|The new GM V-6 diesel. Click to enlarge.|
General Motors has unveiled a new 2.9-liter V-6 turbodiesel engine with advanced injection and combustion technology for low emissions and high performance.
The new 184 kW (250 hp) engine will be sold mainly in Europe and makes its public debut this week at the Geneva Motor Show (8-18 March). Its first production application is scheduled for 2009 in the new Cadillac CTS.
The compact dual overhead cam, four-valve V-6 engine belongs to a new GM family of diesel engines, featuring an innovative closed-loop combustion control system designed to meet future emissions standards. The engine can be installed in a longitudinal or transverse layout and can be adapted to a wide range of two- or four-wheel-drive vehicles.
GM worked with Ricardo on developing an advanced diesel engine control (ADEC) system designed to enable consistent achievement of very low emissions levels through closed loop control of the combustion process. The ADEC coordinator uses a range of sensors to measure combustion states and then establishes the optimal balance of fuel quantity and timing and air path control. (Earlier post.)
GM’s development of the new engine is being coordinated under the leadership of GM Powertrain’s European operations in Turin, Italy, in cooperation with VM Motori based in Cento, Italy. GM Powertrain will focus on the development of the clean combustion process, electronic engine control and exhaust-gas aftertreatment, as well as calibration and integration into GM vehicles. VM Motori will build the new unit at its plant in Cento, Italy, and is responsible for the mechanical aspects of the engine’s design, development and bench testing.
The V-6 engine management system enables optimal fuel economy as well as reduced emissions and noise by using a recently developed combustion control technology. Key enablers of the system are high-speed, piezo-resistive cylinder pressure sensors that are integrated within the engine glow plugs. These specialized sensors acquire real-time data from the combustion process, enabling instantaneous fine-tuning of the fuel injection process. In the future, this clean combustion control technology will be introduced in other GM Powertrain diesel engines.
A future version of such a closed loop combustion control (CLCC) system with cylinder pressure sensors will likely be an enabler of HCCI combustion regimes.
The high-pressure, common-rail system provides up to 2,000 bar (29,000 psi) injection pressure. The injectors are quick-firing, piezo-electrically actuated, allowing up to eight injections per engine cycle. The aftertreatment system includes an oxidation catalyst and a particulate filter that are close-coupled to the engine to achieve future emissions standards.
An electronically controlled variable geometry turbocharger generates boost pressure. The engine has a torque of 550 Nm (406 lb-ft) beginning at 2,000 rpm, while providing effective fuel economy and reduced emissions.
The new, compact V-6 powerhouse features aluminum cylinder heads and a 60-degree bank angle, 83.0 mm bore and 90.4 mm stroke, which results in displacement of 2,935 cubic centimeters. The engine block is made of stronger and lighter Compacted Graphite Iron (compared to lower-strength aluminum or heavier grey cast iron) to optimize engine packaging, weight, refinement and performance.
Bringing the Low NOx Diesel Under Control (GM, DEER 2006)
Glow Plug Integrated Piezo-Ceramic Combustion Sensor for Diesel Engines (Siemens VDO-Federal Mogul, DEER 2005)