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TORQUE OF THE TOWN – AUDI S5 GAINS TDI POWER, 48 VOLTS AND AN EPC.

New V6 diesel powerplant in elegant Coupe and Sportback delivers stepless torque thanks to the electric powered compressor

  • Powerful 3.0 TDI engine with 347PS and 700Nm
  • 48-volt mild hybrid technology and electric powered compressor
  • Ideal combination of efficiency and performance

For the first time in its history, the Audi S5 now has a V6 diesel at its heart. Underpinned by mild hybrid technology, it equips the peak performer with impressive staying power between fill-ups and delivers even greater immediacy of response courtesy of an electric powered compressor. The 3.0 TDI engine, which will be introduced in both the S5 Coupé and the S5 Sportback in late 2019, now produces 347PS and delivers up to 700 Nm (516.3 lb-ft) of torque to the crankshaft, available between 2,500 and 3,100 rpm. This combination of power, torque and efficiency sets the S5 apart in this segment.

The 3.0 TDI in the S5 models is the most powerful version in the Audi V6 diesel engine line-up. Both the electric powered compressor (EPC) and mild hybrid (MHEV) systems are embedded in the standard 48-volt main electrical circuit. For the first time in the S5 TDI, a powerful 48–volt belt alternator starter is the heart of the mild hybrid system with maximum recuperation power of up to 8 kW. A DC/DC converter steps this voltage down for components in the 12–volt electrical system. A compact, air-cooled lithium-ion battery with a capacity of 0.5 kWh installed under the luggage compartment floor serves as the energy centre.

With these characteristics, the V6 diesel engine is the ideal power plant for agility, spontaneity, low fuel consumption and long range, with a suitably resonant sound to match.

Acceleration to 62mph in the S5 Coupé takes 4.8 seconds and and 4.9 seconds in the S5 Sportback, with both reaching their peak at an electronically limited 155mph.

The EPC: fast support for the turbocharger
The electric powered compressor in the Audi S5 TDI is new to this segment. It is located in a bypass downstream of the intercooler and thus close to the engine. From the outside, the compressor looks similar to a conventional turbocharger. A compact electric motor replaces the turbine wheel, however. With an output of up to 7 kW, it accelerates the compressor wheel to 65,000 rpm in approximately 300 milliseconds. It is activated whenever the power demand from the driver is high but the energy available in the exhaust flow for driving the compressor wheel is low. If this is the case, the bypass valve closes and directs the intake air to the EPC. The compressed air flows directly into the combustion chamber. This enables the driver to tap the full power of the 3.0 TDI instantly even at low engine speeds, whether passing another vehicle or accelerating out of a corner. Because the technology increases torque at the lower end of the rpm range, it provides for lower engine speeds and less frequent downshifts during relaxed driving. From a standing start, the new S models quickly move several metres ahead of comparable vehicles without an EPC.

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