It's Barry Kluczyk's look at a big engine that came in an unconventional (and very unassuming) package for the period: a 500-horsepower, 550 lb-ft Bill Mitchell 427-cubic-inch small block.

The Chevy big-block series of engines is legendary, but they don't all measure up the same. These are some of the most powerful big blocks ever built.

The legendary Chevy big-block 396 V-8, got bored-out in 1970 to 402 cubic inches, but was still called the 396. The '70 version produced 350 horsepower and 415 pound-feet of torque.

Under the hood, Doughboy is powered by a monstrous 540 cubic-inch twin-turbo big block engine built by ACE Racing Engines, delivering an extraordinary 2,800 horsepower.

Under the hood, it packed a 427-cubic-inch big-block engine with aluminum heads and other performance upgrades. With only 116 ever made, it’s also one of the rarest Corvettes.

Also putting in work was a 440-cubic-inch big-block V-8, the very same unit found in more traditional muscle cars like the Dodge Charger and (eventually) the Dodge Challenger.