Specs on the 455 Pontiac Engineby Rob Wagner
General Motors produced the Pontiac 455-cubic-inch V-8 engine from 1970 through 1976. The 455 wielded massive horsepower, but a new horsepower rating system and tighter emission controls drove the 455's power lower each year until GM abandoned the engine in 1976.
The Pontiac 455 V-8 was actually a bored out 428-cubic-inch V-8 with a bore and stroke of 4 inches by 4 inches. For the 455, Pontiac expanded the cylinder bore to 4.152 inches and the stroke to 4.21 inches. The 455 powered the Pontiac GTO and Firebird.
Horsepower and Torque
The 1970 to 1971 Pontiac 455 generated 325 and 455 foot-pounds of torque. The 455 High Output generated 335 horsepower and 480 foot-pounds of torque for 1970 and 1971. However, power steadily declined beginning in 1972 when Pontiac reduced it to 300 horsepower and 415 foot-pounds of torque. In 1973, a 250-horsepower 455 with 370 foot-pounds of torque surfaced along with a 455 Super Duty, which provided 310 horsepower and 390 foot-pounds of torque. By 1976, the 455 was limping along at 200 horsepower and 330 foot-pounds of torque.
At its peak in 1971, the 335-horsepower Pontiac 455 clocked zero to 60 mph in 5.9 seconds and the quarter-mile in 13.9 seconds at 103 mph.