Drive system

420 kW (571 PS), 800 Nm (590 lb-ft) of torque between 2,000 and 4,500 rpm ((combined fuel consumption in l/100 km: 11.4–11.3* (20.6–20.8 US mpg); combined CO₂ emissions in g/km: 260–258* (418.4–415.2 g/mi)) – the four-liter V8 with its twin turbochargers provides concentrated power, awesome power delivery and exhilarating performance. Its specific power output is 142.9 PS per liter of displacement, meaning that each PS has to move only around 4 kilograms (8.8 lb) of unladen weight. The specific torque is also impressive: For each kilogram of weight, there are 2.855 Nm (2.1 lb-ft) available for dynamic acceleration. Top speed has been electronically limited to 250 km/h (155.3 mph). As a result, the high-performance powerplant offers not only maximum smoothness, but also the certainty that ample power is available for any situation.

The V8 has a conventional 90-degree bank angle and a displacement of 3,996 cc (bore x stroke: 86.0 x 86.0 millimeters (3.4 in x 3.4 in)). Its crankcase is made of cast aluminum and weights just 39.1 kilograms (86.2 lb). A fully variable pump drives the oil circuit that is split into separate galleries for the engine block and the cylinder heads. This innovative layout guarantees a reliable supply of oil even under extreme lateral and longitudinal acceleration.

The valves are operated via chains that are driven by the crankshaft via an intermediate shaft. The engine features concentrated high-tech solutions in all areas. To ensure that the cylinders are filled to the optimum degree at all times in every operating situation, intake and exhaust camshafts can be adjusted by 50 degrees. Each cylinder bank is supplied with fuel by a separate pump that builds up pressure of up to 250 bar. The injectors, located in the center of the combustion chamber, spray the fuel out of seven holes, following special injection strategies depending on the requirements, from cold start to full load.

Powerful: the two twin-scroll turbochargers

The immense torque that the 4.0 TFSI already produces at low engine speeds is all thanks to the two twin-scroll turbochargers. Each turbo supplies a cylinder bank with a relative boost pressure of 1.8 bar. The cylinder heads have the intake side on the outside and the exhaust side on the inside. Accordingly, the two turbos are housed near to the exhaust valves in the engine’s inner V, with the intercooler housed upstream of the engine. The preliminary and main catalytic converters are located very close to the engine so that they reach their operating temperature swiftly after the engine is started. The new Audi S8** is equipped with two gasoline particulate filters and is certified in accordance with the latest emission standard EU6DG.

Efficient and comfortable: the mild hybrid system

The 4.0 TFSI is the perfect blend of emotion, performance and efficiency. Its mild-hybrid system (MHEV) that is based on the 48-volt main electrical system of the new S8** can reduce fuel consumption by up to 0.8 liters (0.2 US gal) per 100 kilometers (62.1 mi) while also increasing the ride comfort. The core of the MHEV system is a belt alternator starter (BAS) connected to the crankshaft. During deceleration, it can recuperate up to 8 kW of energy. This electrical energy is stored in the additional lithium-ion battery, from where it is dynamically distributed to the consumers in the electrical system. The lithium-ion battery is located in the luggage compartment under the loading floor of the S8** and has an energy content of 0.47 kWh.

If the driver takes their foot off the accelerator at a speed between 55 and 160 km/h
(34.2 and 99.4 mph), the drive management selects one of three solutions depending on the driving situation and the current setting of Audi drive select: The new Audi S8** can recuperate, roll at idle or coast with the engine deactivated for 40 seconds. The BAS restarts the engine for acceleration. This can be particularly fast-acting or very harmonious depending on the situation. MHEV technology allows for start/stop operation from as low as 22 km/h (13.7 mph). When stopped, the engine also restarts while the brake pedal is still depressed as soon as the vehicle in front of the Audi S8** begins to move. The cylinder on demand system, which deactivates individual cylinders in low-load operating situations, is another efficiency element. It can reduce fuel consumption by several tenths of a liter per 100 kilometers in real-life use.

Highly emotional: the sound

Its unusual 1-3-7-2-6-5-4-8 ignition sequence gives the 4.0 TFSI a sound that is at once highly sophisticated and sportily voluminous. In typical S model style, the dual-branch exhaust system terminates in two tailpipes on both the left and right. The driver can influence it via the Audi drive select system. In the “dynamic” profile, the electric flap that is positioned in front of the left auxiliary silencer opens, and the sound becomes even more full-bodied and impressive. So that the engine sound remains highly emotional at all times, the Audi S8** is equipped with the Active Noise Cancellation system  as standard.

Fast and precise: the eight-speed tiptronic

In the new Audi S8**, power is transmitted via an eight-speed tiptronic. The automatic torque converter transmission changes gears quickly and almost imperceptibly and impresses thanks to a high degree of efficiency. The driver can choose to have it operate automatically in modes E, D and S or intervene himself or herself, in which case the selector lever commands are transmitted purely electrically. The revised transmission control detects stop-and-go traffic and prevents unnecessary gear changes in these situations.

For operation in conjunction with MHEV technology, some modifications have been made to the tiptronic. When the new S8** is coasting or rolling at idle, a clutch in the central transmission opens and interrupts the power connection. An electric oil pump enables the tiptronic to engage the gear while coasting that will be needed at restart. Narrow springs at the multi-plate brakes in the gear sets separate the plates from one another and thus reduce drag torque.

* Fuel/power consumption and CO₂ emission figures given in ranges depend on the tires/wheels used as well as the selected equipment
** The collective fuel consumption values of all models named and available on the German market can be found in the list provided at the end of this press information.