New piston designed for EGR engines

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Federal Mogul’s Monosteel piston has been designed to withstand the harsh combustion conditions created by EGR engines. The company’s engineers used high-tech computer imaging to track oil movement in the crown’s oil gallery, and designed a gallery that’s larger than in previous products.

With all the hype of Exhaust Gas Recirculation (EGR) engines and the economic impact of the October emissions deadline, the technology itself and questions of cost and reliability have gotten most of the attention.

One area where little attention has focused is the place where the technology comes together – the combustion chamber.

The engineers at Southfield, Mich.-based Federal Mogul, a company that accounts for pistons in half the heavy-duty engine brands on the road, say the toxic soup created by EGR engines’ lower peak combustion temperatures will wreak havoc on conventional, articulated pistons. So they’ve redesigned their heavy-duty piston to withstand the new chemical chaos.

The EGR process creates an “acid cocktail,” explains Keri Westbrooke, director of heavy-duty product technology for the company. Rings, liners and pistons will be exposed to increased levels of sulfuric, acetic, nitric and formic acids.

Federal Mogul’s new, all-steel piston, called Monosteel, is designed to withstand these adverse elements, and will replace the company’s current, aluminum and steel, articulated piston. It consists of a light steel cylinder and heavy steel crown, which are fused together through a proprietary, spinning, friction-welding process.

The new piston resists corrosion better and also has improved cooling efficiency, says Federal Mogul. The company’s engineers used high-tech computer imaging to track oil movement in the crown’s oil gallery, and designed a gallery that’s larger than in previous products.

The Monosteel, reportedly will be about the same weight as an aluminum/steel articulated piston, and will be cheaper to make, because it uses the same materials and the design is bushless.

Looking ahead, the company says future rings and liners will also use new materials to cope with the corrosion issue. Future linings might be made of higher-strength alloy cast iron. And once tougher emissions standards go into effect in Europe, the linings may even be made of compacted graphite. Rings will probably chrome-faced.

All the changes are designed to keep engine life expectancy in new EGR engines at the same place as current engines, says Federal Mogul – even as combustion conditions become more severe.

The company says it has already signed a five-year, $100-million agreement to supply Monosteel pistons for an undisclosed engine planned for production in 2003.