Variable Nozzle Turbines(VNT) and Variable Geometry Turbines(VGT) are turbochargers designed to alter the exhaust flow in the housing to maximise performance.
In a VNT or VGT turbo, a row of vanes controls the exhaust flow to match the requirements of the engine for it to operate optimally. At a lower engine speed, the vanes will be in close position to restrict the airflow from the exhaust through the turbine housing, increasing boost pressure. As the engine speed increases gradually, the moveable vanes open at the same speed as the engine. The precise movement of the variable nozzle vane maximizes the exhaust gas flow, thereby avoiding turbo over spin and maintaining the boost pressure required by the engine.
Key benefits of VNT/ VGT :
• Lighter engine package due to engine downsizing
• Delivers more power across a wide range
• Improved fuel efficiency
• Better torque characteristics
• Improved transient response
• Lower emissions