Chafing against engine friction

Friction is enemy No. 1 for powertrain engineers striving to meet rising fuel-economy standards.

"As engines get smaller, eliminating friction becomes even more important," says Dave Lancaster, a General Motors technical fellow who works at the automaker's powertrain engineering operations in suburban Detroit. "Every component in every engine is designed with all the analytical tools we have to reduce friction."

Lower friction enables engines to efficiently produce more horsepower per liter of displacement. And by re-engineering parts at modest cost, automakers can boost mileage without the massive investment of redesigning an engine. In the 2025 model year, each automaker's fleet miles per gallon must reach 54.5.

Engineers have made significant strides reducing friction. A GM four-cylinder engine from the early 1980s, called the Iron Duke, generated about 45 percent more friction than GM's current Ecotech four-cylinder -- even though the Ecotech engine has more moving parts, the automaker says.

Now, to further reduce friction, low-tech, off-the-shelf commodity parts such as piston rings, engine bearings, seals and oil pumps are evolving into premium hardware.

Suppliers are playing a big role. "Certainly there are many more areas where we can improve efficiency," says Wolfgang Rein, Mahle North America's senior vice president of r&d for engine systems and components. "Every small improvement counts when it comes to friction." Mahle is a leading piston and bearing manufacturer.

Here are five main engine components on which automakers and suppliers are working to reduce engine friction.

Coated, smaller bearings, right

Balance shaft with roller bearings

Valvetrain with polished tappets

Piston with small coated skirt, low-tension rings

Low-friction crankshaft seal

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