The Hummer H3 is powered by GM inline-five engines: a base 3.5-liter I5, a larger 3.7-liter I5 as an upgrade, and, in the H3 Alpha, an optional 5.3-liter V8.
Across its 2006–2010 production run, H3 offered a 3.5L I5 as standard, with a 3.7L I5 appearing in later years, and a performance-oriented 5.3L V8 option on the Alpha trim. These engines were typically paired with a 5-speed automatic transmission and available four-wheel-drive configurations depending on the model and year.
Engine options across the H3’s life
Here are the main engine choices that GM offered for the H3, with approximate outputs and typical drivetrain setups.
3.5L inline-five (2006–2008)
Configuration: 3.5-liter DOHC inline-five. Output: about 220 horsepower and roughly 235–242 lb-ft of torque. Transmission: 5-speed automatic. Drivetrain: available in both two-wheel-drive and four-wheel-drive configurations depending on trim.
3.7L inline-five (2009–2010)
Configuration: 3.7-liter DOHC inline-five. Output: around 242 horsepower and about 242 lb-ft of torque. Transmission: 5-speed automatic. Drivetrain: offered with four-wheel drive in appropriate trims, continuing the H3’s rugged capability.
5.3L V8 (H3 Alpha, 2009–2010)
Configuration: 5.3-liter GM Vortec V8. Output: roughly 300 horsepower and about 320 lb-ft of torque. Transmission: 5-speed automatic. Drivetrain: Alpha models used a capable four-wheel-drive setup with enhanced performance and towing capability.
The engine lineup reflects GM’s use of familiar GM powertrains in the H3, with inline-fives serving as the base and mid-range options and a late-stage V8 offering aimed at enthusiasts seeking higher performance.
Summary
In brief, the Hummer H3 used three GM-sourced engines across its production run: the base 3.5L I5, the 3.7L I5 upgrade, and the 5.3L V8 in the H3 Alpha. Power outputs ranged from about 220–300 hp and 235–320 lb-ft of torque, typically paired with a 5-speed automatic transmission and available four-wheel drive across most trims. This engine lineup helped define the H3’s balance of off-road capability and on-road performance.