Compressed air gives Volvo's turbo engines a boost

  • (Compressed air flow in green)

    (Compressed air flow in green)

  • (Compressed air flow in green)

    (Compressed air flow in green)  (Volvo)

Volvo has put a new spin on the turbocharged engine.

The 2.0-liter 4-cylinder diesel motor in its upcoming S90 sedan doesn’t just use a turbocharger to compress air into the cylinders for increased power, but also uses compressed air to give the turbo itself a boost.

Turbochargers are typically driven by only the exhaust gas exiting an engine, which takes some time to accelerate the turbine. This leads to what’s known as turbo lag, which is that moment right after you step on the accelerator pedal when not much happens, before the full effect of the boost kicks in.

Automakers have developed various measures to minimize the effect, including the combination of an engine-driven supercharger, which delivers boost at low engine speeds until the turbocharger takes over at high revs. Volvo currently offers an engine with this type of arrangement in several of its vehicles.

But its new PowerPulse technology approaches this issue in an even more novel way. It features an electric air compressor that fills a two-liter canister with filtered pressurized air, releasing it into the exhaust manifold in bursts or “pulses” whenever you step on the accelerator. This quickly brings the turbo up to speed, filling the gap and virtually eliminating lag, Volvo says.

You’ll have to take its word for it for the time being, because there are no plans to offer a diesel version of the S90 in the United States when it goes on sale here next year.