, and they were worried because their 200mph speeds were too fast for the safety technology of the time. Therefore, they changed the rules to discourage but did not outright ban these aerodynamic designs. The 1971 season limited the aero cars to an engine displacement no greater than 305ci (5.0L) or required them to increase their weight a great deal. The additional weight or the lesser horsepower would make the Superbird far less competitive. As a result of these changes, the project was scrapped.
The Superbird’s single production year makes it quite rare. NASCAR raised the homologation requirement in 1970 to one for every two manufacturer’s dealers. This meant Plymouth had to build almost four times as many cars as Dodge. Plymouth had to build and make available 1,920 Superbirds to the public.
When the 1970 Plymouth Road Runner Superbird was new, few liked them. They were considered ugly, and while some enjoyed their performance, the Superbird was far from a market success. Its appearance was too extreme, and dealers struggled selling something so radical. As they sat unsold on back lots for years, many were converted back into 1970 Road Runners to move them off the lots.
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