8. Oldsmobile 455 V8
Oldsmobile presented its own 455 V8 in 1968, basing it on the Oldsmobile big block like 425. The 455 was an updated version with more bore and stroke and different heads. In comparison to similar engines, the Olds Rocket 455 produced the highest amount of horsepower.
The base Rocket 455 V8 only produced 275 HP, but most of the engines produced 375 HP since they came with four-barrel carburetors. From 1968 to 1970, Oldsmobile produced a performance version of the Rocket 455 for the Toronado GT coupe. It produced 400 HP, which was the biggest officially-rated number. As with other big blocks from GM, they retired the Rocket 455 V8 in 1976. However, Oldsmobile produced a few more units until 1978 for motor homes and various other industrial buyers.