The engines in Audi’s upgraded A5 family have redefined the standards for efficiency and sportiness. Even the completely redesigned 1.8 TFSI, which is the base engine, features the full extent of the company’s technological capabilities. The engineers have created advanced solutions in various aspects of technology to obtain surprisingly powerful performance with the least fuel consumption.
With four cylinders, this high-end engine displaces 1,798 cm3 and provides a powerful and constant 320 Nm (236.02 lb-ft) to the crankshaft between 1,400 and 3,700 rpm. At 3,800 rpm, the engine achieves a peak output of 125 kW (170 hp). With a manual transmission, the 1.8 TFSI accelerates the Audi A5 Coupé in 7.9 seconds from zero to 100 km/h (62.14 mph), with a top speed of 230 km/h (142.92 mph).
Even with that powerful performance, the engine only consumes 5.7 liters of fuel per 100 km (41.27 US mpg) on the average, corresponding to best-in-segment emissions of 134 grams of CO2/km (215.65 g/mile). Consumption has been slashed by 21 percent compared with the previous model engine, and the development work was particularly focused on combustion behavior. Aside from the FSI direct injection, the 1.8 TFSI also uses indirect injection, which is used in the part-load range. With this system, the fuel is injected at the end of the intake manifold near the tumble valves.
It is then swirled intensively with the air. It reduces the consumption of fuel as well as the particulate emissions to the extent that the engine already complies with the limits of the future Euro 6 standard, which will be enforced by 2015. The FSI system’s rail pressure has been raised to 200 from 150 bar. The direct injection system is active when starting off and at higher loads.
It can perform two or three individual injection operations per work cycle. Moreover, the valve control system has been provided with greater operating freedom in order to further optimize gas exchange. The Audi valvelift system, which adjusts the valves’ lift in two stages, is active on the exhaust side. Furthermore, the two camshafts can be adjusted through 60 or 30 degrees of crankshaft angle.