Hyundai Touts Variable Valve Duration Tech

Hyundai Motor Group says its new engine “continuously variable valve duration” system is the first to adjust intake valve duration according to driving conditions.

Hyundai says the CVVD system responds to driving conditions to cut exhaust emissions 12% while improving performance and fuel efficiency by 4% and 5%, respectively.

The technology will debut later this year in Hyundai’s new Smartstream G1.6 T-GDi engine. The turbocharged 4-cylinder unit makes 180 hp and 195 lb-ft of torque. The powerplant will debut this autumn in the new Sonata turbo midsize sedan.

Competing variable valve control systems manage air intake by adjusting when the intake valve opens and closes, or how far it opens. But neither determines how long the valve stays open.

Under steady engine speed and low power demand, Hyundai’s CVVD system closes the intake vale at the middle of the intake cycle. This improves fuel efficiency by minimizing resistance causes by the compression cycle that follows.

But under high-speed conditions, CVVD system closes the intake valve later, just as compression begins. Hyundai says this improves responsiveness and power output.