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Andy
sent me this link for this article
that he wrote about (above)
GM's Innovative Northstar XV12 Concept Engine Showcases Future Technologies
in a Compact, Fuel Efficient Package
8/20/01 5:57 AM
Source: PR Newswire
PEBBLE BEACH, Calif., Aug. 20 /PRNewswire/ -- General Motors' (NYSE:
GM) 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.
"The Northstar XV12 provides a realistic look at what could power
an assault on the high-end, premium automotive segment," said Fritz
Indra, GM Powertrain executive director of advanced engineering. "At
the same time it showcases a wealth of new technologies under development
at GM Powertrain, many of which will eventually find their way into GM
engines of all shapes and sizes."
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.
"The packaging was probably the biggest challenge we faced, because
from the outset we wanted to fit the V12 inside the package of a V8,"
said Steve Kowalk, GM Powertrain project manager for the Northstar XV12.
"We focused on keeping the size down to fit as many different types
of vehicles as possible, while maximizing displacement, and then using
Displacement on Demand to deliver the required power at all times. We
also minimized cylinder bore wall thickness to 7 millimeters and used
a rear cam drive to create a more compact package and enable a lower hoodline."
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.
GM Powertrain is a global producer of engines, transmissions, castings
and components for GM vehicles and other automotive, marine, and industrial
OEMs. Headquartered in Pontiac, GM Powertrain has operating and coordinating
responsibility for General Motors powertrain manufacturing plants and
engineering centers in North America, South America, Europe, and the Asia-
Pacific region. SOURCE General Motors Corporation
Copyright 2000, PR Newswire
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