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 Chevrolet Trail Blazer, 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 power train 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.
This is all the change they made. Crankshaft does not seem to be different. Can anyone confirm?
Wednesday, February 1st, 2017 AT 8:43 AM
