Variable intake system (VIS)

Courtesy of HYUNDAI MOTOR AMERICA

VIS (Variable intake system) is a device which varies the length of intake manifold to generate maximum power at certain RPM. VIS lengthens intake manifold to improve the torque at low RPM when vehicle speed is low while it shortens intake manifold to raise torque at high RPM when vehicle speed is high. ECU controls VIS using RPM signal.