“Combustion behavior was a particular focus of the development work,” Audi explains. In addition to FSI direct injection, the 1.8 TFSI also uses indirect injection. This system injects the fuel at the end of the intake manifold near the tumble valves, where it is swirled intensively with the air. Indirect injection is used in the part-load range. It reduces fuel consumption and particulate emissions to such an extent that the four-cylinder engine already complies with the limits of the future Euro 6 standard, which does not enter into force until 2015.
The rail pressure of the FSI system has been increased from 150 to 200 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. To further optimize gas exchange, the valve control system has been given greater operating freedom. The Audi valvelift system, which adjusts the lift of the valves in two stages, is active on the exhaust side. The two camshafts can be adjusted through 30 or 60 degrees of crankshaft angle.
It is timely that Audi updates the 1.8 TFSI lump. The original 160bhp powerplant is getting a bit long in the tooth. It's latest rival, the Mercedes C 250 Coupe, produces 204 bhp from its 1.8 litre turbocharged engine. It looks like Audi still have some catching up to do.