1970 Plymouth Superbird.

The short-lived Plymouth Road Runner Superbird was a highly modified version of the Plymouth Road Runner, which itself was simply a modified Belvedere with special drivetrain and suspension options (along with the well known graphics and horn). It was the factory's follow on stock car racing design for the 1970 season to the Dodge Charger Daytona of 1969, and incorporated many engineering changes and modifications (both minor and major) garnered from the Daytona's season in competition on the track. The cars primary rival was the Ford Torino Talladega, which in itself was a direct response to the Mopar aero car. It has also been speculated that one of the major motivating factors in the production of the car was to lure Richard Petty back to Plymouth. Both of the Mopar aero cars famously featured a protruding, aerodynamic nosecone, a massive rear spoiler (referred to as a "wing" in the street version), and, in the case of the Superbird, the same horn which mimicked the Road Runner cartoon character.

History.

Developed specifically for NASCAR racing, the Superbird, a modified Plymouth Road Runner/Belvedere, was Plymouth's follow on design to the Charger Daytona fielded by sister company Dodge in the previous season. The Charger 500 version that began the 1969 season was the first American car to be designed aerodynamically using a wind tunnel and computer analysis, and later was modified into the Daytona version with nose and tail. The Superbird's smoothed-out body and nosecone were further refined from that of the Daytona, and in the street verion with functionally retractable headlights added nineteen inches to the Road Runner's original length. The rear spoiler, or "wing", was mounted on tall vertical struts that put it into less disturbed air thus increasing the efficiency of the downdraft that it placed upon the cars rear axle. In street versions, it was designed to provide clearance for the trunklid to open freely. The rear-facing fender scoops were incorporated in an effort to ventilate trapped air from the wheel wells in order to facilitate brake cooling.


A Mopar Orange Plymouth SuperbirdIn response, NASCAR's homologation requirement demanded that vehicles to be raced must be available to the general public and sold through dealerships in specific minimum numbers. For 1970, NASCAR raised the production requirement from 500 examples to one for every 2 Manufacturer's dealers in the United States; in the case of Plymouth, that meant having to build 1,920 Superbirds. Due to increasing emmisions regulations, combined with insurance hikes for high performance cars, 1970 would be its only production year.

"Superbird" decals were placed on the outside edges of the spoiler vertical struts featuring a picture of the Road Runner cartoon character holding a racing helmet. A smaller version of the decal appears on the driver side headlight door. The Superbirds had 3 engine options: the 426 Hemi engine, the 440 Super Commando with a single 4-barrel carburetor, or the 440 Super Commando Six Barrel with three two-barrel carburetors. Only 135 models were fitted with the 426 Hemi. As the 440 was less expensive to produce, the "Street" version of the 426 Hemi engine used in competition was homologated by producing the minimum number required.

On the street, the nosecone and wing were very distinctive, but the aerodynamic improvements hardly made a difference there or on the drag strip. In fact, the 1970 Road Runner was actually quicker in the quarter mile and standard acceleration tests due to the increased weight of the Superbird's nose and wing. Only at speeds in excess of 90 mph did the modifications show any benefit.