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News of  August 22, 2001


GM'S Innovative Northstar XV12 Concept Engine Showcases Future Technologies In A Compact, Fuel Efficient Package

Photo: GM

PEBBLE BEACH, Calif. - General Motors' innovative V12 concept engine, called Northstar XV12, showcases several advanced technologies in a fuel efficient, V8-like package.

This all-new high-technology, high-output 12-cylinder powerplant, featured in the 2002 Cadillac Cien mid-engine concept car, is a 60-degree, all-aluminum dual overhead cam (DOHC) four-valve engine. It displaces 7.5 liters and produces 750 horsepower (560 kW) and 450 lb-ft of torque (610 Nm), yet is packaged in the size of a V8, and able to deliver excellent fuel economy. The engine has integrated advanced technologies for the future developed by GM Powertrain's Advanced Engineering, and assembled in a compact package that GM engineers refer to as "small on the outside, big on the inside."

The Northstar XV12 represents a unique combination of a nod to the past and a glimpse of the future.

GM historically has had a vision to provide unmatched power, refinement, exclusivity and technical excellence in its powertrains. When GM's Cadillac division was solidifying its standing as the "Standard of the World" in the 1920s and 1930s, it did so powered by notable V12 and V16 engines.

The Northstar XV12 is the same length as GM's Vortec 8100 V8, and it has the approximate width and height as the Northstar 4.6-liter and Vortec 6000 V8s.

GM's Displacement on Demand enables the V12 engine to run seamlessly on six cylinders at times to maximize fuel savings, and is only one of several technological advancements showcased on the Northstar XV12. Some of the high-tech features included in Northstar XV12's capabilities:

Displacement on Demand

The cylinder shutdown is enabled through valve deactivation, which is performed by a compact switchable tappet. Cylinder de-activation occurs on the right-hand bank only, which allows the engine to run as a perfectly balanced inline 6-cylinder. The system deactivation and reactivation has a quick response time and the oil system and solenoid layout allows valve switching capability at up to 6000 rpm. In May 2001, GM announced that it will implement Displacement on Demand in its trucks and SUVs beginning in 2004.

Direct Injection Gasoline

Using a direct-injection gasoline combustion system provides an increase in engine power and also improves fuel economy and cold-start hydrocarbon emissions. The multiple injection set-up also improves emissions and performance through faster catalyst light-off. The single fluid high-pressure fuel injector is centrally located in the combustion chamber, and sprays the fuel vertically down to the piston.

Variable Cam Phasing

The use of variable cam phasing helps the Northstar XV12 achieve 90 percent of its maximum torque at 1500 rpm, improves combustion stability at idle, improves fuel economy by reducing pumping losses and can be used to speed up catalyst light-off to significantly improve emissions. It provides internal exhaust gas recirculation (EGR), which is more reliable and cost-effective than an external EGR set-up.

Variable Intake Manifold

The Northstar XV12's three-stage variable induction system with tuned primary and secondary pipes results in a flat torque curve. It's a simple, compact and reliable design. Electric variable intake valve actuators enable rapid changes in manifold geometry over conventional pneumatic actuators.

Rear Chain Timing Drive

Many of the engine's accessories are run off the rear chain timing drive, creating opportunities for better packaging by eliminating the need for a front engine accessory drive and reducing the engine's overall length, as well as the height of its front end. The robust yet quiet-running chain drives the engine's camshafts, high-pressure fuel pump, oil pump, and hydraulic power-assist steering pump, and also has the potential to drive the water pump and air conditioning compressor. 36,000-Mile Oil Change Interval The Northstar XV12 is designed for 36,000-mile intervals between oil changes. This is achieved through a combination of improved oil sensors and monitors, reduced oil consumption, oil cooling and a larger oil sump capacity.

The Northstar XV12 project began in late 1999. GM enlisted Cosworth Technology to assist in the project. GM developed the technologies for all the major systems and Cosworth Technology provided the engineering integration of these technologies.

(August 20, 2001)

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