General Motors finally put real numbers behind the small blocks that power the redesigned Silverado 1500 and Sierra 1500. The 5.7- and 6.6-liter mills held back the fine print until now, including their official regular production option codes.

    

L76 is the designation of the lesser engine, which replaces the old 5.3-liter small block. This unit makes 402 horsepower and 428 pound-feet (580 Newton-meters) of twist. Upgrading to the L78 gives prospective customers 481 horsepower and 501 pound-feet (679 Newton-meters) to play with, enough to make this 6.6-liter engine the most powerful naturally aspirated V8 gasser in the half-ton segment.