Chevrolet Colorado Duramax Diesel is balanced for smoothness
Colorado's new 2.8L Duramax turbo-diesel is part of GM's family of turbo-diesel four-cylinder engines. It features a variable-geometry turbocharger for optimal power and efficiency across the rpm band and a balance shaft for greater smoothness. Power is SAE-certified at 181 horsepower (135 kW) at 3,400 rpm and 369 lb-ft of torque (500 Nm) at 2,000 rpm. A broad torque band makes it very powerful at low rpm, while the turbocharged performance provides a feeling of immediate and smooth horsepower.
The Duramax 2.8L is the cleanest diesel truck engine ever produced by General Motors, and meets some of the toughest U.S. emissions standards, thanks in part to a cooled exhaust gas recirculation (EGR) system.
The cooled EGR contributes to lower emissions by diverting some of the engine-out exhaust gas and mixing it back into the fresh intake air stream, which is drawn into the cylinder head for combustion. That lowers combustion temperatures and rates, improving emissions performance by reducing the formation of NOx. To control vibration and noise, engineers integrated the Centrifugal Pendulum Vibration Absorber (CPVA) in the torque converter used with the standard Hydra-Matic 6L50 six-speed automatic transmission.
It marks the first application of a CPVA in a GM vehicle and the first time it has been used in the midsize truck segment.
The CPVA is an absorbing damper with a set of secondary spring masses, that — when energized — cancels out the engine's torsional vibrations so the driver and passengers can't feel them. In its unique design, the spring masses vibrate in the opposite direction of the torsional vibrations of the engine, balancing out undesirable torsional vibrations. The Colorado's driver-selectable exhaust brake system and uses the compression power of the 2.8L Duramax engine to improve vehicle control and reduce brake pad wear.
When the exhaust brake is engaged in cruise mode, exhaust cruise grade braking will help the cruise control system maintain the desired vehicle speed when travelling downhill, keeping the driver from having to apply the brakes and exit cruise control to maintain speed. When the exhaust brake is engaged in non-cruise mode, the transmission and the exhaust brake deliver the correct amount of braking to assist in vehicle control, regardless of vehicle load. It is a smart system that varies the amount of brakes needed for the vehicle, load and grade. ■