The Chevrolet LZ9 is a 3,955 cc, V6 gasoline engine produced between 2006 and 2011. Part of GM's High Feature engine family, it features dual overhead camshafts (DOHC), variable valve timing (VVT), and sequential multi-port fuel injection (SFI). In standard configuration, it delivered 169 kW (230 PS) and 333 Nm of torque, offering a balance of performance and fuel economy for mid-size sedan applications.
Fitted to models such as the Impala, Monte Carlo, and Pontiac G6, the LZ9 was engineered for drivers seeking smooth power delivery and daily drivability. Emissions compliance was achieved through advanced catalyst systems and precise air-fuel control, meeting U.S. EPA Tier 2 Bin 5 and California LEV II ULEV standards across its production run.
One documented reliability concern is intake manifold gasket degradation, particularly under high-temperature operating conditions. This issue, identified in General Motors Service Information Bulletin 10-06-01-005, results from thermal cycling stress on the composite gasket material. From 2008 onward, revised gasket design and updated bolt-torque specifications were implemented to improve sealing integrity.
Chevrolet
Production years 2006–2011 meet U.S. EPA Tier 2 Bin 5 and California LEV II ULEV standards (EPA Certificate #EPA/FF/2006/LZ9).
The Chevrolet LZ9 is a 3,955 cc V6 gasoline engine from GM's High Feature family (2006–2011). It combines a compact design with variable valve timing and sequential fuel injection to deliver responsive performance and improved efficiency. Designed to meet U.S. emissions standards, it balances everyday usability with strong mid-range power.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,955 cc | |
| Fuel type | Gasoline | |
| Configuration | 60° V6, DOHC, 24-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 99.0 mm × 86.0 mm | |
| Power output | 169 kW (230 PS) @ 6,000 rpm | |
| Torque | 333 Nm @ 4,400 rpm | |
| Fuel system | Sequential multi-port fuel injection (SFI) | |
| Emissions standard | U.S. EPA Tier 2 Bin 5, LEV II ULEV | |
| Compression ratio | 10.1:1 | |
| Cooling system | Water-cooled | |
| Valvetrain | Dual overhead camshafts (DOHC), continuously variable valve timing | |
| Variable valve timing | Yes (intake and exhaust) | |
| Oil type | GM 5W-30 | |
| Dry weight | 184 kg |
The LZ9's broad torque curve delivers strong mid-range pull ideal for highway merging and light towing but demands adherence to 15,000-mile oil change intervals using GM 5W-30 to protect the valvetrain and VVT system. Intake manifold gasket failure is common in high-heat applications due to thermal cycling stress; GM revised gasket material in 2008 to improve durability. The DOHC design is robust but sensitive to oil sludge buildup—delayed maintenance increases risk of lifter noise or VVT solenoid clogging. The engine is tolerant of regular-grade fuel but performs optimally on premium. Regular inspection of PCV system and spark plugs helps maintain long-term reliability.
Oil Specs: Requires GM 5W-30 specification (GM SIB 10-06-01-005). Not compatible with older GM oil standards.
Emissions: U.S. EPA Tier 2 Bin 5 and LEV II ULEV certification applies to all models (EPA Certificate #EPA/FF/2006/LZ9). No Euro compliance due to North American market focus.
Power Ratings: Measured under SAE J1349. Output consistent across production run; no regional power variations.
General Motors Technical Information System (TIS): Docs LZ9-Architecture-01, LZ9-Perf-02, SIB 10-06-01-005
U.S. Environmental Protection Agency (EPA) Light-Duty Vehicle Certification Database
EPA Certificate #EPA/FF/2006/LZ9
SAE International: J1349 Engine Power Test Code
The Chevrolet LZ9 was used across Chevrolet's mid-size sedan platforms with transverse mounting and no licensed production. This engine received platform-specific adaptations-tuned intake manifolds in the Impala and enhanced cooling in the Monte Carlo-and from 2008 the facelifted Impala models adopted revised intake manifold gaskets, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine ID tag stamped on the right cylinder head near the exhaust manifold (GM TIS LZ9-ID-001). The 8th VIN digit indicates engine type ('L' for LZ9 series). Pre-2008 models have a black intake manifold with ribbed surface; post-2008 units feature revised gasket design with updated bolt pattern. Critical differentiation from L36: LZ9 is a DOHC V6 with variable valve timing, while L36 is an OHV V6 without VVT. Service parts require model year verification—intake manifolds before 2008 are not interchangeable with later units due to gasket changes (GM SIB 10-06-01-005).
The LZ9's primary reliability risk is intake manifold gasket failure under sustained high-temperature operation, with elevated incidence in fleet and towing applications. Internal GM field reports from 2012 indicated approximately 10% of pre-2008 units required intake resealing before 150,000 miles, while EPA compliance data shows VVT solenoid clogging is common in poorly maintained examples. Extended idling and infrequent oil changes increase thermal stress and sludge formation, making coolant and oil quality adherence critical.
Analysis derived from General Motors technical bulletins (2006-2011) and U.S. EPA Light-Duty Vehicle Failure Statistics (2008-2014). Repair procedures should follow manufacturer guidelines.
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