September 7, 2004
Audi A4: Engine & Transmission
The new Audi A4: powerful yet economical petrol and TDI engines provide the basis for excellent performance. All engines are longitudinally installed and comply without exception with the limits of the EU4 emissions standard, regardless of transmission version.
Audi is now also offering two newly designed petrol engines with FSI petrol direct injection for the first time for the new A4: the 188 kW (255 bhp) 3.2 V6 and the turbocharged two-litre four-cylinder 2.0 T FSI, which delivers 147 kW (200 bhp). These combine high performance with a spontaneous response to every movement of the accelerator pedal and a peak-torque range at a high level.
The range also includes three engines which have been tried and tested several thousand times over: the two-litre inline four-cylinder unit, which develops 96 kW (130 bhp), and the 120 kW (163 bhp) 1.8 T four-cylinder version. The 75 kW (102 bhp) 1.6 completes the choice of petrol engines.
The TDI range at launch will include the 2.0-litre four-cylinder engine with pump-injector fuel injection and a power output of 103 kW (140 bhp), and the newly developed 3.0 TDI with common rail injection and piezo injectors.
What is currently the most modern TDI engine around made its debut a few months ago in the large A8 and A6 saloons. This immensely powerful V6 delivers 150 kW (204 bhp) in the A4 and makes 450 Nm of torque available between 1,400 and 3,200 rpm.
From the beginning of 2005, a coated diesel particulate filter, or catalysed soot filter as it is known, will be offered for the 2.0 TDI and 3.0 TDI models. This does not require an additive and therefore remains maintenance-free throughout the vehicle's entire service life. All 3.0 TDI versions will already be fitted with a filter provision from launch so that retrofitting can take place at Audi dealers at a later date with only very little work involved.
The engines deliver their power to the road either via the front wheels or by means of quattro permanent four-wheel drive. 5-speed or 6-speed manual gearboxes are available for the various A4 models, as is the continuously variable automatic transmission, the multitronic. This revolutionary Audi transmission technology will be available for the front-wheel-drive versions of the new A4. The now 6-speed tiptronic with sport program is offered as an option for quattro models.
The Petrol engines
3.2 V6 FSI
A new six-cylinder engine is being made available for the A4 for the very first time. The 3.2 V6 FSI, which only made its production debut in the new Audi A6 a few months ago, has all the features of an ultramodern petrol engine: FSI petrol direct injection with demand-controlled fuel supply, four valves per cylinder, a variable intake manifold and continuous camshaft adjustment on both the intake and the exhaust side.
This V6 engine delivers its maximum output of 188 kW (255 bhp) at 6,500 rpm. Its peak torque of 330 Nm is already available at 3,250 rpm. The A4 3.2 FSI with multitronic transmission and front-wheel drive accelerates from 0 to 100 km/h in 6.8 seconds and on up to a governed top speed of 250 km/h. This also applies to the version with quattro permanent four-wheel drive and 6-speed manual gearbox.
More than 90 percent of the engine's peak torque is available in the wide range between 1,900 and 5,900 rpm - a unique characteristic for a naturally aspirated V6. As far as the driver is concerned, this means a dynamic and forceful response to every movement of the accelerator pedal plus a broad usable speed range up to 7,200 rpm, hefty torque and excellent fuel efficiency: an average consumption of 9.3 litres of Super grade fuel per 100 km for the multitronic version is the best evidence of this engine's efficiency and the special abilities of FSI technology.
FSI engines develop more power and dynamism than conventional units with indirect fuel injection - and they do so with a very high standard of fuel economy. With the increase in efficiency achieved here, Audi has opened up a new dimension in the efficiency of standard spark-ignition engines and once again demonstrated the proverbial progress through technology familiar to the brand.
FSI direct petrol injection has confirmed its unique potential several times over in what must be the most challenging endurance test in the world: an engine with FSI direct injection powers the Le Mans-winning Audi R8.
How does the FSI technology differ operationally from a conventional engine? The term "petrol direct injection" makes the central feature clear: in contrast to indirect injection, the fuel is injected directly into the combustion chamber.
A common rail high-pressure injection system with a newly developed single-piston high-pressure pump operating on demand ensures exactly the right supply of fuel, delivering precisely the volume required for building up operating pressure between 30 and 110 bar.
In the intake tract, also comprising the two-stage variable intake manifold, moving charge-movement flaps provide the necessary tumble effect, swirling the induced air around depending on operating point. In order to achieve the high specific power and torque values, a new combustion process has been developed. This has the potential for worldwide application and for operation on the fuel grade RON 95/91. Together with the optimum geometry of the combustion chambers and the dosage of fuel injected with supreme accuracy down to the last millisecond, this allows a significant increase in compression:
While conventional production engines generally have a compression ratio of not more than 10.5:1, the compression ratio on Audi's 3.2 FSI power unit is 12.5:1 - a record on production cars and the essential prerequisite for the new engine's high standard of efficiency.
New Base Engine
Completely new in its design, the 3.2-litre V6 has been developed with the specific goal of maximum space efficiency: measuring only 360 millimetres in length and 430 millimetres in width, and weighing a mere 169.5 kg thanks to the use of aluminium, the engine offers significant benefits in terms of driving dynamics.
Like on Audi's new V-configuration engines in general, the cylinders are arranged at an angle of 90o and the distance between cylinders is 90 millimetres. Cylinder bore of 84.5 millimetres and cylinder lift of 92.8 mm add up to an overall engine capacity of 3,123 cc.
The four-valve cylinder head with a side opening for the injection valve is another special feature designed specifically for this 3.2-litre power unit. Both the inlet and exhaust camshafts come with variable adjustment to ensure optimum results, in terms of both maximum output and an extremely broad peak-torque range.
The camshafts, oil pump and balancing shaft are all driven by four-piece chain drive of the same type as in the 4.2-litre eight-cylinder unit.
Emissions control in the 3.2 FSI is optimised by two ceramic catalytic converters positioned close to the engine. As a result, this high-performance power unit easily undercuts the EU4 emissions standard.
Fine-tuning of the exhaust system offers the driver yet another bonus: the distinctly sporty but never irritating sound of a genuine six-cylinder unit, making the qualities of the engine a truly sensory experience.
The Audi A4 3.2 FSI with front-wheel drive is available with the continuously variable multitronic transmission. On the model with permanent quattro four-wheel drive, a 6-speed manual gearbox is responsible for regulating torque and power. The 6-speed tiptronic with sport program is also offered as an alternative for quattro models.
The 2.0 T FSI
The 2.0 T FSI, an entirely newly developed engine, is also making its first appearance in the range of petrol engines for the new Audi A4. This is the first time in this class that turbocharging has been combined with the FSI concept of petrol direct injection.
The term "petrol direct injection" makes the distinction between this and conventional petrol engines clear: in contrast to indirect injection, the fuel is injected directly into the combustion chamber.
The injector, located on the admission side in the cylinder head, is served by a high-pressure pump driven by the camshaft and a pressure reservoir shared by all cylinders - the common rail system. The injector regulates fuel delivery with millisecond precision, at injection pressures of up to 110 bar.
The engine block is made from GG 25 grey cast iron, a material that exhibits both high pressure resistance and excellent acoustic properties.
A mass balance transmission further improves the acoustics. Two balancing shafts rotating at double the speed of the crankshaft compensate for the engine's inertial forces. The power is transmitted by the crankshaft by means of a triangular-layout chain which drives the oil pump as well as the balancing shafts.
The outcome of these measures is outstanding vibrational properties for a four-cylinder engine. Perceptible vibrations and irritating humming frequencies are both effectively suppressed. The pleasing sound of the specially tuned exhaust system aptly complements these properties.
The intake manifold on the 2.0 T FSI is made from a high-tech plastic. It also integrates the charge movement flaps, the position of which is adjusted by a continuous-action pilot motor. The optimum movement of the airflow, or tumble, can thus be controlled on the basis of the engine-speed and load conditions.
The fuel is injected via a common rail system supplied by a demand-controlled high-pressure pump. The fuel is injected directly into the combustion chamber via an injector positioned at one side between the inlet valves.
The fuel-air mixture is distributed purely homogeneously within the combustion chamber. This provides a distinctive characteristic, placing the emphasis on high performance and agile responsiveness at all engine speeds.
The four-valve cylinder head with low-friction roller cam follower drive has a modified inlet duct geometry that produces even higher tumble values than the naturally-aspirated FSI engine. This results not only in greater refinement, but also in superior knock resistance and therefore efficiency.
As a result, the turbo engine achieves a compression ratio of 10.5:1, a figure that is otherwise achieved only by modern naturally-aspirated engines. This, coupled with the advantages of petrol direct injection, plays a crucial role in boosting the thermodynamic efficiency compared with both manifold injection engines and conventional turbo engines.
The maximum torque of 280 Nm is available from just 1,800 all the way up to 5,000 rpm. This exceptionally broad torque plateau on the one hand permits a fuel-efficient driving style with few gearshifts, and on the other hand means that only light accelerator action is needed to produce assertive thrust and a spontaneous unleashing of power.
This technology lends the A4 2.0 T FSI flexibility values that are on a par with much larger-capacity sports cars: in 4th gear, the mid-range spurt from 80 to 120 km/h that is typically required for overtaking manoeuvres takes just 6.9 seconds.
It is moreover impressive how spontaneously the new turbo engine always responds to accelerator action, and how assertively it translates pedal movement into acceleration.
The A4 2.0 T FSI with 6-speed manual gearbox accomplishes the classic 0100 km/h sprint in only 7.3 seconds; its powerful 147 kW (200 bhp) engine is capable of taking it up to an impressive top speed of 241 km/h.
The inline four-cylinder engine with a displacement of 1,984 cc and an output of 96 kW (130 bhp) is a bestseller that has been built since 2000.
The engine block of the two-litre engine is made of aluminium for significantly reduced weight. At 129 kilograms, Audi's two-litre four-cylinder engine is the lightest in its class, and with a length of a mere 460 millimetres it is also the most compact.
As an undersquare engine, the two-litre unit is ideal for a good torque characteristic at the low end of the speed range. To make maximum use of this potential, there is map-controlled adjustment of the inlet camshaft through 42 degrees. A pivoting motor controlled by the engine management system maintains the necessary pressure in the hydraulic system. A highly wear-resistant toothed belt transmits the power.
A two-stage variable intake manifold governs the desired power output and torque characteristic. The 2.0-litre unit reaches its maximum torque of 195 Nm at 3,300 rpm; 90 percent of this maximum value is available across the broad speed range of 2,300 to 5,000 rpm.
This engine achieves its maximum power output of 96 kW (130 bhp) at 5,700 rpm. It propels the A4 saloon with front-wheel drive and 5-speed manual gearbox to 100 km/h in 9.9 seconds, and on to a top speed of 212 km/h. And considering this model consumes an average of only 8.0 litres of fuel per 100 km, these figures certainly are impressive
The task of exhaust emission control is performed by a multi-stage catalytic converter located close to the engine. This achieves its full output very soon after the engine is started thanks to the extra-short heating-up times. This rapid light-off is supported by the design of the new exhaust manifold on the 2.0-litre engine.
The fact that the 2.0 5V easily complies with EU4 exhaust emission requirements can almost be taken for granted.
The 1.8 T
An engine version that has likewise been tried and tested several thousand times over will also be included in the range when the new Audi A4 is launched: the 1.8 T four-cylinder turbo which delivers 120 kW (163 bhp). It is an outstanding example of how a modern supercharged engine can combine high power output with refinement. The 1.8 T is solid proof that sometimes there is a genuine alternative to sheer size.
Instead of priming its small, very responsive exhaust turbocharger for a peak output value, Audi has placed the emphasis on achieving a substantial, ideally accessible torque curve across a wide range.
It encourages the driver to move up the gears earlier on, so that a more economical higher gear can be used more frequently and for longer periods. All this is fully compatible with ample driving enjoyment.
Peak torque of 225 Nm is reached at a speed of just 1,950 rpm. This hefty torque remains constant up to 4,700 rpm. This means that maximum torque is always available in the predominantly used driving/engine-speed range.
The A4 1.8 T with front-wheel drive and manual gearbox consumes just 8.2 litres of unleaded Super petrol per 100 km. The saloon's power output of 163 bhp accelerates it from 0-100 km/h in just 8.6 seconds and propels it on up to a top speed of 228 km/h.
Plenty of know-how has gone into this, the current entry-level 1.6-litre engine for the A4. A cylinder head with valve actuation by roller cam followers reduces interior friction considerably.
Together with the engine electronics and an optimised exhaust system, these measures have resulted in the exceptionally low fuel consumption of just 7.7 litres.
The engine's power output of 75 kW (102 bhp) and its torque of 148 Nm accelerate the A4 1.6 saloon to a maximum speed of 190 km/h.
This version completes the sprint from 0 to 100 km/h in 12.6 seconds. And like the other engines, this version also fulfils the strict limits of the EU4 standard.
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