Plymouth Road Runner is a mid-size performance muscle built by Plymouth between 1968 and 1980. 

The first generation Road Runner, based on the Chrysler B platform, was powered by a 335 hp 6.3-liter V8 mated to a 3-speed automatic or 4-speed manual transmission and came in 2-door coupe, hardtop, and convertible body styles. A 7.0-liter 425-hp V8 was also available as an option.

The second generation Road Runner, which debuted in 1970, featured a 300 hp 5.2-liter V8. In terms of interior comfort, the second generation came with 6-way power leather seats, thick deep-pile carpeting, and additional sound-proofing. Optional features included air conditioning and power steering. The 1972 model was virtually identical, with the exception of changes to the grille design and tail lights. The replacement of the big-block 383 with a 400 CID engine as the base power train paired with a 4-speed manual transmission was a notable feature.

We present a modified version of the 1972 Plymouth Road Runner that produces 1,100 horsepower without the use of a turbocharger. The hungry V8 is fed by dual King Demon 1080 cfm carburetors. The original torsion bar suspension with modified shocks is used on the Custom Road Runner. A 727 TorqueFlite transmission channels power to the Dana 60 rear end. Interior is intact except the front seat cover and a new set of carpets. 

Pic Courtesy: Dodge Forum