LMP Does Not Stand For "Limp" - Caddy LMP 02has Hard Twin Turbo Northstar Engine
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Cadillac LMP 02 Technical Insights: Northstar Engine Development
SEBRING, Fla. - Pose the question, "What's new?" to GM Racing engineer Ed Keating, and you get a succinct reply: "Everything."
RACE-PROVEN NORTHSTAR LMP ENGINE IS REVISED FOR 2002
Keating leads the team of engineers and technicians that produces the prime mover for the Cadillac LMP 02 - the twin-turbocharged 4.0-liter (244ci) Northstar V8 racing engine. While the changes in the body and chassis of the second-generation Le Mans Prototype are apparent, the modifications to the heavily revised powertrain are virtually invisible.
"We have made substantial changes in internal components and specifications for the 2002 season, but the engine's external appearance is generally unchanged," Keating said. "After evaluating the alternatives in displacement, induction systems, maximum boost and air restrictor sizes, the engine group decided to continue development of the turbocharged Northstar V8 that has proven itself over the last two seasons of competition."
ACO RULES SPECIFY MAXIMUM BOOST AND INLET RESTRICTORS FOR LMP ENGINE
The Automobile Club de L'Ouest (ACO) rules that govern the 24 Hours of Le Mans and the American Le Mans Series (ALMS) achieve performance parity among different types and sizes of engines by specifying inlet air restrictors and maximum turbocharger boost. Under the ACO formula, the 4.0-liter Northstar V8 is limited to 1500 millibars absolute manifold pressure (equivalent to 7.5 psi boost pressure) and its air intake is regulated by two 32.4mm (1.28-inch) diameter orifices.
"The ACO regulations do a very good job of producing equivalency between naturally aspirated and turbocharged engines with a variety of displacements," Keating said. "However, turbocharged V8 engines have enjoyed great success at Le Mans in recent years, and the architecture of both the production Northstar V8 and its racing derivatives is well suited to this particular configuration.
PROVEN ENGINE ALLOWS TEAM CADILLAC TO FOCUS ON CHASSIS DEVELOPMENT
"Another factor in the decision to continue development of the turbocharged Northstar V8 was time management," Keating continued. "There are already enough variables with the introduction of an all-new chassis. The Northstar V8 is a proven, reliable powerplant that will allow the team to focus on car development rather than powertrain issues."
The Northstar LMP engine is a product of GM's global motorsports program. It has close ties to the 4.0-liter naturally aspirated engines used by Opel in the German Touring Car Masters (DTM) road racing series and to the methanol-burning naturally aspirated 3.5-liter Chevy Indy V8 engine that is being introduced in the Indy Racing League (IRL) oval-track series in 2002. All three racing engines are based on GM Powertrain's Premium V platform.
NORTHSTAR V8 BENEFITS FROM IRL AND DTM MOTORSPORTS PROGRAMS
"In 2001, we introduced a 180-degree crankshaft in the Northstar LMP engine that was based on a design originally developed for the IRL series," Keating reported. "This year we are incorporating cylinder head and valvetrain developments from the Opel DTM program that suit the operating range of the Northstar LMP engine.
"We are also pursuing improved performance and fuel efficiency through friction reduction, induction system tuning, refinements in engine calibration and enhancements in oil scavenging to minimize parasitic windage losses," Keating added.
GM PREMIUM V ENGINE FAMILY PROVIDES PLATFORM FOR LMP, DTM AND IRL RACING ENGINES
The LMP, DTM and IRL racing engines share their fundamental design with the family of production Premium V engines that power Cadillac Seville, Eldorado and DeVille models. The production and racing engines have similar attributes, including lightweight aluminum block and cylinder head castings, four-valve combustion chambers, chain-driven dual overhead camshafts and electronic engine management. They also share the same architecture, including a 90-degree V angle and 102mm cylinder bore centerlines. In the Cadillac LMP and IRL applications, the engine is a fully stressed chassis member that is subjected to suspension and aerodynamic loads.
COMMON ENGINE ARCHITECTURE IS KEY TO EFFICIENT USE OF RESOURCES
"The Premium V engine program demonstrates how General Motors is able to marshal its global resources to adapt a common engine platform to the unique requirements of three different racing series," said Joe Negri, GM Racing IRL/Road Racing Group manager. "Using a common engine architecture in several racing series allows GM Racing to respond quickly to new opportunities while controlling overall costs.
"The common elements in the ALMS, DTM and IRL engine programs also promote synergy between GM operating units in North America and Europe," Negri added. "This engine program demonstrates how GM uses motorsports to achieve its business objectives in specific markets."
NEW SIX-SPEED SEQUENTIAL TRANSMISSION
The Northstar LMP engine is paired with a new six-speed sequential gearbox in 2002. Paddles mounted on the steering wheel activate gear changes through a pneumatic shifting mechanism. This system allows the driver to shift gears without moving his hands from the wheel.
"The pneumatic shifter is completely self-contained," said chassis designer Nigel Stroud. "Unlike many hydraulically operated systems, it does not require oil pressure from the engine. Consequently we believe this air-operated system offers advantages in both reliability and maintenance."
Two years of continuous engine development have pushed the Northstar V8's output to 600 horsepower.
ENGINE DEVELOPMENT PROGRAM FOCUSES ON POWER, RELIABILITY AND FUEL EFFICIENCY
"The Northstar engine program has made impressive progress, and we fully expect this steady improvement to continue," said Cadillac LMP Program Manager Jeff Kettman. "Working with our development partners, Ed Keating and his group have produced an extremely reliable engine package. With the enhancements that they are introducing this year, we anticipate further improvements in outright speed while maintaining the reliability and fuel efficiency that are absolutely essential in endurance racing."
From the winding road courses of the DTM and the high-speed ovals of the IRL to the magnificent sweeping turns of Le Mans, GM's extended family of Premium V-based racing engines is turning fast laps - and turning heads.