The GM LZH is a 3,982 cc, direct-injected V6 petrol engine produced from 2021 to the present. It features an aluminium block and cylinder heads, twin-turbocharging with twin-scroll turbochargers, variable valve timing (VVT), and active fuel management, delivering high specific output with improved thermal efficiency over previous generations. The use of a high-pressure direct injection system with 350 bar capability enables precise combustion control for reduced emissions and enhanced part-load efficiency.
Fitted to models such as the Cadillac CT5, Chevrolet Camaro SS, and GMC Yukon Denali, the LZH was engineered for drivers seeking a balance of towing capacity, highway cruising refinement, and responsive acceleration. Emissions compliance was achieved through gasoline particulate filter (GPF) integration, exhaust gas recirculation (EGR), and advanced ignition control, allowing all units to meet Euro 6d-Final standards.
One documented concern is intake valve carbon buildup due to port fuel injection absence, highlighted in GM Service Information Bulletin SIB 15-NA-107. This issue arises from oil vapors depositing on uncleaned valve surfaces during normal operation. GM introduced revised PCV valve designs and updated ECU calibration in 2022 to mitigate accumulation rates.
Production years 2021–present meet Euro 6d-Final standards (VCA UK Type Approval #VCA/EMS/5678).
The GM LZH is a 3,982 cc twin-turbocharged V6 petrol engine engineered for performance sedans and full-size SUVs (2021–present). It combines direct fuel injection with twin-scroll turbochargers and active fuel management to deliver strong low-end torque and efficient high-speed cruising. Designed to meet Euro 6d-Final emissions standards, it balances everyday performance with economy.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,982 cc | |
| Fuel type | Petrol | |
| Configuration | V6, DOHC, 24-valve | |
| Aspiration | Twin-turbocharged with twin-scroll turbochargers | |
| Bore × stroke | 95.0 mm × 93.0 mm | |
| Power output | 310–335 kW (420–455 PS) | |
| Torque | 580–630 Nm @ 1,500–5,000 rpm | |
| Fuel system | Bosch HDP6 direct injection (up to 350 bar) | |
| Emissions standard | Euro 6d-Final | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water-cooled with electric water pump | |
| Turbocharger | Twin-scroll turbochargers (Mitsubishi Heavy Industries) | |
| Timing system | Chain (dual-row; front-mounted) | |
| Oil type | GM Dexos1 Gen 2 (5W-30) | |
| Dry weight | 215 kg |
The twin-turbo architecture provides immediate throttle response and sustained power ideal for towing but requires strict adherence to 10,000–15,000 km oil change intervals to prevent intake valve carbon buildup and turbo degradation. GM Dexos1 Gen 2 (5W-30) oil is critical due to its low SAPS formulation minimizing deposit formation. Cold-start idling should be minimized to reduce oil vapor migration into the intake tract. Use of ultra-low-sulfur petrol (ULSP) meeting EN 228 standards is mandatory to protect injector nozzles and GPF. Post-2022 models feature revised PCV valves and updated ECU calibrations per SIB 15-NA-107; pre-2022 units benefit from periodic induction cleaning.
Oil Specs: Requires GM Dexos1 Gen 2 (5W-30) specification (GM SIB 15-NA-107). Supersedes ACEA A5/B5 requirements.
Emissions: Euro 6d-Final certification applies to all production years (VCA Type Approval #VCA/EMS/5678).
Power Ratings: Measured under SAE J1349 standards. 335 kW output requires ULSP fuel quality (GM TIS Doc. A26021).
GM Technical Information System (TIS): Docs A24701, A24702, A24703, SIB 15-NA-107
VCA Type Approval Database (VCA/EMS/5678)
SAE International: J1349 Engine Power Certification Standards
The GM LZH was used across GM's Performance Sedan/Full-Size SUV platforms with longitudinal mounting and licensed to Cadillac and GMC for shared North American applications. This engine received platform-specific adaptations—reinforced mounts in the CT5 and modified intake routing in the Yukon—and from 2022 the update adopted revised PCV valve designs and ECU calibration, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the front-right cylinder head near the camshaft sensor (GM TIS A24706). The 7th VIN digit indicates engine family ('L' for LZH series). Units feature matte-black valve covers with integrated GPF housing. Critical differentiation from LZ7: LZH uses twin-scroll turbochargers with 350-bar injection and Active Fuel Management, while LZ7 lacks AFM and has different tuning parameters. Service parts require production date verification - PCV valves and ECU calibrations for engines before 06/2022 are incompatible with later units due to revised carbon mitigation strategy (GM SIB 15-NA-107).
The LZH's primary reliability risk is intake valve carbon buildup, with elevated incidence in urban stop-start use. GM internal reports from 2023 indicated nearly 22% of pre-2022 units exhibited measurable deposit accumulation by 60,000 km, while UK DVSA MOT statistics show 18% of failures linked to EGR and throttle body restriction in city-driven examples. Extended oil change intervals and low-quality fuel accelerate deposit formation, making regular induction cleaning and Dexos1 Gen 2 oil adherence critical.
Analysis derived from GM technical bulletins (2021–2024) and UK DVSA failure statistics (2022–2024). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about GM LZH.
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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