twincharging

Twincharging is an automotive engineering approach in which both a turbocharger and a supercharger are fitted to a single internal combustion engine to boost air intake across a broad range of speeds. The goal is to combine the immediate response of a supercharger at low engine speeds with the higher ultimate boost and efficiency of a turbocharger at higher speeds.

There are two principal implementations. Sequential (or series) twincharging uses a supercharger to provide boost at low RPM, helping to spool the turbo and reduce lag, after which the turbo supplies most of the boost as engine speed rises. In parallel twincharging, the two devices operate in a coordinated manner so their compressed air is combined before entering the engine, though this arrangement is less common and more complex to manage.

A common real-world arrangement uses a belt-driven Roots- or screw-type supercharger connected to the intake, with a turbocharger downstream of the supercharger or in a mixed-flow path. A bypass or clutch mechanism controls the flow, allowing the engine to rely on the supercharger at low RPM and switch to turbo boost as needed.

One emblematic example is the Volkswagen Group’s 1.4-liter TSI Twincharger, which combined a Roots-type supercharger with a small turbocharger to deliver strong low-end torque and high-end power in a relatively small displacement engine. Benefits of twincharging include improved low-end response and reduced turbo lag; drawbacks include increased mechanical complexity, larger packaging needs, higher cost, and greater parasitic losses, which can offset gains in certain operating regimes.

Today, twincharging remains relatively niche, with most modern engines employing turbocharging alone or combining turbocharging with mild electrification or other technologies to achieve similar outcomes.