Variable Valve Timing Delivers Consistent Efficiency For Chevrolet

by Chevrolet in the News on June 24, 2011

2011 Chevrolet Cruze image

Thanks to an innovative powertrain technology called variable valve timing (VVT), Chevrolet engines breathe better, so people can, too. VVT delivers outstanding drivability, along with low-emissions fuel efficiency, by continuously adjusting the opening and closing of the engine valves to help get air into the combustion chamber and exhaust gases out.

Chevrolet’s VVT system relies on a hydraulic mechanism to adjust the camshaft’s position relative to the crankshaft, allowing the valves to be opened and closed earlier or later in the combustion cycle. The system provides an optimal mix of performance and fuel economy, with reduced emissions and smoother idle control as well. And on dual overhead cam engines, like the 3.6-liter V6 in the Chevy Camaro, the intake and exhaust cams can be adjusted independently so that valve overlap—the period during which the intake and exhaust valves are open at the same time—can be optimized as well.

According to, that explains how the V6 Camaro can still achieve 30 mpg on the highway despite packing a full 312 hp.

Not that engine size matters, according to Sam Winegarden, GM’s executive director of Global Engine Engineering. Said Winegarden: “Whether powered by four, six or eight cylinders, virtually every current Chevrolet car and truck from the compact Aveo and Cruze to the full-size Suburban SUV features variable valve timing (VVT) on its engine to optimize its breathing.

“Bookending the Chevy lineup, the VVT-equipped Cruze Eco achieves an EPA estimated 42-mpg highway while the full-size Silverado XFE pickup is estimated at 22 mpg highway, both of which are best-in-class figures for their respective segments,” he added. “In fact, the 2011 Cruze Eco is the most fuel-efficient gasoline-fueled vehicle in America.”

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