A vehicle powertrain includes an engine having an air intake system and an exhaust system. A turbocharger includes a turbine section connected to the exhaust system and a compressor section connected to the air intake system. A wastegate is disposed in the exhaust system and movable between an open and a closed position by an actuator system. The actuator system includes a gear mechanism for moving the waste gate from a closed to an open position and including a pair of noncircular gears.