Sporty, elegant and open – The new Audi A3 Cabriolet

Engines

Audi is sending the new A3 Cabriolet to its market launch with three newly developed four-cylinder engines: one TDI and two TFSI engines. Shortly after the market launch, another TFSI will follow as an entry-level engine. Displacements range from 1.4 to 2.0 liters and their power from 103 kW (140 hp) to 132 kW (180 hp). All engines are turbocharged with direct injection; they impress with their high power, ample torque and low fuel consumption. All engines already satisfy the limits of the Euro 6 emissions standard. Driving performance is even better than in the previous model, while CO2 emissions are up to 13 percent lower.

Playing a large role here are technologies from the Audi modular efficiency platform. The start-stop system lowers fuel consumption by as much as 0.3 liters per 100 kilometers (0.08 US gallons per 62.14 miles). The innovative thermal management system helps the engine to reach its operating temperature quickly after a cold start – this shortens the phase of elevated friction losses.

The mounting position is identical for all engines. Their intake side is at the front of the car, and the upper axis is tilted twelve degrees to the rear. This solution, which comes from the Modular Transverse Matrix, offers great benefits together with the compact dimensions of the new engines. Developers shifted the front axle of the new Audi A3 Cabriolet far forward, which improves crash behavior, design and the distribution of axle loads.

The lightweight design philosophy of Audi also expresses itself in the engines. The new 1.4 TFSI with 92 kW (125 hp) weighs just 107 kilograms (235.89 lb). In the 1.8 TFSI, the thin-wall technology of the crankcase reduces weight by 2.4 kilograms (5.29 lb). In the 2.0 TDI clean diesel, relocating the balancer shafts into the engine block saves 3.0 kilograms (6.61 lb).

Audi A3 Cabriolet: Engines 

The 1.4 TFSI has 1,395 cc displacement (bore x stroke 74.5 mm x 80.0 mm
[2.93 in x 3.15 in]). It is available in two versions. In the base version, which will follow shortly after the market launch, it produces 92 kW (125 hp); its 200 Nm (147.51 lb-ft) of torque is available from 1,400 to 4,000 rpm. The sprint from 0 to 100 km/h (62.14 mph) takes 10.2 seconds, and the car has a top speed of 211 km/h (131.11 mph). Combined fuel consumption is just 5.4 liters per 100 kilometers (43.56 US mpg) (126 grams of CO2 per kilometer [202.78 g/mile])

In the version with COD, the 1.4-liter engine offers 103 kW (140 hp) and 250 Nm (184.39 lb-ft) of torque, the latter from 1,500 to 3,500 rpm. The compact four-cylinder engine enables sporty driving performance with 9.1 seconds for the standard sprint from 0 to 100 km/h (62.14 mph) and a top speed of 218 km/h (135.46 mph). Combined fuel consumption is just 5.0 liters per 100 kilometers (47.04 US mpg), which equates to 114 g CO2 per kilometer (183.47 g/mile). At market launch, the 1.4 TFSI COD will be available with the six-speed manual transmission.

Make two from four: COD technology in the 1.4 TFSI
A cutting-edge innovation is the cylinder on demand (COD) system in the more powerful of the two 1.4 TFSI engines. In the ECE cycle, it reduces fuel consumption by around 0.4 liters per 100 kilometers (0.11 US gallons per 62.14 miles), and in a moderate style of driving it offers as much as 20 percent fuel savings. It is an advanced development of the Audi valvelift system, and its operation is similar to that of engines in the brand’s large S and RS models.

At low and moderate load, and in coasting, the COD technology shuts down the second and third cylinders by closing their valves and deactivating fuel injection and ignition to them. To do so, the engine speed must be between 1,400 and 4,000 rpm and torque must be less than 100 Nm (73.76 lb-ft). Pins, which are extended electromagnetically, activate the so-called cam pieces – sleeves that each have two different cam profiles – on the camshafts. Then the so-called zero-lift profiles rotate over the valves; they do not activate the valves, and the valve springs hold the valves closed.

The switchover process takes just milliseconds. This increases efficiency in the active cylinders 1 and 4, because their operating points are shifted to higher loads. Even with a firing interval of 360 degrees, vibration of the 1.4 TFSI is still very low and the engine is quiet. When the driver pushes the pedal for fast acceleration, the cam pieces retract, and the shut-down cylinders are reactivated.

132 kW (180 hp): the 1.8 TFSI
At the sales launch of the new A3 Cabriolet, the 1.8 TFSI will be the most powerful engine – it too demonstrates the high-tech competence of Audi with numerous innovations. Its power output is 132 kW (180 hp), and its maximum torque of 250 Nm (184.39 lb-ft) is available between 1,250 and 5,000 rpm. The 1.8-liter engine, paired with the seven-speed S tronic, accelerates the open-top four-seater from a standstill to 100 km/h (62.14 mph) in 7.8 seconds, and it boasts a top speed of 242 km/h (150.37 mph). Its combined fuel consumption is 5.8 liters of fuel per 100 kilometers (40.55 US mpg), which corresponds to 133 grams of CO2 per kilometer (214.04 g/mile).

One of the key innovations in the 1.8 TFSI is the addition of indirect fuel injection. Under part load, it injects the fuel at the end of the induction manifold in the vicinity of the tumble flaps, where it is swirled intensively with the air. The improved mixture formation boosts fuel economy and reduces particulate emissions. FSI direct petrol injection, which develops up to 200 bars of pressure, is active at engine start and at higher loads.

Clean and Euro-6-conformant: the 2.0 TDI clean diesel
The 2.0 TDI clean diesel has been thoroughly redesigned in the new Audi A3 Cabriolet. It produces 110 kW (150 hp) and transfers 340 Nm (250.77 lb-ft) of torque to the crankshaft at engine speeds from 1,750 to 3,000 rpm. It accelerates the A3 Cabriolet from 0 to 100 km/h (62.14 mph) in 8.9 seconds and to a top speed of 224 km/h (139.19 mph). The average fuel consumption of the Euro-6 diesel engine, which will be paired with a six-speed manual transmission at market launch, is just 4.2 liters per 100 kilometers in the NEDC (56.00 US mpg), CO2 emissions are 110 g/km (177.03 g/mile).

In developing this engine, which has 1,968 cc displacement, the focus was on reducing emissions and optimizing for low friction. Among other actions, this was achieved by using roller bearings for the balancer shafts and reducing piston ring stress.

As in the 1.4 TFSI, the valve train is designed as a separate module, and the shafts are pressed into a separate bearing frame here. The camshaft adjuster can adjust the intake shaft by a crank angle of as much as 50 degrees. This activates one intake valve and one exhaust valve per cylinder via the valve star that is rotated 90 degrees, which enables variability of timing.

The crankcase and cylinder head have separate coolant circulation loops, each independently controlled. In the warm-up phase, for example, only a micro-circulation loop is active, which ensures quick warm-up of the engine block. Oil supply by the oil pump is regulated efficiently over two pressure levels. They are adapted to the engine’s demand for oil in its various load states and are switched according to demand.

The common rail system injects fuel at up to 2,000 bars of pressure via the 8-hole nozzles of the injectors. The higher pressure compared to the EU5 version results in even finer dispersion of the fuel in the combustion chambers, and this ensures efficient and low-emission combustion.

As in the 1.4 TFSI, the intercooler is integrated in the induction manifold – this solution enables short gas paths, good response, high control quality and good efficiency levels. The newly developed components for emissions control, DeNOx storage catalytic converter and diesel particulate filter, have been placed directly on the engine. Significantly shortened gas paths have improved emissions control response substantially. Also integrated in this subassembly is a low-pressure exhaust gas recirculation system; it reduces pressure losses to a minimum in exhaust gas recirculation.

The 1.6 TDI will follow somewhat later. The eight-cylinder engine produces 81 kW (110 hp) and 250 Nm (184.39 lb-ft) of torque. Another engine that will follow is the 2.0 TDI clean diesel in a version with 135 kW (184 hp) and 380 Nm (280.27 lb-ft) of torque.