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BMW finds a partner in torque

Kolbenschmidt-Pierburg does heavy lifting in new 7-series engine

What is Kolbenschmidt-Pierburg?
Headquarters: Dusseldorf, Germany

2000 sales: $1.7 billion

Employees: 12,000

Key products: Pistons, engine blocks, pumps, air management systems and bearings

Key customers: Audi, BMW, Ford, General Motors, Peugeot, Porsche and Volkswagen

FRANKFURT - BMW AG has entrusted one supplier with several roles on the 7-series' new V-8 engine. German engine parts maker Kolbenschmidt-Pierburg AG is responsible for the engine's:

  • Machined aluminum block

  • Pistons

  • Intake manifold system, which Kolbenschmidt-Pierburg developed and patented

  • Fuel pump

  • Bearings

  • Secondary air system

  • Exhaust components.

    BMW officials are reluctant to say they're outsourcing the project. But Kolbenschmidt-Pierburg is inching into business where few have strayed.

    "There is no general direction for outsourcing our engine work," said Christopher Schausberger, BMW's chief architect for the V-8. "Engine development is absolutely key to BMW. All layout and design for this engine is purely BMW."

    The shift

    Yet Kolbenschmidt-Pierburg's service to BMW is part of a larger industry shift toward increased supplier involvement in engine programs. As automakers pursue varied programs involving iron, aluminum, magnesium and synthetic materials, they are looking to suppliers to help them move quickly.

    General Motors, for example, has outsourced a complete manifold module for its Saturn Vue sport wagon and the Cadillac CTS. That module includes fuel rails, sensors, throttle bodies, hoses, actuators and the complete wiring.

    Engine blocks also are being increasingly outsourced to suppliers such as Kolbenschmidt-Pierburg, NEMAC and Teksid. Horst Bennig, a Kolbenschmidt-Pierburg board member, forecasts that his company's sales of engine blocks to automakers will double in the next three years.

    "The supplier can help the automaker save money," Bennig said. "In our case, we are working with many component materials, with aluminum, with magnesium, with plastics. The automaker typically has invested in one material. When the technology requires a change, it is easier for an external company to respond than for the automaker to do so."

    One example from Kolbenschmidt-Pierburg: new sleeveless cylinders created for the Volkswagen V-10 diesel. By including a silicon material in the metal of the engine block, the supplier can machine the cylinder holes down to a slick, ultra-low friction finish. That means the engines don't require cylinder liners. Liners usually run about $5 a cylinder to produce and install. Savings to VW: $5 times 10 cylinders, or $50 an engine.

    One-stop shopping

    Kolbenschmidt-Pierburg is the result of the 1997 union of German engine-part producers, Pierburg AG and KS Kolbenschmidt AG.

    Pierburg is a European supplier of pumps and air management systems; Kolbenschmidt produces pistons, blocks and bearings. Although the two entities continue to market themselves separately, they are owned by German conglomerate Rheinmetall AG.

    BMW's challenge to Kolbenschmidt-Pierburg was simple: Give the V-8 more torque. High torque, which is enhanced by the intake manifold design, is a trademark characteristic of BMW cars. The automaker wants its vehicles to accelerate with the responsiveness of a sports car, whether they are roadsters or sport-utilities.

    That tends to be easier for smaller cars with smaller displacement engines. But the large 7-series sedan, with its V-8, would take more throttle power. BMW wanted to avoid the typical power lull that occurs as an automatic transmission shifts into higher gears.

    The usual solution has been a variable intake manifold, a technology that can change the volume and speed of the air being fed to the engine based on engine speed. Such intakes have low-rpm and high-rpm operating modes. But that solution wasn't satisfactory for BMW. The problem, it argued, was that the feeling of torque would still sag momentarily as engine rpms changed with each gear change.

    Kolbenschmidt-Pierburg's solution: a patented continuously adjustable intake system.

    No valleys

    "It is a charging effect," says Wolfgang Reuter, managing director of Pierburg AG. "This is a very light way of turbocharging the engine. BMW wanted a very smooth acceleration for the 7 series."

    On the new system, the housing is made of magnesium to reduce weight. The interior plumbing that carries the air into the engine is plastic. The intake rotates up to 236 degrees, using an electric motor drive. The higher the engine rpm, the greater the rotation and volume of air intake. The system will hold its peak setting up to 3,500 rpm.

    That solution satisfied the BMW team. Although the results appear modest when the V-8's engine power is charted out, they have the effect of sustaining torque through the gear-change valleys of the six-speed automatic transmission. The technology was not so much a torque booster as a torque sustainer.

    "At each engine speed, you get the maximum torque possible," Reuter says.

    The 2002 BMW 7 series offers two

    V-8 powerplants: a 3.6-liter engine in the 735 that makes 272 hp; and a 4.4-liter unit in the 745 that makes 333 hp.

  • You can reach Lindsay Chappell at lchappell@crain.com

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