For the 2007 model year, GM’s popular midsize trucks — the Chevrolet Colorado , GMC Canyon , and Hummer H3 SUV — will get new, larger-displacement inline four- and five-cylinder engines. The new Vortec 2.9L I-4 and Vortec 3.7L I-5 deliver more horsepower and torque than the engines they replace, giving the vehicles increased performance. The Vortec 2.9L DOHC four-cylinder with variable valve timing (VVT) replaces the previous 2.8L four-cylinder and delivers 185 horsepower (138 kW) and 190 lb.-ft. of torque (258 Nm). The Vortec 3.7L DOHC five-cylinder with VVT replaces the previous 3.5L engine and is rated at 242 horsepower (180 kW) and 242 lb.-ft. of torque (328 Nm).
The 2.9L engine produces approximately 6 percent more horsepower and 3 percent more torque than the previous four-cylinder, while the 3.7L offers a substantial 22-horsepower increase and 17 lb.-ft. more torque than the previous five-cylinder engine. The 2.9L is standard in all 2007 Colorado and Canyon models except 4WD Crew Cab; the 3.7L engine is standard in 4WD Crew Cab models and available on all others. The 3.7L engine is the only engine offered on the ’07 Hummer H3 and H3X.
Increased bore diameter
Both new engines are based on GM’s modular inline engine design, which also serves as the foundation for the award-winning 4.2L I-6 in the Chevy TrailBlazer, GMC Envoy and Saab 9-7X. They feature dual overhead camshafts, variable valve timing, electronic throttle control and other features that contribute to high levels of operating efficiency and fuel economy. Balance shafts help ensure smooth operation and reduced vibration of the engines, providing a higher level of refinement.
In addition to their larger displacement – delivered through larger, 3.76-inch (95.5 mm) bores – the 2.9L and 3.7L engines feature improved airflow in and out of the combustion chambers, which helps boost power. They also share additional upgrades and changes, compared to the previous engines:
- Larger, 1.52-inch (38.7 mm) intake valves, vs. previous 1.45-inch (37 mm) intake valves
- Larger, 1.32-inch (33.5 mm) exhaust valves, vs. previous 1.18-inch (30 mm) exhaust valves
- Revised camshaft profile optimizes valve lift and duration in accordance with larger valves
- Cylinder head airflow increased to match capabilities enabled by larger valves and revised camshaft
- New, noise-reducing oiling system uses cylinder wall squirter system enabled by a hole in each connecting rod that delivers a precise oil stream onto the cylinder wall beneath the piston
- New aluminum camshaft cover helps reduce noise
- Tighter-clearance balance shaft bushings promote quieter operation
- New, 2-megabyte powertrain control module houses new diagnostic information storage
- New cartridge-type engine block heater, which fits neatly into a specially machined block orifice; for use with available engine block heater.
Additionally, the 3.7L five-cylinder engine has several features that help it meet new BIN 5 emissions requirements, including a larger, close-coupled catalytic converter and A.I.R. system.
