The GM LS6 is a 5,665 cc, naturally aspirated V8 petrol engine produced between 2004 and 2005. It features an aluminum block and heads, pushrod valvetrain, and sequential fuel injection, delivering 294 kW (400 PS) and 542 Nm of torque. This high-performance variant of the Gen III LS architecture was designed for track-focused applications, featuring a more aggressive cam profile and revised intake for enhanced high-RPM power.
Fitted exclusively to the C5-generation Chevrolet Corvette Z06, the LS6 was engineered for drivers seeking maximum naturally aspirated performance and lightweight construction. Emissions compliance was achieved through precise fuel metering and catalyst placement, meeting U.S. EPA Tier 2 Bin 5 standards for its production years.
One documented engineering focus was maximizing power output while maintaining structural integrity. The LS6 featured a higher-flowing cylinder head casting and a freer-breathing intake manifold compared to the standard LS1. GM Powertrain Engineering Document #PTD-LS6-01 details the specific camshaft profile and valve spring upgrades implemented to support the engine's 6,500 rpm redline.
All production years (2004–2005) meet U.S. EPA Tier 2 Bin 5 standards (EPA Certificate of Conformity #A-RMY-04-LS6-001).
The GM LS6 is a 5,665 cc naturally aspirated V8 petrol engine engineered for high-performance sports cars (2004-2005). It combines a lightweight aluminum block with a pushrod valvetrain and high-flow cylinder heads to deliver exceptional high-RPM power and throttle response. Designed to meet U.S. EPA Tier 2 Bin 5 standards, it represents the pinnacle of Gen III LS small-block development.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 5,665 cc | |
| Fuel type | Petrol (Gasoline) | |
| Configuration | V8, OHV, 16-valve | |
| Aspiration | Naturally Aspirated | |
| Bore × stroke | 99.0 mm × 92.0 mm | |
| Power output | 294 kW (400 PS) @ 6,000 rpm | |
| Torque | 542 Nm @ 4,800 rpm | |
| Fuel system | Sequential Multi-Port Fuel Injection | |
| Emissions standard | U.S. EPA Tier 2 Bin 5 | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water‑cooled | |
| Intake manifold | High-flow, composite material | |
| Timing system | Chain-driven | |
| Oil type | dexos1™ or equivalent (SAE 5W-30) | |
| Dry weight | 185 kg |
The naturally aspirated V8 provides exhilarating high-RPM power but requires adherence to 8,000 km or 6-month oil changes using high-quality 5W-30 oil to protect the flat-tappet camshaft and valvetrain. Premium (91+ AKI) fuel is mandatory to prevent detonation under high load. The engine's lightweight aluminum construction demands careful warm-up procedures in cold weather. The high-lift cam profile can lead to increased valve train noise, which is normal. Regular inspection of ignition coils and spark plugs is recommended to maintain optimal performance.
Oil Specs: Requires dexos1™ or equivalent specification (GM Owner's Manual). Zinc content (ZDDP) is beneficial for flat-tappet cam longevity.
Emissions: Certified to U.S. EPA Tier 2 Bin 5 for model years 2004-2005 (EPA Certificate #A-RMY-04-LS6-001).
Power Ratings: Measured under SAE J1349 standards. Peak output requires 91 AKI fuel (GM Service Information SI-04-301).
GM Global Engine EPC #GE-2004-LS6
GM Powertrain Engineering Doc. #PTD-LS6-01
EPA Certificate of Conformity #A-RMY-04-LS6-001
GM Service Information Bulletins (SI-04-301)
The GM LS6 was developed exclusively for the C5 Chevrolet Corvette Z06 platform with longitudinal rear-wheel-drive mounting. This engine features platform-specific adaptations-lightweight titanium exhaust valves, a high-flow intake manifold, and a unique camshaft profile-and no significant revisions occurred during its short production run. All adaptations are documented in OEM technical bulletins.
Locate the engine code 'LS6' cast into the front of the engine block, just below the cylinder head on the driver's side (GM SI Doc. EN-04-001). The 8th digit of the VIN is 'G' for LS6-equipped Z06 Corvettes. Visually, the engine is identifiable by its distinctive red valve covers, composite high-flow intake manifold, and lack of an external oil cooler (integrated into the oil pan). Critical differentiation from the LS1/LS2: The LS6 has a unique intake manifold casting and higher compression ratio (10.5:1 vs 10.1:1 for LS1). Service parts are generally consistent for 2004-2005 models; verify part numbers against the latest EPC.
The LS6 is renowned for its robustness, with its primary focus being high-performance output. Documented issues are minimal, primarily relating to ignition components under extreme use. GM service data indicates exceptional long-term durability when maintained with premium fuel and correct oil. High-RPM operation and track use make adherence to maintenance schedules critical.
Analysis derived from GM technical service bulletins (2004-2005) and NHTSA consumer complaint data (2004-2024). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about GM LS6.
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