The Chevrolet LS6 is a 5,665 cc, V8 gasoline engine produced between 2001 and 2005. It features overhead valve (OHV) architecture with two valves per cylinder, sequential multi-port fuel injection, and an aluminum block and heads. In standard configuration, it delivers 385 hp (287 kW) and 385 lb-ft (522 Nm) of torque, providing high-revving performance and strong top-end power ideal for sports car applications.
Fitted to models such as the Chevrolet Corvette (C5 Z06) and Cadillac CTS-V (2004–2005), the LS6 was engineered for high-performance driving with enhanced breathing and valvetrain components. Emissions compliance was achieved through exhaust gas recirculation (EGR), catalytic converters, and closed-loop fuel control, allowing the engine to meet EPA Tier 2 Bin 5 and California LEV II ULEV-200 standards across its production run.
One documented concern is intake manifold bolt loosening observed in 2001–2002 production units, highlighted in General Motors Service Information Bulletin 03072. The issue arises from inadequate thread-locking compound application during assembly, leading to vacuum leaks and rough idle. GM issued a revised torque specification and thread-locking procedure in 2003 to resolve the condition.
Production years 2001–2002 meet EPA Tier 2 Bin 5; 2003–2005 models comply with updated evaporative emissions requirements (EPA-HQ-OAR-2009-0695).
The Chevrolet LS6 is a 5,665 cc V8 gasoline engine engineered for high-performance sports car platforms (2001–2005). It combines OHV pushrod design with performance-oriented valvetrain components to deliver responsive high-RPM power and track-capable reliability. Designed to meet EPA Tier 2 Bin 5 and California LEV II standards, it balances performance with emissions compliance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 5,665 cc | |
| Fuel type | Gasoline | |
| Configuration | V8, OHV, 16-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 101.6 mm × 88.4 mm | |
| Power output | 287 kW (385 PS) @ 6,000 rpm | |
| Torque | 522 Nm @ 4,800 rpm | |
| Fuel system | Sequential multi-port fuel injection | |
| Emissions standard | EPA Tier 2 Bin 5, LEV II ULEV-200 | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Double roller chain | |
| Oil type | GM 4718M 10W-30 or 5W-30 | |
| Dry weight | 188 kg |
The LS6's high-lift camshaft and lightweight valvetrain provide strong top-end pull ideal for spirited driving and track use, but require adherence to 10,000-mile oil change intervals to prevent lifter wear and timing chain degradation. GM 4718M 10W-30 or 5W-30 oil is recommended due to its shear stability and compatibility with the hydraulic lifter system. The sequential fuel injection demands TOP TIER detergent gasoline to prevent injector clogging. Post-2003 models feature revised intake manifold bolt torque and thread-locking procedures; pre-2003 units should be inspected per GM SIB 03072. Catalytic converters require monitoring to avoid thermal degradation from prolonged rich mixtures or misfires.
Oil Specs: Requires GM 4718M specification (GM SIB 03072). Supersedes earlier GM oil standards.
Emissions: EPA Tier 2 Bin 5 applies to all 2001–2005 models (EPA File EPA-2001-CHEV-002). California models meet LEV II ULEV-200 standards.
Power Ratings: Measured under SAE J1349. Output assumes 91 octane fuel (GM TIS Doc. 30780).
General Motors Technical Information System (TIS): Docs 30780, 31002, SIB 03072
EPA Certification Database (EPA-2001-CHEV-002)
SAE International: J1349 Engine Power Certification Standards
The Chevrolet LS6 was used across Chevrolet's C5 platform with longitudinal mounting and shared architecture with Cadillac variants. This engine received platform-specific adaptations-reinforced cylinder heads in the Corvette Z06 and revised intake tuning in the CTS-V-and from 2003 the facelifted Z06 models adopted the LS6 with updated intake bolt torque and ECU calibration, creating interchange limits. Partnerships allowed Cadillac's CTS-V to use the LS6 with minor calibration differences. All adaptations are documented in OEM technical bulletins.
Locate the engine ID tag on the passenger side cylinder head near the exhaust manifold (GM TIS 30780). The 8th VIN digit indicates engine type ('L' for LS6 series). Pre-2003 models have silver valve covers with black coil packs; post-2003 units use black valve covers with chrome accents. Critical differentiation from LS1: LS6 has a 10.5:1 compression ratio, larger intake ports, and revised camshaft profile. Service parts require model year verification - intake manifold bolts for 2001–2002 models are incompatible with 2003+ due to torque and thread-locking redesign (GM SIB 03072).
The LS6's primary reliability risk is intake manifold bolt loosening in early production models, with elevated incidence in high-temperature and high-vibration applications. Internal GM quality reports from 2003 indicated approximately 4% of 2001–2002 units required bolt re-torque before 90,000 miles, while NHTSA field reports confirm related rough idle and SES light entries. Frequent thermal cycling and track use accelerate bolt fatigue, making timely inspection and preventive re-torquing critical.
Analysis derived from General Motors technical bulletins (2001-2005) and NHTSA failure statistics (2002-2010). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about CHEVROLET LS6.
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