The new Audi TT Coupé is available from launch with a choice of two transverse petrol engines one a four-cylinder turbo, and the other a naturally aspirated V6. Both power units provide it with impressive pulling power and top performance. Their output enables the lightweight coupe to perform impressively on the road.
The 2.0 TFSI
The direct-injection four-cylinder turbo engine that goes under the abbreviation TFSI has a displacement of 1,984 cm3. An international jury of experts voted it "Engine of the Year" for two years in succession, in 2005 and 2006, thus paying fitting tribute to its innovative technological package. The TFSI combines FSI petrol direct injection, which Audi developed, with exhaust turbocharging an ideal alliance.
An FSI engine makes better use of the fuel than a conventional engine with indirect manifold injection: it delivers more power and dynamism. Its fuel consumption at frequently encountered part loads is lower. This superior efficiency demonstrates once again what Audi means by its "Vorsprung durch Technik" slogan. Audi's petrol direct injection concept first supplied compelling evidence of its superior potential in June 2001, when an FSI engine took the sports prototype to a resounding overall victory in the Le Mans 24 Hours. Numerous other wins followed over the next four years.
In FSI technology the fuel is injected from a high-pressure accumulator at intervals of every few milliseconds at a pressure of between 30 and 110 bar, directly into the combustion chambers.
There are flaps located in the intake tract operated by actuating motors, directly in front of the intake valves.
The flaps induce a rolling type of movement in the incoming air. The injectors atomise the fuel into this "tumble" inside the combustion chambers, at a cone of about 70 degrees.
During direct injection, as the fuel evaporates it extracts heat from the combustion chambers. This effect was used by the development engineers to overcome the fundamental problem faced by all turbocharged engines the high amount of heat generated, and the engine's resulting tendency to knock, necessitating a reduced compression ratio. For the TFSI, Audi has been able to achieve a compression ratio of 10.3:1, a figure hitherto achieved only by naturally aspirated engines. This significantly improved the engine's thermodynamic efficiency.
The continuously variable intake camshaft contributes towards optimum cylinder filling across the entire engine-speed range; the valves are actuated by low-friction roller cam followers. The pistons are made from a highly heat-resistant aluminium alloy with a cast-iron reinforced piston-ring carrier zone they are particularly light in weight and are designed for a combustion pressure of up to 125 bar. Two balancing shafts rotating at double the speed of the crankshaft compensate for the second-degree inertial forces and also achieve a high standard of acoustic comfort.
The turbocharger's charge-air cooler is installed immediately ahead of the engine cooler in a thermally ideal position in which it also catches the airflow of the electric cooling fan. Cooling of the compressed air increases the charging efficiency of the cylinders. Crucial details of the charger have been revised its optimised turbine wheel, for instance, results in a higher degree of efficiency and a superior response. The turbine housing is made from a single grey cast iron component, together with the exhaust manifold.
280 Nm: the two-litre engine is a torque supremo
The TFSI performs all the tasks that it is presented with adeptly and confidently. The undersquare four-valve engine runs with refinement, responds spontaneously to the throttle and revs up effortlessly. Its constantly high propulsive power ranks as its most notable virtue. The two-litre engine puts 280 Nm of torque onto the crankshaft even at engine speeds as low as 1,800 rpm, and is able to keep this high level of torque constant up to 5,000 rpm. The nominal power output of 147 kW (200 bhp) is delivered between 5,100 and 6,000 rpm. The 2.0 TFSI accelerates the Audi TT to 100 km/h in just 6.4 seconds (in the version featuring the S tronic dual-clutch gearbox) and on to a top speed of 240 km/h. It clocks up 100 kilometres on an average of 7.7 litres of premium-grade fuel, irrespective of transmission type.
The 3.2 V6
Even more power is on tap from the V6 engine with its 3,189 cm3 capacity. It achieves a peak torque of 320 Nm at engine speeds as low as 2,500 to 3,000 rpm, and an output of 184 kW (250 bhp) at 6,300 rpm. Many aspects of it have been revised compared with the version in the previous TT model. The reconfigured mapped characteristic ensures that the engine responds to the throttle even more spontaneously and with more "bite" in all engine speed ranges.
On the road, the 3.2-litre unit reveals itself to be high-torque and high-revving. It produces a fascinatingly sonorous response that also accentuates the intake sound at all engine speeds, whereas the sound produced by the four-cylinder version is primarily based on the exhaust spectrum. The TT 3.2 quattro with the six-speed gearbox sprints from a standing start to 100 km/h in 5.7 seconds (with S tronic). Its top speed is 250 km/h (governed). Average fuel consumption is 9.4 litres per 100 km (with S tronic).
The V6 is suitable for installation transversely to the direction of travel. This has been made possible by its extremely narrow included angle of 15 degrees between the cylinder banks; both banks share the same cylinder head.
Both camshafts can be adjusted continuously, for more effective cylinder filling by 52 degrees at the intake end and 42 degrees at the exhaust end. The engine is fitted with a variable intake manifold for the same purpose.
Both engines in the new Audi TT Coupé can be equipped with two transmission variants. The standard spec is a six-speed manual gearbox in a lightweight magnesium casing.
One dynamic highlight that gives the TT a unique status within the competitive field is the optional S tronic, which combines the advantages of an automatic transmission with those of a manual gearbox. Thanks to innovative dual-clutch technology, the transmission can change its six gears in a breathtaking 0.2 of a second, without interrupting the power flow. The TT driver benefits from fascinating agility and ultra-convenient gear changing in equal measure.
The S tronic is basically two three-speed transmissions, each with their own clutch, accommodated in a single housing. The two multi-plate clutches are located up against each other. The first one serves the odd-numbered gears and reverse, and the second one serves the even-numbered gears. Two input shafts sharing the same axle are connected up to them, with a solid shaft running inside a hollow shaft.
When the TT is being driven in third gear, for instance, the second clutch is disengaged. As the transmission computer assumes that a driver who is accelerating is about to change to fourth gear, it already engages that pair of gears in anticipation. As soon as the shift command is given, the first clutch is disengaged and the second clutch is engaged almost simultaneously. This process takes just a few hundredths of a second and is performed without the need for the driver to release the accelerator and without any noticeable interruption to the power flow, but very smoothly.
Always well informed: networked control
Every transmission speed is assigned a conventional switching unit, as a result of which it is for instance also possible to change directly from sixth to second gear. This function is controlled by an electro-hydraulic device; the computer that is responsible for it is networked with the engine and suspension management, which supplies all the key information it needs to operate. The electronically controlled throttle blip in the manual and S modes reinforces the impression of ultra-dynamic gearshifts.
The S tronic can be operated by means of the one-touch lever or, in motor racing style, manually by the shift paddles on the steering wheel. There are furthermore two fully automatic operating principles available, N for Normal and S for Sport. The S program is configured for later shift points, earlier downshifts and shorter shifting times. Even in the two automatic modes, it is possible to switch temporarily to the manual plane via a one-touch function.
The oilbath-running multi-plate clutches that the S tronic uses can realise various starting characteristics ranging from a gentle start on a slippery surface to sporty acceleration under full load. Another dynamic feature in the TT is the launch control a start program delivering optimum acceleration from standstill for the TT.
The Audi TT with the four-cylinder TFSI is fundamentally a front-wheel-drive model, whereas the V6 features permanent four-wheel drive. Its quattro drive system, developed specially for transverse-mounted engines, operates with an electronically controlled and hydraulically actuated multi-plate clutch. In order to improve the distribution of axle loads, the clutch is positioned to the rear of the TT, at the end of the propshaft in front of the rear axle differential.
The package of plates, which runs in an oilbath, can be compressed under a controlled pressure potentially as high as 100 bar the greater the pressure, the higher the drive torque that the clutch can transmit to the rear axle.
The structure, comprising a separate oil supply and two axial-piston pumps, permits a pressure buildup with lightning speed. In normal driving conditions, the clutch directs 85 percent of the torque to the front wheels, but in extreme circumstances it is able to transmit as much as 100 percent of the forces continuously to one of the two axles.
Compared with the unit in the predecessor model, the service intervals for the quattro drive have been doubled to 60,000 kilometres. The mechanical construction and the precision of the control function have likewise been further enhanced, and the mapped characteristics given sporty settings. The clutch's control unit evaluates a large variety of data, including wheel and engine speed, road speed and engine torque. It also identifies the driving situation and the driver's intentions, and takes them into account in its control strategy.
This adaptive distribution of torque enables the quattro drive system to achieve particularly high traction and outstanding acceleration. It also provides ample reserves for the transmission of cornering forces assuring TT drivers optimum safety and lots of driving fun whatever the conditions. The competitors in this segment have no comparable solutions to offer.
The latest generation of the TT demonstrates even greater levels of dynamism and agility than its predecessor. On the North Loop of the Nόrburgring, the toughest test track in the world, the new TT Coupé knocks 15 seconds off the time its predecessor achieved a truly substantial difference. The main reason, apart from the fact that its centre of gravity has been lowered by nine millimetres to 311 millimetres, is its elaborate new chassis.
The aim was to achieve a neutral to mildly understeering self-steering behaviour right up to the limits of handling. The measures that the developers implemented affected all components and assemblies, ranging from the wider track, through larger tyres and redefined elastokinematics, to the completely re-engineered rear axle. The progress that they achieved really can be felt particularly compared with the chassis of the first generation, which the trade press already rated very highly.
The front suspension
The front suspension, with a track of 1,572 millimetres an increase of 44 mm features a design principle that had already proved highly effective in the new TT's predecessor, a McPherson structure with triangular lower wishbones. The pivot bearings, the subframe and the wishbones are now made from aluminium, significantly reducing the unsprung weight by 2.5 kilograms for the transverse links alone.
The subframe is bolted rigidly to the body, thus imparting the forward structure with exceptionally high rigidity. New linear pistons in the shock absorbers permit an even finer balance between dynamism and comfort. The instantaneous centre was raised by 22 millimetres to 64 millimetres, as a result of which the degree to which the body tilts sideways is less pronounced, appreciably benefiting a sporty driving style.
The direct-ratio electromechanical rack-and-pinion steering, the servo assistance of which is governed as a function of road speed, is new on the Audi TT. It combines precise, firm steering feedback with minimal sensitivity to excitation from the road surface, and operates on far less energy. Because the electromechanical system only cuts in when it is needed, it saves on average 0.2 litres of fuel per 100 kilometres, depending on driving conditions.
The rear suspension
One crucial area of progress compared with the torsion-beam rear axle concept of the first generation is the four-link rear suspension on both the quattro and the front-wheel-drive versions. The track measures 1,558 millimetres, an increase of 45 mm on the previous model. Apart from the subframe, which is made from aluminium instead of sheet steel and accommodates the extra differential, the design on the 3.2 quattro does not differ appreciably from the front-wheel-drive version, and the luggage compartment capacity is identical on both versions.
The four-link principle used on the TT combines a compact design with low weight and, above all, superior handling. Its particular strengths stem from the functional separation of longitudinal and transverse forces.
The longitudinal links absorb the driveline and braking forces, and their relatively soft mounts provide outstanding ride comfort. On the other hand, the three wishbones per wheel the spring link, the upper wishbone and the tie rod are attached very rigidly to the subframe, for optimum handling characteristics. As on the front axle, the subframe is bolted firmly to the body, lending the rearward structure additional rigidity.
Numerous lightweight-design components help to reduce the unsprung weight effectively; all control arms, for instance, are made from high-strength grades of steel. Separate springs and shock absorbers provide the necessary vertical support. The twin-tube gas-filled shock absorbers are located close to the wheels, thus maximising the width of the luggage compartment.
In summary, all these individual features add up to a very sporty concept. The new TT obeys steering movements with exemplary precision and spontaneity, and its body movements are kept to the bare minimum. The self-steering behaviour is neutral right up to a very high handling limit, which signals itself to the driver through slight understeering. The elaborately configured elastokinematics specifically of the rear axle assure this.
In the version with the steel chassis, the suspension of the new TT Coupé is firm but in no way uncomfortable it yields sensitively and discreetly senses the road surface's properties.
Wheels and brakes
Compared with its predecessor model, the wheels of the new Audi TT have become larger. The TT Coupé 2.0 TFSI features 16-inch cast aluminium wheels, fitted with 225/55 R 16 tyres. The 3.2 quattro features forged 17-inch lightweight alloy wheels, fitted with 245/45 R 17 tyres. For drivers who prefer an out-and-out sports style, there are three designs of 18-inch wheels with 245/40 R18 tyres to choose from. quattro GmbH can in addition supply wheels of up to 19 inches in diameter for the Audi TT, with size 255/35 R 19 tyres.
All 17-inch and 18-inch wheels come with tyres with reinforced sidewalls. Run-flat tyres of this kind are able to continue for 50 km after suffering a total loss of pressure at a vehicle speed of 80 km/h, without the driver noticing any significant deterioration. As a further option, Audi can supply an enhanced tyre pressure monitoring system. It still calls upon information supplied by the ABS sensors, but identifies precisely which wheel may have suffered a puncture by monitoring the specific characteristic oscillation of the tyres.
The brake system is entirely new; it is tailored exactly to the profile of a sports car. All Audi TT models are fitted with disc brakes on every wheel. Newly developed brake pads on the front wheels generate around 15 percent higher friction, improving both braking response and performance.
High braking performance: 17-inch system
On the four-cylinder version, the front discs are ventilated and measure 312 mm in diameter; the rear discs have a diameter of 286 mm. The 3.2 quattro has a 17-inch brake system with four ventilated discs: the diameters are 340 mm at the front and 310 mm at the rear. The brake calipers are also available in iron grey as an alternative.
The brake servo has acquired a new ratio. As far as the driver is concerned, this means a very direct pedal feel with extremely short free travel and progressive braking action. The brake servo acts spontaneously and the braking performance can be controlled outstandingly across the entire range of deceleration.
The newly developed ESP electronic stabilisation program is designed both to suit the typical driving style of a sports car and to operate harmoniously with smooth, acoustically gentle intervention. Particular emphasis has been placed on shortening the braking distance. Its capabilities include dry-braking the discs in rain by intermittently applying the pads briefly to the discs. Brake assist is also featured.
Audi magnetic ride high-tech damping
Audi magnetic ride is the name of the optional damping technology that resolves the age-old conflict between comfort and driving dynamics without countenancing any of the otherwise unavoidable compromises. As a continuously adaptive system, it adapts the damping characteristic to the profile of the road and the driver's gear-shifting habits within just a few milliseconds. None of the TT's competitors has such an efficient high-tech solution to offer. Audi magnetic ride is available as an option for both engine versions.
The shock absorber pistons on the TT do not contain conventional oil, but a magneto-rheological fluid a synthetic hydrocarbon oil in which microscopically small magnetic particles measuring between three and ten microns are enclosed.
When a voltage is applied to a coil by means of a pulse delivered by a control unit a magnetic field is created in which the alignment of the particles changes. They position themselves transversely to the direction of flow of the oil, and so inhibit its flow through the piston channels. This alters the characteristic of the damping characteristic much faster than is the case in conventional adaptive dampers.
Two programs: comfortable or crisp
Audi magnetic ride provides the right degree of damping force at each individual wheel in every situation. The control unit, supplied by complex sensing technology, constantly analyses the situation. Starting from the "Normal" setting, the driver can also activate the "Sport" mode via a button on the centre console. These two programs establish clearly distinctive characteristics.
In the basic mode when the oil is more viscous and the degree of damping less pronounced the TT rolls surprisingly smoothly; this is ideal for long-distance driving or uneven road surfaces. In the Sport mode, by contrast when the oil is less viscous it reveals an extremely dynamic character that is manifested by a resolutely firm grip of the road surface. Rolling movements are suppressed from the very moment the steering is turned even more effectively than in the basic suspension setting, and the steering response is further improved. The self-steering behaviour is further optimised by the specific stabilisation provided for each individual wheel, resulting in a driving feel reminiscent of a go-kart.