September 13, 2011
Source: Audi of America
Ingolstadt,- Audi is expanding its engine lineup with a new, high-performance gasoline engine. The 4.0 TFSI, which is used in slightly different configurations in the S6, S6 Avant, S7 Sportback and S8, develops between 309 kW (420 hp) and 382 kW (520 hp), and as much as 650 Nm (479.42 lb-ft) of torque. The new V8 is a high-tech engine featuring numerous innovative solutions.
The youngest member of the large Audi family of V engines, the 4.0 TFSI shares all of their typical characteristics. It has the classic cylinder angle of 90 degrees, the chain drive for the four camshafts and ancillary units is on the back to save space, and the cylinder case is a cast aluminum-silicon alloy. This eight-cylinder unit is very light in weight, and its highly compact construction has resulted in its length being reduced to 497 mm (19.57 in).
Fuel is provided via Audi’s FSI direct injection system. Switchable flaps in the intake ports induce a rolling type of movement in the incoming air for improved combustion. Like almost every Audi engine, the new 4.0 TFSI also follows the principle of downsizing, where forced induction replaces displacement. One turbocharger per cylinder bank compresses the intake air. This is known as twinscroll technology, where the exhaust flows to the turbine wheel at high speed through two separate ports and enables torque to be developed extremely early, just above idle.
The two turbochargers and the intercooler are located in the inside V of the cylinder banks rather than in the usual location outside next to the crankcase. Audi has structured the cylinder heads in an innovative way. The exhaust side is on the inside, the intake side on the outside. This layout provides for compact dimensions and short gas paths with minimal flow losses, and the 4.0 TFSI reacts immediately to the gas pedal as a result. Sophisticated insulation of the hot components, in particular the exhaust manifold, stabilizes the thermal conditions in the inside V.
A further innovation is Audi’s cylinder management. In low to intermediate load and rev ranges, it deactivates two cylinders in each bank of the V8, reducing fuel consumption significantly. Thanks to a comprehensive package of innovative measures, the engine remains smooth and quiet during these phases. Shutting down the cylinders is virtually imperceptible. This cylinder management function is provided by the latest version of the Audi valvelift system by closing the intake and exhaust valves of the affected cylinders.
The 4.0 TFSI employs all the technologies from Audi’s modular efficiency platform. These range from measures to reduce friction, the start-stop system and the recuperation system to innovative thermal management that deactivates the water pump during the warmup phase to quickly bring the oil up to temperature. The new regulated oil pump varies the oil pressure in two stages, and the oil jet cooling for the piston heads is characteristic-controlled.
The new 4.0 TFSI provides for powerful performance in all of the large S models while at the same time demonstrating its high efficiency potential.
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