Audi has launched a 2.0 TFSI petrol engine with 140kW (190hp) with a claimed ground-breaking new combustion method. It will appear in the next generation A4.

Audi was the first manufacturer worldwide to bring the TFSI engine with turbocharging and direct injection into series production.

“We’re now taking a crucial step further with rightsizing,” said technical development chief Ulrich Hackenberg.

The reduction in displacement and engine speed can be optimally effective only if reasonably related to the vehicle class and the customers’ everyday use, he said.

“Rightsizing thus involves the optimal interplay of vehicle class, displacement, output, torque and efficiency characteristics under everyday conditions.”

The I4 engine develops 140kW (190hp) of power and 320Nm (236lb ft) of torque from a displacement of 1,984cc. The high torque is applied in a wide speed range of 1,450rpm to 4,400rpm and Audi claims “groundbreaking” low fuel consumption levels – less than 5l/100km (47 US mpg) in the NEDC.

At its core its principle is comparable to the Miller cycle but further developed:

  • The intake time has been significantly shortened (140° crank angle (CA) rather than 190 to 200° CA).

  • Owing to a higher boost pressure on the inlet side, the engine attains optimal cylinder charges despite the shorter intake time.

  • The intake valve also closes earlier – well before the bottom dead centre is reached. This lowers the medium pressure, allowing a high, efficiency-boosting compression ratio.

  • In the partial load range, an additional injection upstream from the intake valve yields an efficient mixture formation that is already complemented by the direct injection in the intake manifold and in the combustion chamber.

  • The Audi Valvelift System (AVS) on the inlet side allows a short intake time at partial load and a longer time at higher loads (full load: 170° CA).

Stefan Knirsch, head of engine development, said: “Thanks to this rightsizing approach, the new engine enjoys the consumption benefits of a downsizing engine in partial load operation, while at higher loads it has the advantages of a large displacement engine. The result is optimal efficiency and performance characteristics across the entire engine speed range.”

Beyond the new combustion method, the new engine, with a weight of only about 140kg (308.6lb), avails itself of other efficiency technologies. For example, the coolant flow is controlled so as to greatly shorten the engine warm-up time. Contributing to this benefit is also the exhaust manifold, integrated in the cylinder head. The consistent reduction of friction as well as the use of low-friction engine oil (0W-20) also increases efficiency.

Audi will launch its new generation of engines in next A4 and then in other model lines.