(SEOUL) 5 July 2019 – Future KIA Motors vehicles will feature world-first Continuously Variable Valve Duration (CVVD) engine technology. The innovation has been developed by Hyundai Motor Group, KIA’s parent company, and was revealed alongside the company’s new Smartstream G1.6 T-GDi engine – the first power unit to feature the technology.

CVVD optimises 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 4% boost in performance and a 5% improvement in fuel efficiency. Furthermore, the technology cuts emissions by 12%.

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

Innovation: Continuously Variable Valve Duration

Until now, an internal combustion engine’s performance and efficiency have been governed by variable valve control technology that adjusts the timing of valve opening and closing and depth of the valve’s opening. Eengine power is produced through the fuel intake-compression-expansion-exhaustion cycle.

Typical variable valve control technologies manage the timing of the valve’s opening and closing (as in Continuously Variable Valve Timing – 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 the length of time that a valve stays open.

When the vehicle maintains 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 maximise the amount of air used for the explosion, enhancing torque to improve acceleration.

Smartstream G1.6 T-GDi Engine

Unveiled alongside the new CVVD technology is KIA’s new Smartstream G1.6 T-GDi engine, a four-cylinder in-line gasoline turbo unit producing 180 ps and 265 Nm torque. The new powertrain is the first to utilise the new CVVD technology and also features Low-Pressure Exhaust Gas Recirculation (LP EGR) to further optimise fuel efficiency.

The exhaust gas recirculation system returns some of the hot gases produced by the engine to the combustion chamber, producing a cooling effect and reducing the emission of nitrogen oxides. The G1.6 T-GDi also features a low-pressure system that redirects the burnt emission gas to the front of the turbocharger compressor, rather than the intake system, to increase efficiency under high load conditions.

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 or pressure, surpassing the 250 bar of KIA’s existing T-GDi engine. In addition, engine friction is reduced by 34% with the application of low-friction moving parts.