Hummer H3 Alpha

The H3 Alpha's 5.3L engine is a powerful and efficient member of  GM's legendary small-block V-8 family. It is rated at 295 horsepower (224 kW) and 317 lb.-ft. of torque (438 Nm); and is similar to the small-block V-8 found in the Chevy Silverado, which was named the 2007 Truck of the Year at the North American International Auto Show. "For jobs such as towing personal watercraft up a mountain to the lake, the small-block V-8's torque performs with effortless ease and little impact on fuel mileage," said Christopher Meagher, assistant chief engineer of small-block V-8 truck engines. "The 5.3L engine greatly broadens the H3's towing capability."Effortless highway driving also is an attribute of the 5.3L V-8, which enables 0-60 mph performance of approximately eight seconds.

"All of the powertrain options in the H3 lineup deliver performance suited to different driving styles and needs," said Meagher. "But when it comes to certain tasks such as towing, there is sometimes no substitute for a V-8 engine."

An aluminum cylinder block is used with the H3 Alpha's engine. It helps reduce overall mass and maintains a more desirable front-to-rear weight balance. Like all of GM's small-block V-8 engines, highlights include:

• Deep-skirt cylinder block with cross-bolted main caps


• High-flow cylinder heads


• Electronic throttle control


• 58X ignition system


• E67 32-bit controller


• Polymer-coated pistons with full-floating wrist pins


• Returnless fuel system


• Lightweight valvetrain


• Steel camshaft


• Low-restriction air intake system

GM's small-block V-8 engines are engineered to meet today's more stringent emissions standards. In fact, the H3 Alpha's V-8 engine beats the deadline for new, U.S. federal emissions standards by a year. And compared to truck engines of a decade ago, the small-block engine family is approximately 90 percent cleaner. Cast iron exhaust manifolds matched with four close-coupled catalytic converters help reduce cold-start emissions, which is the largest source of vehicle emissions.

A Hydra-Matic 4L60 electronically controlled four-speed automatic transmission is paired with the H3 Alpha's V-8 engine. And, as with all H3 models, flat-towing is enabled.