Drivetrain

Audi is initially offering the new A3 Sportback with a choice of two TDI and two TFSI engines, all of which are new developments. Their engine displacements range from 1.4 to 2.0 liters and their power from 77 kW (105 hp) to 132 kW (180 hp). Additional diesel and gasoline engines will follow somewhat later, as will the TCNG engine, which can be operated on Audi e-gas or natural gas. The bivalent TCNG engine can be operated on gasoline, natural gas or Audi e-gas. All of the engines follow the Audi engine philosophy of downsizing, in which displacement is replaced by forced induction for strong performance and low fuel consumption. Fuel consumption has been reduced on average by around nine percent compared with the previous model.

Technologies from the Audi modular efficiency platform play a key role in the reductions achieved in fuel consumption. That start-stop system uses powerful fleece, AGM or EFB batteries and reduces fuel consumption by roughly 0.3 liters per 100 km.

The innovative thermal management system (in the 1.8 TFSI and the TDI engines) ensures that the engine comes up to its operating temperature rapidly after a cold start. This shortens the phase of elevated friction losses due to viscous oil, and the car’s interior warms up faster as well.

All engines have the same mounting position in the new Audi A3 Sportback – a result of standardization based on the Group’s modular transverse matrix. In the previous model, the gasoline engines in some cases were still installed inclined 10 degrees to the front. Their exhaust side faced the radiator, whereas that of the TDI engines faced to the rear, i.e. toward the cabin. In the new Audi A3 Sportback, all gasoline engines have their exhaust side facing the rear, and – like the diesel engines – they are also tilted 12 degrees towards the rear.

This mounting arrangement and the compact layout of the new gasoline engines shorten the installation length in front by about 50 mm (1.97 inches) compared with the previous model. This let the Audi developers shift the front axle forward by 40 mm (1.57 inches). The front overhang was shortened by the same amount, which benefits crash behavior, styling and the distribution of axle loads.

Audi A3 Sportback: TDI engines

The TDI engines from Audi have been setting standards for decades. They stand for a contemporary, smart type of sportiness – exhibiting a harmonious blend of supreme power, high torque, impressive efficiency and smooth running properties.

1.6 TDI
The 1.6 TDI is the most efficient engine in the Audi model lineup. The compact diesel engine, which displaces 1,598 cc (bore x stroke 79.5 x 80.5 millimeters [3.13 x 3.17 in]) impresses with the systematic minimization of internal friction. Improvements were achieved through the integration of thermal management measures in the oil and coolant loops, the choice of materials for the piston rings and the piston pin, and in the manufacturing process through the use of a special honing process for the crankcase cylinder barrels.

The solenoid injectors of the common rail system can perform six separate injection operations per work cycle, which benefits combustion and exhaust quality as well as engine smoothness. A new feature is the intake manifold-integrated charge air intercooler for diesel engines. This results in an extremely compact charge air path, which improves engine responsiveness substantially. An exhaust turbocharger with adjustable turbine geometry and the unthrottled intake and charging air system round out the overall concept.

In combination with the manual transmission, the 1.6-liter TDI accelerates the Audi A3 Sportback from zero to 100 km/h (62.14 mph) in 10.9 seconds on its way to a top speed of 195 km/h (121.17 mph). The diesel engine consumes on average just 3.8 liters of fuel per 100 km (61.90 US mpg), corresponding to 99 grams of CO₂ per km (159.33 g/mile).

2.0 TDI
Two versions of the newly developed 2.0 TDI are available for the new Audi A3 Sportback. Performance figures for the version with 100 kW (150 hp) and 320 Nm (236.02 lb-ft) are: 8.7 seconds for the sprint from zero to 100 km/h (62.14 mph) and a top speed of 216 km/h (134.22 mph). Average fuel consumption is just 4.2 liters per 100 km (56.00 US mpg), corresponding to CO₂ emissions of 108 grams per kilometer (173.81 g/mile).

The more powerful version of the 2.0 TDI to follow somewhat later offers 135 kW (184 hp) and 380 Nm (280.27 lb-ft) of torque. The key data (with manual transmission and front-wheel drive): zero to 100 km/h (62.14 mph) in 7.4 seconds, top speed of 232 km/h (144.16 mph), average fuel consumption of 4.4 liters per 100 km (53.46 US mpg) and 114 grams CO₂ per km (183.47 g/mile).

The 2.0 TDI with its 1,968 cc of displacement (bore x stroke 81.0 x 95.5 mm (3.19 x 3.76 in)) was systematically designed for low friction losses. The toothed belt in the oil pan drives the oil and vacuum pumps, which are located in a housing, via the crankcase. The two balance shafts, which were moved from the oil pan to the crankcase, are mounted on roller bearings and serve to balance the free mass forces.

Elaborate needle bearings are used in the drive system for the camshafts as well. The assembled shafts are mounted in a separate frame and mated directly in this modular component. The new valve train module is characterized by high stiffness and low weight. In contrast to the previous engine, the cylinder head has a rotated valve star layout; each of the two camshafts actuates one intake valve and one exhaust valve per cylinder.

At the pistons, reduced stress on the rings results in smooth running; in manufacturing the engine, a honing process in fine machining of the cylinder liners guarantees high precision. The oil pump, with its two-stage control, requires very little drive energy. The cylinder block and cylinder head each have separate coolant circulation loops. The pump for block circulation can be deactivated during the warm-up phase, so that only the cylinder head circulation loop is active.

The common rail injection system develops up to 1,800 bar of system pressure, which will increase to 2,000 bar in the version with 135 kW (184 hp) to follow later. The fuel is nebulized via eight-port nozzles. The turbocharger operates with adjustable guide vanes whose pneumatic activation has been further refined. The intercooler is integrated into the induction pipe – this type of construction leads to short gas paths, high control quality and very good engine efficiencies. The new low-pressure exhaust gas recirculation system is also very compact and is configured for low flow losses. The emissions control system was located near the engine and is already prepped for the future Euro 6 emissions standard.

Audi A3 Sportback: TFSI engines 

The abbreviation TFSI represents the combination of gasoline direct injection and turbocharging, a technology that Audi was the first carmaker in the world to introduce. The combination of the two technologies results in high power and high torque as well as low fuel consumption.

1.2 TFSI
The entry-level gasoline engine is the completely new 1.2 TFSI, which will join the engine lineup for the new Audi A3 Sportback somewhat later. The unit exemplifies the philosophy of downsizing and has been designed for low weight. The engine weighs just 99.6 kilograms (219.58 lb) without add-on parts. The 1.2 TFSI has four valves per cylinder and displaces 1.197 cc (bore x stroke 71 x 75.6 millimeters [2.80 x 2.98 in]). The piston rings with their low pretension and compact main and connecting rod bearings of the crank shaft are optimized for low friction.

The aluminum crankcase has its own coolant circuit separate from the cylinder head. A regulated water pump ensures that the water in the block is not circulated immediately after the engine is started, enabling the engine to come up to temperature more quickly. The common rail unit injects the fuel at up to 150 bar pressure into the combustion chambers. The turbocharger has an electric actuator that actuates the wastegate flap particularly quickly and precisely. Boost pressure develops spontaneously and fuel consumption under partial load decreases.

The 1.2 TFSI produces 77 kW (105 hp) and 175 Nm (129.07 lb-ft) of torque. It accelerates the A3 Sportback from zero to 100 km/h (62.14 mph) in 10.5 seconds. Top speed is 193 km/h (119.92 mph).

With the manual transmission, average fuel consumption is just 4.9 liters per 100 km (48.00 US mpg), corresponding to CO₂ emissions of 114 grams per km (183.47 g/mile).

1.4 TFSI
The 1.4 TFSI with 1,395 cc engine displacement (bore x stroke: 74.5 x 80.0 mm [2.93 x 3.15 in]) is an engine that is new from the ground up. Its crankcase is made of die cast aluminum instead of the grey cast iron of the previous engine. It only weighs 18 kg (39.68 lb) instead of 33 kg (72.75 lb). Other changes, e.g. to the crankshaft and the connecting rods, contribute towards the new 1.4 TFSI attaining a weight of only 107 kg (235.89 lb). The 21 kg (46.30 lb) reduction also yields significant benefits in terms of axle load distribution.

Another innovation is integration of the exhaust manifold in the cylinder head. It quickly brings the coolant to temperature after a cold start; only then does a thermostat in the new coolant pump module enable cooling of the crankcase. At full load – e.g. during very fast freeway driving – the cooling jacket reduces the temperature of the exhaust gases. This eliminates the process of enriching the fuel-air mixture which would otherwise be necessary – which improves fuel economy significantly.

The aluminum pistons were redesigned; the nearly flat design of the piston heads is precisely tuned to the intake ports that were also redesigned. The common rail system operates at pressures of up to 200 bar, and its five-hole injectors can deliver up to three injections per operating cycle.

The turbocharger has shed 1.8 kg (3.97 lb) of weight compared with the previous engine. Its newly developed electric wastegate adjuster operates very quickly and precisely, which significantly improves engine responsiveness. The intercooler, which is also integrated in the induction pipe, accelerates the buildup of charge pressure – in a way similar to the 2.0 TDI.

In the 1.4 TFSI, friction losses were reduced by up to 20 percent compared to the previous engine. Improvements were made to the piston rings and their play when mounted in the grey cast iron cylinder sleeves, their reduced diameter at the crankshaft main bearing, lighter-weight valves and toothed belts for the timing and ancillary drives designed to last the life of the engine. The pressure-regulated oil pump also contributes to efficiency.

Like the 2.0 TDI, the 1.4 TFSI has a valve train module with low-friction camshaft bearings – with the difference that the shafts are integrated directly in the valve cover. The intake camshaft can be adjusted over 50 degrees of crank angle.

The new 1.4 TFSI produces 90 kW (122 hp) and 200 Nm (147.51 lb-ft) of torque, accelerating the A3 Sportback from zero to 100 km/h (62.14 mph) in 9.5 seconds on its way to a top speed of 203 km/h (126.14 mph). Its average fuel consumption is 5.3 liters of fuel per 100 km (44.38 US mpg), which corresponds to 123 grams of CO₂/km (197.95 g/mile).

A second version of the 1.4 TFSI to follow somewhat later produces 103 kW (140 hp) and 250 Nm (184.39 lb-ft) of torque. It features the innovative cylinder on demand (COD) system, which deactivates the second and third cylinders at low to intermediate loads and while coasting. The powerful 1.4-liter engine’s average fuel consumption is thus 4.7 liters of fuel per 100 km (50.05 US mpg); CO₂ emissions with the S tronic are just 110 grams per km (177.03 g/mile). Performance is strong, with a time of 8.4 seconds for the standard sprint and a top speed of 213 km/h (132.35 mph).

1.4 TCNG
A TCNG engine with 81 kW (110 hp) is making its debut in the new Audi A3 Sportback. It has been systematically designed for operation on Audi e-gas. It consumes just 3.6 kilograms of natural gas or Audi e-gas, which Audi produces itself in a sustainable manner, per 100 km (65.34 US mpg). With either fuel, CO₂ tailpipe emissions are less than 100 grams per km (160.93 g/mile).

The greenhouse gas balance is even more attractive in a well-to-wheel analysis that accounts for all factors from the fuel source to the car’s wheels. When the A3 Sportback TCNG is powered by Audi e-gas, no more CO₂ is released than was chemically input in its production beforehand – creating a closed loop. Even if the energy required to build the e-gas facility and wind turbines is included in a comprehensive analysis, CO₂ emissions are still less than 30 grams per km (48.28 g/mile) in the overall energy balance

The engine is based on the newly developed 1.4 TFSI. Key modifications relate to the cylinder head and turbocharging; the injection system and catalytic converter are specially configured for natural gas operation as well. The 1.4 TCNG is bivalent, which means that despite the optimization of the engine for operation on natural gas, it outputs the same power and torque when operated on gasoline. When the pressure in the gas tank drops below a certain limit, the engine management system automatically switches to gasoline mode.

The Audi A3 Sportback TCNG has a range of over 400 km (248.55 miles) when operated on natural gas, and can cover an additional 780 km (484.67 miles) on gasoline if necessary. This adds up to a total driving range equivalent to that of an Audi A3 Sportback TDI. Two indicators in the instrument cluster inform the driver of fuel tank levels at a glance. The filler necks are placed under a common fuel door.

As part of the Audi e-gas project, the brand with the four rings is the world’s first car manufacturer to establish an entire chain of sustainable energy carriers. Its end products are hydrogen and the synthetic Audi e-gas. The Audi e-gas facility that is currently being built in Werlte in the Emsland region will be operated with renewable electricity (e.g. from wind energy and solar energy).

1.8 TFSI
The new 1.8 TFSI – the most powerful engine in the new A3 Sportback at market launch – showcases Audi’s high-tech competence with innovative solutions in many technical areas. Its torque curve is like that of a TDI – its maximum torque of 250 Nm (184.39 lb-ft) is already available at 1,250 rpm, and it remains constant up to 5,000 rpm. Its power is 132 kW (180 hp).

A major innovation in the 1.8 TFSI is the addition of indirect injection. Complementing FSI direct fuel injection, it is active at part load; it injects the fuel at the end of the induction pipe in the vicinity of the tumble flaps, where it is intensively tumbled with the air.

The resulting improved mixture formation boosts fuel economy and reduces particulate emissions. Direct FSI fuel injection, with its up to 200 bar pressure, comes into play in the starting phase and at higher loads.

Audi engineers have discovered new degrees of freedom in filling the combustion chambers. The intake and exhaust camshafts are adjustable; on the exhaust side, the Audi valvelift system also varies the strokes of the valves to further minimize charge changing losses.

The innovative thermal management system is controlled by two rotary valves, which are combined in a module and driven by an electric motor via a worm gear. They ensure that the engine oil is rapidly heated, and they regulate coolant temperature between 85 and 107 degrees Celsius according to the driving situation. At all loads and engine speeds they strike an optimal balance between minimal friction and high thermodynamic efficiency.

As in the 1.2 TFSI and 1.4 TFSI, the exhaust manifold of the 1.8 TFSI is integrated in the cylinder head where coolant is circulating. This solution reduces the temperature of the exhaust gases, which improves fuel economy at full load. The turbocharger is also a new development; it builds up its high relative charge pressure of up to 0.8 bar very dynamically. Its main features are an electric wastegate adjuster, which regulates the charge pressure rapidly and precisely, and a turbine wheel made of a new alloy that can handle exhaust gases as hot as 980 degrees Celsius.

Despite all of its new technologies, the 1.8 TFSI only weighs a little over 140 kg (308.65 lb) – a value that is attained by such measures as reducing wall thickness slightly in the grey cast iron crankcase compared with the previous model. The walls are only about three millimeters (0.12 inch) thick, saving about 2.4 kg (5.29 lb). The pistons consist of a new high-strength alloy. The oil pan consists of a lightweight plastic, and many screws in the engine are aluminum.

Internal friction is low as well – due to a new type of coating for the piston skirts, low-friction bearings for the two balancer shafts and a reduced-diameter main bearing for the crankshaft that is 1.6 kg (3.53 lb) lighter and only requires four counterweights. The regulated oil pump requires little energy itself, and a high-precision electric system controls the piston heads with jets of oil.

Key performance data of the 1.8 TFSI with S tronic and front-wheel drive: from zero to 100 km/h (62.14 mph) in 7.3 seconds, top speed of 232 km/h (144.16 mph) and average fuel consumption of 5.6 liters per 100 km (42.00 US mpg) corresponding to 130 grams CO₂ per km (209.21 g/mile).

Future engines
Audi will quickly expand the range of engines for the A3 Sportback. It includes a dynamic S model and additional high-efficiency, low-emissions variants. The Audi A3 Sportback e-tron with a powerful plug-in hybrid drive will follow in 2014.

Power transmission
At market launch of the new A3 Sportback, Audi is pairing the 1.4 TFSI and the 2.0 TDI with a manual six-speed transmission. It shifts easily and precisely over short paths and is distinguished by high efficiency. As in all Audi transmissions, the gear spread is large – the lower gears have relatively short gear ratios, while the last gear is comparatively long to reduce engine revs. The S tronic is available as an option with all engines. Depending on the version, the dual-clutch transmissions shifts extremely quickly and nearly imperceptibly through six or seven gears.

The new Audi A3 Sportback 1.8 TFSI comes standard with a seven-speed S tronic; it unites the comfort of a classic automatic with the dynamic performance and efficiency of a manual transmission. The driver can operate the S tronic via the selector lever or with the optional paddles on the steering wheel. Shift points are somewhat higher in the automatic S mode, whereas D mode prioritizes taller gear ratios. When combined with the Audi drive select dynamics system (standard in Ambition), the S tronic includes a free-wheeling function in efficiency mode that further reduces fuel consumption.

The seven-speed S tronic consists of two sub-units; two multi-plate clutches service the gears. The large K1 clutch located on the outside directs the torque via a solid shaft to the gear wheels for the gears 1, 3, 5 and 7. It is connected to the smaller K2 clutch, which is integrated inside its larger sibling, and which acts on the gear wheels for gears 2, 4 and 6, as well as reverse.

Both transmission structures are continuously active, but only one of them is connected to the engine at any one time. For example, when the driver accelerates in third gear, the fourth gear is already engaged in the second transmission section. Shifts are performed by switching the clutches. This takes just a few hundredths of a second and happens without any noticeable interruption in propulsive power.

The seven-speed S tronic, which is about 37 cm (14.57 inches) long, is very compact and only weighs about 70 kg (154.32 lb). The two clutch mechanisms do not require an oil supply, which further boosts their already impressive efficiency. A regulated electric oil pump supplies the clutch and gear actuators.

quattro permanent all-wheel drive
The manual six-speed transmission and the seven-speed S tronic send the power to the front wheels of the new A3 Sportback. Audi will offer the A3 Sportback somewhat later with optional quattro permanent all-wheel drive, which uses a newly developed multi-plate clutch. The hydraulically actuated and electronically controlled component, which can send the power from the front to the rear axle in just a few milliseconds, weighs significantly less than the previous unit.

In the interest of better axle load distribution, the clutch is located on the end of the prop shaft, in front of the rear differential. Inside is a package of plates that rotate in an oil bath. The metal friction rings are arranged behind one another in pairs – one ring of each pair is rigidly meshed with the housing, which rotates with the prop shaft; the other ring is meshed with the output shaft to the rear axle differential.

During normal driving, the clutch sends most of the engine’s power to the front wheels. If traction decreases there, the clutch can variably transfer torque to the rear axle within a few milliseconds by pressing the sets of plates together under control. A pressure reservoir helps the electric reciprocating piston pump to develop the necessary oil pressure, which can reach over 100 bar.

The equipment and data specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.