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, th…
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 | Refer to vehicle handbook / manufacturer specification | |
Dry weight | 184 kg |
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.
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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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The LZ9 is generally robust for daily use, but pre-2008 models show higher intake gasket failure rates under high-heat conditions. Later revisions with improved gasket design are more durable. Regular oil changes with GM 5W-30 and coolant service are essential. Well-maintained units can exceed 200,000 miles, especially in highway-driven applications.
Key issues include intake manifold gasket leaks, VVT solenoid clogging, rocker arm wear, and coolant leaks. These are documented in GM service bulletins, particularly SIB 10-06-01-005 for intake updates. Fleet vehicles in high-temperature environments report higher VVT and gasket fault rates.
The LZ9 was used in the Chevrolet Impala (2006-2011), Monte Carlo (2006-2007), and Pontiac G6 (2006-2010). It was not used in trucks or crossovers. No passenger car applications outside mid-size sedans exist.
Aftermarket ECU tuning is common on the LZ9 platform, but increasing boost or altering engine parameters accelerates component wear, impacts emissions compliance, and may void vehicle warranties. Any modifications should be evaluated carefully by a qualified specialist.
In a Chevrolet Impala, expect 20-22 mpg (US) (~11-12 L/100km) on highway, and 16-18 mpg (US) in city driving. Real-world economy depends heavily on driving style. Fleet data shows average consumption of 18 mpg (US) across mixed operations.
No. The LZ9 is a non-interference engine, meaning piston-to-valve contact will not occur if timing is lost. This reduces risk of catastrophic internal damage in the event of timing chain or gear failure, enhancing long-term reliability.
GM specifies 5W-30 synthetic gasoline engine oil. Oil must be changed every 15,000 miles or as per maintenance schedule. Using non-GM oils may void warranty and increase wear in the VVT system and valvetrain.
Comprehensive technical documentation and regulatory references
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GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
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