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FRANKFURT – It’s taken some 20 years, but cast-iron exhaust manifolds on gasoline engines are being replaced by lighter fabricated stainless steel manifolds, especially in China and Europe.
Today, as these fabricated manifolds become more robust and cost-efficient, they are gaining popularity for diesel engines, says Tim Jackson, chief technology officer for exhaust supplier Tenneco, based in Lake Forest, IL.
Within the past year, Tenneco has launched its first four fabricated manifolds for diesel-engine programs in Europe, and there’s plenty of interest among other potential customers, Jackson tells WardsAuto.
In North America, as gasoline direct-injection engines gain popularity, so are fabricated manifolds. Tenneco’s first fabricated manifold for the U.S. is for an unidentified hybrid-electric vehicle. “We’ll let our customer announce that,” he says.
The biggest driver behind the switch is reduced weight, which translates directly to improved fuel efficiency. A fabricated manifold is up to 50% lighter than a cast-iron module.
Diesel engines generally are about 30% more fuel-efficient than similarly sized gasoline engines. A fabricated manifold can boost diesel efficiency even higher.
“In some cases we take 10-15 lbs. (4.5-6.8 kg) out of the car, and that’s an incredible contribution to fuel economy and lighter weight,” Jackson says.
“Most auto makers have set a target to be 220 lbs. (100 kg) lighter on their next-generation cars,” he says. “Tenneco can bring 8% or so of that total number just with our emissions designs.”
