The Ram Air IV was the little engine that took on Hemis and 454 LS6s, while establishing Pontiac as a performance brand.

and the different displacements were done purely through bore and stroke. The Pontiac 400, which was introduced in 1967, perfectly exemplifies that because this engine was just a bored out version ...

and the different displacements were done through bore and stroke. Therefore, the Pontiac 400 was made as a high-performance muscle car engine, while the Chevy 400 was primarily used on pickup trucks.