VVT (Variable Valve Timing), VTEC (Variable Valve Timing & Lift Electronic Control), VVT-i (Variable Valve Timing with intelligence), i-VTEC (intelligent VTEC), Dual VVT-i, CVVT (Continuously Variable Valve Timing) are all familiar valvetrain systems in today’s cars. Now the Hyundai Motor Group (HMG) adds a new one – CVVD or Continuously Variable Valve Duration (CVVD).

The world first technology, first mentioned at HMG’s International Powertrain Conference in October 2017, is being revealed at the Hyundai Motorstudio Goyang in Korea this morning. The Smartstream G1.6 T-GDi will be the first engine to have the technology and it will be used in future Hyundai and Kia models.

CVVD optimizes both engine performance and fuel efficiency while also being eco-friendly. The valve control technology regulates the duration of valve opening and closing according to driving conditions, achieving a claimed 4% boost in performance and a 5% improvement in fuel efficiency, while cutting toxic emissions by 12%.

How CVVD works
Typical variable valve control technologies manage the timing of the valve’s opening and closing (as in CVVT) or control the volume of air admitted by adjusting the depth of the opening (Continuously Variable Valve Lift – CVVL). Previous variable valve control technologies could not regulate valve duration, as the valve’s closing timing was subordinate to opening timing and could not respond to diverse driving situations. CVVD takes the technology in a new direction by adjusting how long a valve is open.

When the vehicle is maintaining a constant speed and requires low engine output, CVVD opens the intake valve from the middle to end of the compression stroke. This helps to improve fuel efficiency by reducing the resistance caused by compression. On the other hand, when engine output is high, such as when the car is driving at a high speed, the intake valve is closed at the beginning of the compression stroke to maximize the amount of air used for combustion, enhancing torque to improve acceleration.

Smartstream G1.6 T-GDi Engine
Unveiled alongside the new CVVD technology, the new Smartstream G1.6 T-GDi Engine is a V4 turbocharged petrol unit with 180 bhp/265 Nm output. Besides using the Group’s new CVVD technology, it also features Low-Pressure Exhaust Gas Recirculation (LP EGR) to further optimize fuel efficiency.

Additionally, the new unit has an Integrated Thermal Management System that quickly heats or cools the engine to an optimal temperature, and a strong direct spray system that achieves 350 bar, surpassing the 250 bar of the previous T-GDi engine. In addition, engine friction is reduced by 34% with the application of low friction moving parts.

“The development of the CVVD technology is a good example how HMG is strengthening our powertrain technology,” said Albert Biermann, President and Head of Research & Development Division at Hyundai Motor Group. “We will continue our innovation efforts to bring forth paradigm shifts and ensure sustainability of our business model.”