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Wolfsburg, 29 August 2005 - At the International Motor Show (Cars) in Frankfurt, Volkswagen is presenting to the general public a ground-breaking innovation in the drive sector: The world’s first twin-turbocharged FSI engine – the “Twincharger”. The compact 1.4 litre direct-injection engine develops up to 125 kW / 170 PS and has a maximum torque of 240 newton metres in the range from 1750 to 4500 rpm thanks to the combination of an exhaust turbocharger with a mechanically driven compressor.

The 1.4 litre engine delivers a power output of 90 kW / 121 PS per litre, representing a peak value for a series production four-cylinder engine. Furthermore, the “Twincharger” delivers a torque corresponding to a naturally aspirated engine with a swept volume of approx. 2.3 litres. And its fuel consumption is around 20 percent lower.

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The Volkswagen engine developers selected a compressor with a mechanical belt drive in order to increase the torque at low engine speeds. This is a supercharger unit based on the Roots principle. One special feature of the compressor used is its internal step-down ratio on the input end of the synchronisation gear pair.

The exhaust turbocharger also kicks in at higher engine speeds (with wastegate control). The compressor and exhaust turbocharger are connected in series in this case. The compressor is operated by a magnetic clutch integrated in a module inside the water pump. A control flap ensures that the fresh air required for the operating point can get through to the exhaust turbocharger or the compressor. The control flap is open when the exhaust turbocharger is operating alone. In this case, the air follows the normal path as in conventional turbo engines, via the front charge-air cooler and the throttle valve into the induction manifold.

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