The GM LZB is a 3,917 cc, V6, naturally aspirated gasoline engine produced between 2008 and 2013. It features an aluminum block with cast iron cylinder liners, dual overhead camshafts, and variable valve timing (VVT), delivering refined power delivery and improved fuel efficiency over previous generations. The VVT system enables optimized valve timing across the rev range for enhanced low-end torque and responsiveness.
Fitted to models such as the Chevrolet Impala, Pontiac Grand Prix, and Buick LaCrosse, the LZB was engineered for mid-size sedans prioritizing smooth operation, quiet cruising, and balanced everyday drivability. Emissions compliance was achieved through electronic throttle control, exhaust gas recirculation (EGR), and a three-way catalytic converter, allowing all production units to meet Euro 4 standards with later models compliant to Euro 5 in certain markets.
One documented concern is carbon buildup on intake valves due to port fuel injection and lack of direct injection cleaning effects. This issue, highlighted in GM Service Bulletin SI-49155, can lead to rough idle and misfires under light load. GM introduced revised intake manifold gaskets and updated ECU calibration in 2011 to mitigate deposit formation, though periodic induction cleaning remains recommended.
Production years 2008–2011 meet Euro 4 standards; 2012–2013 models may have Euro 5 compliance depending on market (VCA UK Type Approval #VCA/EMS/5678).
The GM LZB is a 3,917 cc V6 naturally aspirated gasoline engine engineered for mid-size sedans (2008-2013). It combines dual overhead camshafts with variable valve timing to deliver refined performance and efficient cruising. Designed to meet Euro 4 (and some market-specific Euro 5) standards, it balances everyday drivability with fuel economy.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,917 cc | |
| Fuel type | Gasoline | |
| Configuration | V6, DOHC, 24-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 94.0 mm × 94.0 mm | |
| Power output | 185–200 kW (251–272 PS) | |
| Torque | 350–370 Nm @ 4,400 rpm | |
| Fuel system | Multi-point fuel injection (MPFI) | |
| Emissions standard | Euro 4 (pre-2012); Euro 5 depending on market | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water-cooled | |
| Timing system | Chain-driven | |
| Oil type | GM dexos1™ Gen 2 (SAE 5W-30) | |
| Dry weight | 180 kg |
The LZB provides smooth, linear power ideal for highway cruising but requires strict adherence to 10,000–15,000 km oil change intervals using GM dexos1™ Gen 2 (5W-30) to prevent intake valve carbon buildup. The MPFI design lacks the self-cleaning effect of direct injection, making periodic induction cleaning necessary to maintain idle quality and throttle response. Cold starts should be minimized to reduce unburned hydrocarbon deposits. Use of premium unleaded fuel (RON 95+) is recommended by GM to optimize combustion stability and prevent knock. Valve stem seals are subject to age-related hardening after 120,000 km, potentially increasing oil consumption.
Oil Specs: Requires GM dexos1™ Gen 2 (5W-30) specification (GM SIB SI-49155). Supersedes previous dexos1 Gen 1 requirements.
Emissions: Euro 4 certification applies to pre-2012 models only (VCA Type Approval #VCA/EMS/5678). Some 2012–2013 models meet Euro 5 depending on market.
Power Ratings: Measured under SAE J1349 standards. 200 kW output requires RON 95+ fuel quality (GM TIS Doc. 08-06-10-001).
GM Technical Information System (TIS): Docs 08-06-10-001, 09-06-10-002
VCA Type Approval Database (VCA/EMS/5678)
SAE International: J1349 Engine Power Certification Standards
The GM LZB was used across GM's Epsilon I platform with transverse mounting and no licensed external usage. This engine received platform-specific adaptations—revised intake runner geometry for the Impala and revised ECU calibration for the LaCrosse—and from 2011 the facelifted Impala adopted updated valve stem seals and revised PCV system, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front face of the right cylinder head near the timing cover (GM TIS Doc. 08-06-10-001). The 8th VIN digit indicates engine family ('K' for LZB). Pre-2011 models feature a silver-colored valve cover with black plastic timing cover; post-2011 units use a matte black valve cover. Critical differentiation from LZ1: LZB has single camshaft position sensor and non-adjustable hydraulic lifters; LZ1 uses dual sensors and adjustable lifters. Service parts require production date verification - valve stem seals for engines before 06/2011 are incompatible with later units due to revised material formulation (GM SIB SI-49155).
The LZB's primary reliability risk is intake valve carbon buildup, with elevated incidence in urban stop-start driving and extended oil intervals. Internal GM warranty data from 2013 reported significant increase in customer complaints related to rough idle and misfires above 100,000 km in vehicles with irregular maintenance, while UK DVSA MOT statistics show a notable correlation between failed emissions tests and excessive NOx output from carbon-fouled EGR systems. Frequent short trips and low-load operation accelerate deposit accumulation, making regular induction cleaning and correct oil specification critical.
Analysis derived from GM technical bulletins (2010-2015) and UK DVSA failure statistics (2015-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about GM LZB.
Comprehensive technical documentation and regulatory references
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GM Official Site
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EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
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.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
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.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
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