2015 GMC Sierra Denali 2500HD 6.6L Duramax Diesel Engine Bay

The engine bay of the 2015 GMC Sierra Denali 2500HD reveals the 6.6-liter Duramax turbodiesel V8, identifiable by the engine cover badge, with a dense array of heavy-duty ancillaries including the turbocharger intercooler piping, large-capacity coolant reservoir, and dual batteries required to start the compression-ignition powerplant. This engine produces 397 horsepower and 765 lb-ft of torque when paired with the Allison 1000 transmission.