Power for the Avalanche is supplied by a pair of Vortec V8 engines: a 5.3L and a 6.0L. Base two-wheel drive models are powered by a 320 horsepower and 340 lb-ft of torque version of the 5.3L V8 with Active Fuel Management -- a technology that deactivates four cylinders at cruising speed to increase fuel economy. Standard on four-wheel drive models -- and optional on two-wheel models -- is an E85 FlexFuel version of the 5.3L V8, rated at 310 horsepower and 335 lb-ft of torque.A 6.0L Vortec V8 with Active Fuel Management -- rated at 366 horsepower and 380 lb-ft -- is available on four-wheel drive LT3 and LTZ models.
