Reducing Emissions Boosts Performance.

• Position: Automobiles - Brief Article

A new automobile exhaust system reduces pollution and boosts engine power. It takes the place of multiple parts in the standard auto exhaust assembly, including the manifold, muffler, and catalytic converter. A study at Ohio State University, Columbus, showed the system increased overall engine performance by five percent while cutting emissions by 15%. Ahmet Selamet, associate professor of mechanical engineering, developed the perforated muffler manifold catalyst (PMMC) with his former graduate student, Kris Norman, now a technical specialist at Ford Motor Co.

According to Selamet, consumers want new engines to perform better, consume less fuel, create less pollution, and run quietly--all at the same time. Some of these features compete with each other during vehicle design. "When engineers incorporate a number of components into commercial exhaust systems to meet emissions and noise regulations, it's not unusual for the changes to cut engine performance by about 15%. For a six-cylinder, 200-horsepower engine, that means a loss of about 30 horses, and that's a lot of power." He says the new design will help vehicles recoup part of that loss.

"Any time we change the cross-sectional area of a pipe, it will reflect waves back to the source, in this case the engine," Selamet explains. The gases flow more easily through the new exhaust system because it contains shorter pipes with fewer internal divisions. In the...