Newest model in the performance-bred Alpha series
Powerful 5.3L V-8 powertrain offers 295 hp (224 kW)
Maximum towing increased to 6,000 pounds (2,721 kg) – a 33-percent increase
Unique exterior and interior features, including Alpha badging
"H3 Alpha is, simply, the ultimate HUMMER H3," said Martin Walsh, HUMMER general manager. "It delivers all of H3's renowned off-road capability, but with enhanced performance that is suited to a variety of lifestyles."

The H3 Alpha is the second member of HUMMER's exclusive Alpha series, representing the pinnacle of performance, both off the road and on it. It comes with a new, 5.3L V-8 engine that delivers 295 horsepower (224 kW)* and 317 lb.-ft. of torque (438 Nm)*. It is partnered with a four-speed automatic transmission and enables a maximum towing capacity of 6,000 pounds (2,721 kg) – an increase of more than 33 percent over other H3 models

HUMMER Alpha models represent the top in performance, capability and comfort. The H1 Alpha was the first of these ultimate HUMMERs, and like the H3 Alpha, it offered a more powerful engine as well as unique styling and comfort features.
 
The new for the H3 Alpha and the entire 2008 H3 lineup are standard head curtain side air bags; they were previously optional. Additional standard safety features now found on all H3 models include:
StabiliTrak electronic stability control system
Four-wheel antilock brakes with traction control
Dual front air bags with Passenger Sensing System
Tire pressure monitoring system
Vehicle-to-vehicle crash compatibility
LATCH rear child seat anchors

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."

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 
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.

HUMMER H3 and GM Performance Division engineers did more than simply shoehorn a V-8 engine into the H3's engine compartment. Accommodating the new power plant necessitated the execution of a seemingly endless number of technical details – many of which have been implemented across the entire H3 lineup.
The H3's frame was modified to accept the V-8 engine, and a special oil pan was designed to ensure constant oil pressure when driving on steep grades – a hallmark of HUMMER's off-road capability. Also, the engine compartment front of dash was modified to accommodate the V-8, and a new steering system is used on all H3 models to deliver better on-center feel and even more improved off-road reliability.

To support the torque output of the powerful V-8, the H3 Alpha's front differential case is made of cast iron; other models feature an aluminum case. New engine mounts, higher torsion bar rates to support the increased mass, and specific shock valving also are unique to the V-8-powered model, ensuring it continues to deliver the unparalleled ride quality – both on- and off-road – that customers expect.

All of the chassis and suspension changes were validated in real-world testing on off-road trails in Moab, Utah, the Rubicon Trail and other challenging off-road venues.