Twincharger

Twincharger is a drivetrain configuration for internal combustion engines that combines a supercharger and a turbocharger to force air into the engine. The aim is to deliver strong low-end torque and high-end power from a relatively small engine by using the supercharger for immediate boost and the turbocharger for high-speed efficiency.

Most twincharger systems are sequential. A mechanically driven supercharger (often Roots- or screw-type) provides boost at low engine speeds. When the engine reaches a sufficient speed, the exhaust-driven turbocharger begins to contribute and air is routed through valves and ducts to the turbo for additional pressure. Some designs place the compressors in series with limited bypassing, while others use a bypass or clutch to switch or share load between the units. The control strategy is critical to avoiding fighting pressure from the two compressors and to controlling response.

Notable production applications have included Volkswagen Group's small-displacement 1.4-liter engines branded as Twincharger, which used a mechanical supercharger paired with a turbocharger to broaden the torque curve. The concept has also been explored by other manufacturers and in concept cars, though it remains less common than either turbocharging or supercharging alone due to added complexity and cost.

Advantages of twincharging include rapid response at low engine speeds, higher specific output from smaller engines, and improved driveability. Drawbacks are mechanical complexity, higher manufacturing and maintenance costs, packaging challenges, and potential reliability concerns. In recent years, many automakers have favored turbocharging in combination with mild electrification instead of twincharging, limiting its mainstream adoption.

See also: turbocharger, supercharger, forced induction.