Audi Uppowers 2.0L TDI Diesel for A3 Concept

18 May 2008

Audi is showcasing an A3 TDI diesel study car at the upcoming 27th annual Lake Wörther Tour being held at the end of May in the Austrian province of Carinthia. An uppowered 2.0L TDI engine in the A3 TDI clubsport quattro delivers 165 kW (224 hp) and produces 450 Nm (331.90 lb-ft) of torque available from 1,750 rpm. The show car accelerates from 0 to 100 kph (62.14 mph) in 6.6 seconds and has a top speed of 240 kph (149.13 mph).

The Audi A3 TDI clubsport quattro.

The engineers took as a basis the undersquare engine (bore x stroke = 81.0 x 95.5 millimeters) with an output of either 103 kW (140 hp) or 125 kW (170 hp), depending on the configuration, and added to it an optimized turbocharger. The design of its blades allows it to supply more air; as in the series-production version, the variable geometry of the turbine’s blades ensures spontaneous response.

Fuel injection is handled by a common-rail system with piezoelectric injectors and eight-hole nozzles. The high-precision metering of as many as five injections of fuel per power stroke has the effect of audibly reducing the noise level. The system operates at a pressure of 1,800 bar, resulting in extremely fine atomization of the fuel which, together with the revised piston geometry, makes the combustion process highly efficient.

The engine’s intake manifold houses swirl flaps that generate a tumbling action in the inflowing air; electric motors regulate the flaps’ position so that this tumbling motion is always suited to the current load and engine speed. Two balancer shafts in the engine reduce the degree of vibration in the crank drive. The drive unit for the belt that propels the two camshafts has also been reworked with a view to improving the engine’s acoustics.

In this high-performance 165 kW (224 hp) variant, the 2.0 TDI unit is still able to make use of a high proportion of recirculated and sharply cooled exhaust gas to achieve cooler combustion with lower oxygen levels, resulting in a substantial reduction in engine-out NO_x emissions. The four-cylinder power unit already complies with the limits of the Euro 5 emissions standard, which is not due to come into force until September 2010.

The efficient two-liter engine attains a power-to-displacement ratio of 83.8 kW (113.8 hp) per liter, and torque-to-displacement ratio of 228.7 Nm (168.68 lb-ft) per liter.

The engine in the Audi A3 TDI clubsport quattro is mated to a compact, transverse-mounted six-speed transmission whose casing is made from lightweight magnesium. The transmission ratios have been adjusted and the components reinforced to make allowance for the TDI engine’s extremely high performance.