LQ9 Engine

Specifications

The GM LQ9 engine is a 6.0-liter (364 cubic inch) Vortec V8 belonging to General Motors’ Gen III LS-based engine family, designed primarily for performance-oriented trucks and SUVs such as the Cadillac Escalade, Silverado SS, and GMC Sierra Denali between 2002 and 2007. It uses a cast-iron engine block for strength and durability, paired with aluminum cylinder heads featuring a cathedral-port intake design and 2.00-inch intake 1.55-inch exhaust valves. The engine follows a pushrod (OHV) configuration with 16 valves, hydraulic roller lifters, and a 9.4:1 compression ratio, which allows higher output but requires premium gasoline.

The LQ9 uses electronic fuel injection, coil-near-plug ignition, and a 24x crank reluctor wheel, making it compatible with many early LS engine management systems. Unlike later aluminum-block LS engines, the iron construction adds weight but significantly improves strength, making the LQ9 well-suited for boosted applications, heavy towing, and high-horsepower builds. It was commonly paired with the 4L65E automatic transmission and features a return less fuel system. The LQ9 is highly regarded in the performance and swap community due to its reliability and excellent aftermarket support. 

Compatible Models

Cadillac Escalade / Escalade EXT / Escalade ESV (2003–2007)

From 2003 to 2007, the Cadillac Escalade lineup including the standard Escalade, EXT pickup, and extended-length ESV was powered by the 6.0-liter LQ9 V8, delivering approximately 345 horsepower and 380 lb-ft of torque. These models combined a high-output LS-based engine with a 4L65E automatic transmission, offering strong acceleration for a luxury SUV while maintaining excellent towing capability. The LQ9’s iron block and higher compression tuning required premium fuel, and in AWD configurations it was paired with a full-time all-wheel-drive system for confident all-weather performance. These Escalades were known for blending luxury, durability, and V8 power, making them some of the most capable premium SUVs of their era.  

Chevrolet Silverado SS (2003–2007)

The Chevrolet Silverado SS was GM’s factory performance pickup, featuring the LQ9 6.0-liter Vortec V8 rated at about 345 hp and 380 lb-ft of torque. Available in rear-wheel drive and later all-wheel drive configurations, the Silverado SS used a sport-tuned suspension, unique exterior styling, and a 4L65E automatic transmission to translate its high-output engine into strong street performance. Shorter axle gearing and performance calibration improved acceleration, while the robust iron-block LQ9 retained the torque and reliability expected from a full-size truck. The Silverado SS became an icon by combining muscle-truck performance with everyday usability. 

Chevrolet Silverado / GMC Sierra VortecMAX (2006–2007)

The VortecMAX Edition Silverado and Sierra models (2006–2007) represented the ultimate performance-towing package in GM’s light-duty trucks, centered around the LQ9 6.0-liter high-output V8 producing roughly 345 horsepower and 380 lb-ft of torque. These trucks featured heavy-duty cooling, a 4.10 rear axle ratio, reinforced drivetrain components, and a 4L65E automatic transmission, giving them towing capabilities approaching heavy-duty models while retaining 1500-series ride quality. Suspension and braking upgrades complemented the drivetrain, making VortecMAX trucks highly capable for towing, hauling, and performance driving, and especially popular among enthusiasts seeking factory-installed LS power with maximum durability.  

Frequently Asked Questions