Engine S63 TOP: Twin-Scroll

The designation twin-scroll describes an exhaust turbocharger with double-pipe turbine housing. In the turbine housing, the exhaust is routed to the turbine by 2 cylinders each separately. The so-called thrust charge is thereby utilized more. The exhaust flows in the turbine housing of the exhaust turbocharger are separately routed in spiral shape (scroll) to the turbine wheel.

The turbine is only rarely exposed to constant exhaust-gas pressure. At low engine speeds the exhaust gases arrive as pulsating pressure waves. This pulsation produces brief spikes in the pressure ratio at the turbine. Because higher pressures are accompanied by a simultaneously rise in operating efficiency, the pulsation enhances the effective supercharging pressure to increase the engine's torque generation.

To improve the gas exchange, the cylinders 1 and 6, 4 and 7, 2 and 8 and 3 and 5 are combined with one exhaust pipe each in the engine S63.

A wastegate valve is employed to limit the boost pressure.