The 455 Pontiac V8 was introduced in 1970 and provided large-bodied Pontiacs a torque-friendly engine. Prominently featured in the Pontiac Bonneville, the 455 was also used in the GTO, Trans Am, and the Firebird.
The 455 was an improvement on the Pontiac 428 V8. High Output and Super Duty versions of the 455 were added in succeeding years. The Pontiac Grand Ville series also featured the 455 beginning in 1972.
Although the 455 has great torque, the 455’s horsepower was often adjusted due to various emissions changes, advertising gimmicks, or to appease insurance companies. The 455 High Output engine had improved cylinder heads as well as better intake and exhaust ports while the Super Duty, made in 1973, was able to produce 290 horsepower in spite of more strict emissions standards. The 455 was discontinued after 1976.
1970 - 1971 with 4 Barrel CarbMax Brake Horsepower = 325 @ 4400 rpmMax Torque = 455 @ 3200 rpmStroke = 4.21Bore = 4.15Compression = 8.2Firing Order = 18436572 1971 High Output (H.O.)Max Brake Horsepower = 335 @ 4800 rpmMax Torque = 480 @ 3600 rpmStroke = 4.21Bore = 4.15Compression = 8.2Firing Order = 18436572 1972 with 4 Barrel CarbMax Brake Horsepower = 300 @ 4000 rpmMax Torque = 415 @ 3200 rpmStroke = 4.21Bore = 4.15Compression = 8.2Firing Order = 18436572 1973 - 1974 with 4 Barrel CarbMax Brake Horsepower = 250 @ 4000 rpmMax Torque = 370 @ 2800 rpmStroke = 4.21Bore = 4.15Compression = 8.2Firing Order = 18436572 1973 - 1974 Super DutyMax Brake Horsepower = 290 @ 3600 rpmMax Torque = 380 @ 3600 rpmStroke = 4.21Bore = 4.15Compression = 8.2Firing Order = 18436572 1975 with 4 Barrel CarbMax Brake Horsepower = 200 @ 3800 rpmMax Torque = 330 @ 2000 rpmStroke = 4.21Bore = 4.15Compression = 8.2Firing Order = 18436572 1976 with 4 Barrel Carb (H.O.)Max Brake Horsepower = 200 @ 3800 rpmMax Torque = 330 @ 2000 rpmStroke = 4.21Bore = 4.15Compression = 8.2Firing Order = 18436572 