The GM LH8 is a 5,328 cc, 90‑degree V8 petrol engine produced between 2008 and 2012. It features a cast iron block, aluminum heads, and overhead valve (OHV) pushrod architecture with variable valve timing (VVT) on the exhaust cam. This Vortec engine delivered 300 hp and 320 lb‑ft of torque, emphasizing low — end grunt and towing capability for truck applications.
Fitted to models such as the Hummer H3 Alpha and Chevrolet Colorado/GMC Canyon (in certain markets), the LH8 was e…
All production years (2008–2012) meet U.S. Tier 2 Bin 5 standards (EPA Engine Family Code: 3GAXV05.3LBAK).
The GM LH8 is a 5,328 cc 90-degree V8 petrol engine engineered for mid-size trucks and SUVs (2008-2012). It combines OHV architecture with exhaust-only VVT to deliver strong low-RPM torque and rugged durability. Designed to meet U.S. Tier 2 Bin 5 standards, it prioritizes towing capacity and off-road performance.
| Parameter | Value | Source |
|---|---|---|
Displacement | 5,328 cc | |
Fuel type | Petrol (Gasoline) | |
Configuration | 90° V8, OHV, 2 valves per cylinder | |
Aspiration | Naturally aspirated | |
Bore × stroke | 99.0 mm × 86.0 mm | |
Power output | 300 hp (224 kW) | |
Torque | 320 lb-ft (434 Nm) | |
Fuel system | Sequential multi-port fuel injection (SFI) | |
Emissions standard | U.S. Tier 2 Bin 5 | |
Compression ratio | 9.9:1 | |
Cooling system | Water-cooled | |
Turbocharger | None | |
Timing system | Chain-driven camshaft with VVT actuator | |
Oil type | SAE 5W-30 API SM/SN | |
Dry weight | 485 lb (220 kg) |
The GM LH8 was used across GM's GMT355 platform with longitudinal mounting and no external licensing. This engine was a performance upgrade over the base LLR 3.7L I5, featuring unique engine mounts and accessory brackets for the Hummer H3 versus the Colorado/Canyon. From 2010, the VVT actuator was revised for improved durability, creating a key service part difference. All adaptations are documented in OEM technical bulletins.
The LH8's primary reliability risk is exhaust cam VVT actuator failure, with elevated incidence in high-mileage or poorly maintained vehicles. GM internal data indicated a significant number of warranty claims for actuator replacement, while owner reports consistently cite reduced power and check engine lights as common symptoms. Extended oil change intervals and use of incorrect oil viscosity make the updated actuator and strict maintenance critical.
Analysis derived from GM technical bulletins (2008-2012) and NHTSA complaint data (2008-2015). Repair procedures should follow manufacturer guidelines.
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The LH8 is generally a robust and durable engine with a simple OHV design. Its main weakness is the original exhaust cam VVT actuator, which is prone to failure. With the updated actuator installed and proper maintenance (especially oil changes), the LH8 can reliably exceed 200,000 miles.
The most frequent issue is the failing exhaust cam VVT actuator, causing reduced power and check engine lights. Other common problems include oil leaks from the valve covers, intake manifold gasket leaks, and spark plug/coil failures. These are well-documented in GM service bulletins.
The LH8 5.3L V8 was used in the Hummer H3 Alpha (2008-2010) and select international markets for the Chevrolet Colorado and GMC Canyon (2009-2012). It was a unique engine, not shared with GM's full-size trucks, and was specifically developed for the GMT355 platform.
The LH8 has moderate tuning potential. Basic bolt-ons like a cold air intake and cat-back exhaust can yield 10-20 hp. More significant gains require ECU tuning, which can unlock 30-40+ hp by optimizing ignition and fuel maps. Major power increases require internal modifications due to the unique block architecture.
Fuel economy is typical for a 5.3L V8 in a mid-size truck/SUV. In a Hummer H3 Alpha, expect around 13 mpg city and 16 mpg highway. Real-world combined fuel economy usually falls between 14-15 mpg, heavily influenced by driving conditions and vehicle load.
No. The GM LH8 is a non-interference engine. This means if the timing chain were to fail or jump, the pistons will not contact the valves. While a broken chain will still leave you stranded, it prevents catastrophic internal engine damage, making it a more forgiving design.
GM recommends SAE 5W-30 motor oil for the LH8 engine. The oil should meet the API SM or SN specification (or a newer equivalent). Regular oil changes every 5,000 miles are crucial for long-term engine health, particularly for the VVT system and timing chain.
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