9. Buick 455 V8
Buick offered their 455 V8 in 1970. It came with the same displacement as the Pontiac V8, but with different technology and construction. The different bore and stroke dimensions, as well as the thin-wall casting, made the Buick unit the lightest of all GM big blocks.
The initial power output was a healthy 350 to 360 HP, but the torque was an astonishing 510 lb-ft. That was only 10 more than the Pontiac 455. That meant the Buick 455 officially became the engine with the biggest torque rating in the muscle car class. They installed this unit in the Buick luxury car lineup. Also, a small amount went to the GS, Rivieras, and GSX muscle cars. The engine was discontinued in 1976 when it produced around 250 HP.