Engine

441 kW (600 PS) at an engine speed of 6,000 rpm, 800 Nm (590.0 lb-ft) of torque between 2,200 and 4,500 rpm – the 4.0 l (1.06 US gal) V8 in the new Audi RS Q8 delivers impressive RS performance. The turbocharged gasoline engine with direct injection allows the large SUV coupé from Audi Sport to sprint from 0 to 100 km/h (62.0 mph) in just 3.8 seconds or to 200 km/h (124.3 mph) in 13.7 seconds. At 250 km/h (155.3 mph), it is electronically curtailed; with the dynamic package plus, the RS Q8 can drive at up to 305 km/h (189.5 mph). In the WLTP cycle, the power unit certified to Euro 6d-TEMP consumes an average 12.1 liters of fuel per 100 kilometers (19.4 US mpg), equivalent to 276 grams of CO₂ per kilometer (444.2 g/mi).

Full sound: V8 firing order and dual exhaust system

The 4.0 TFSI develops a sporty and voluminous sound with its firing order 1-3-7-2-6-5-4-8. As is typical for the RS models, the dual exhaust system features an impressive oval tailpipe on each side. The driver can influence the engine’s sound via the Audi drive select system. The optional RS sport exhaust system with black tailpipe trims offers an even more spectacular sound.

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 weighs just 39.1 kilograms (86.2 lb). A 150-micrometer-thick iron coating is applied via plasma spraying to the cylinder working surfaces, which minimizes friction and wear. An electronic valve arranged centrally in the inside V also regulates the map-controlled piston spray nozzles as required for piston cooling.

A fully variable pump drives the oil circuit. It is split into two separate oil galleries – one for the engine block and one for the cylinder heads. This layout ensures a reliable supply of oil even under the extreme lateral and longitudinal acceleration that the Audi RS Q8 is capable of achieving. The variable water pump is used only at 80 degrees Celsius so that the coolant, which has not been flowing so far, heats up quickly. The chains of the valve gear are driven by a geared intermediate shaft. This also drives the water pump. To ensure that the cylinders are filled properly at all times, intake and exhaust camshafts can be adjusted by 50 degrees. Each cylinder bank drives a high-pressure fuel pump for the direct injection, which builds up pressure of up to 250 bar. The injectors, located in the center of the combustion chamber, inject the fuel through seven holes, following special injection strategies depending on the requirements, from cold start to full load.

Pure power: 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 turbocharger supplies one cylinder bank with up to 1.4 bar of pressure (relative). This high value results in an excellent filling ratio of the cylinders, meaning that more air is available for the combustion of fuel. This results in high engine output and improved efficiency. The cylinder heads have the intake side on the outside and the exhaust side on the inside. The turbochargers and their optimized air-to-air heat exchanger are located in the 90-degree inside V of the cylinder banks rather than in the usual location outside next to the crankcase. This layout enables short gas flow paths with minimal flow losses and spontaneous engine response. Elaborate and effective insulation of hot parts ensures thermally stable conditions in the inside V. The compression ratio is 9.7:1.

Performance and efficiency: mild-hybrid system (MHEV) and cylinder on demand (COD)

The V8 twin turbo in the new RS Q8 combines performance and efficiency. Its mild-hybrid system (MHEV) is based on a 48-volt main electrical system. At its core is a belt alternator starter connected to the crankshaft. During deceleration and braking, it can recover up to 12 kW of power and feed it into a compact lithium-ion battery as electricity. If the driver takes their foot off the accelerator at a speed between 55 km/h and 160 km/h (34.2 to 99.4 mph), the drive management selects one of two solutions depending on the driving situation and the current setting of the Audi drive select dynamic handling system: The new RS Q8** either recuperates or glides for up to 40 seconds with the engine off. The belt alternator starter starts the engine within fractions of a second when the accelerator is actuated. MHEV technology allows start-stop mode from a residual speed of 22 km/h (13.7 mph). The mild-hybrid system is connected to the camera sensors for even greater efficiency. When stopped, the engine starts up while the brake pedal is still depressed as soon as the front camera detects that the vehicle in front of the RS Q8 is beginning to move.

The interplay of the MHEV components improves ride comfort and also has the potential to reduce fuel consumption in everyday driving by as much as 0.8 l/100 km.

The cylinder on demand (COD) system is another weapon in the vehicle’s armory when it comes to efficiency. At low through intermediate load and speed, it deactivates cylinders 2, 3, 5 and 8 in the high gears by switching off injection and ignition and allows the intake and exhaust valves to be closed at the same time. During four-cylinder operation, the operating points of the active cylinders thus shift to higher loads and map points with better efficiency, while the deactivated cylinders run largely loss-free, like gas springs. They are reactivated instantly when the driver presses the accelerator pedal. Each switchover takes mere milliseconds and is virtually undetectable. 

* 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.

All terms in blue in the text are explained in detail in the technology lexicon at www.audi-mediacenter.com/en/technology-lexicon.

The specified equipment, data and prices relate to the model range on offer in Germany. Subject to changes and errors. Figures on the fuel consumption and the CO₂-emissions (found from page 2 onwards) vary in case of given ranges depending on the used combination of wheels/tires.