Join Date: Mar 2001
· For the TT, a fourth joining technique has also been added: self-tapping screws, inserted by robots, melt the surface of the component as a result of the friction they cause, thus penetrating fully into the material, forming a positive connection with it.
· Thanks to engine encapsulation and the body’s space frame design, the TT Roadster has an underbody which is smooth throughout almost its entire length in the style of a racing car, minimising air flow obstruction and reducing lift. Precision details such as the rear silencer, which is sloped downwards by 7 degrees to double as a diffuser, help to maximise aerodynamics. The latest TT Roadster has recorded an impressively low drag coefficient of 0.32.
· The new TT Roadster makes no compromises when it comes to crash safety as well, even though the relatively short forward structure means that only a limited amount of deformation space is available in the event of a head-on collision. Audi's engineers solved this problem by calling on the experience they had gathered in developing the ultra-compact A2.
· The longitudinal members in the forward structure comprise aluminium extruded sections towards the front and high-load castings in the transition to the passenger compartment. Together with the front cross-member and the subframe, which is bolted to the forward structure at six points, this assembly reduces and distributes the kinetic energy that acts in a head-on collision. It thus keeps the passenger compartment as intact as possible, allowing a coordinated form of interaction with the restraint systems.
· At the rear end, there are large-volume members to protect the passenger compartment.
· High-strength aluminium profiles in the doors and robust side sections resist the worst of a side impact. The floor of the passenger compartment is reinforced by transverse extruded sections. A roof frame reinforced in specific areas affords a high level of protection in the event of a sideways roll-over.
· The car's passive restraint systems are also state-of-the-art. Depending on the severity of the impact, the driver and passenger airbags are activated in two stages; they receive their signals from an up-front sensor that detects a collision particularly early thanks to its installed position at the nose of the vehicle. Belt tensioners and belt force limiters on the front seats protect the driver and front passenger.
· The steering column has a defined crumple zone of 100 millimetres. A mechanism uses the relative movement between the bulkhead and the driving-area cross-member to swing the pedals away from the driver's feet.
· Side airbags are fitted on pillars inside the seat backs for head and thorax protection. The Audi backguard system supports the back of the head by means of the head restraint in a rear-end collision, to counteract the danger of whiplash injuries.
· The TT Roadster is 137 mm longer and 78 mm wider than its predecessor, but only 8 mm higher. It is now 4,178 mm long, 1,842 mm wide and 1,358 mm high. The TT's wheelbase is 2,468 mm (plus 45 mm).
· This growth has by and large been translated into increased space inside: it has become noticeably more spacious and airy. Inside, the front shoulder width has increased by 29 mm to 1,352 mm, and luggage compartment capacity has also increased from 180 or 220 litres in the outgoing front-wheel-drive and quattro TT Roadster to 250 litres for both 2.0 TFSI and 3.2 quattro versions of the latest car.
THE SOFT TOP
· To avoid negating the weight saving made possible by the new construction technology, the new TT Roadster retains a cloth hood which is electro-hydraulically powered in both versions.
· When the hood is in place, the coefficient of drag in the 2.0 TFSI is reduced to an impressively low 0.32
· Incorporating a heated glass rear window, and available in black or dark grey, the new soft top is both lighter than before through the use of a new steel and aluminium support framework, and even more insulating thanks to an additional layer of soundproofing.
· Operation is now completely ‘hands-free’, with no need to attach or detach the hood to or from the windscreen rail, and the full opening or closing process takes place in just 12 seconds, and can be carried out at speeds of up to 19mph.
· The soft top also stows even more neatly and space efficiently than before thanks to a new Z-fold system which stacks the rigid front section of the roof on top of the cloth to form a cover resting flush with the body and eliminating the need for a tonneau
· A powered mesh wind deflector is also fitted as standard to UK TT Roadster models to streamline airflow through the cabin and minimise buffeting
· The new Audi TT Roadster is available from launch with a choice of two transversely mounted petrol engines –
- 2.0 TFSI four-cylinder developing 200PS, 280 Nm
- 3.2 V6 developing 250PS, 320 Nm
The 2.0 TFSI
· The direct-injection four-cylinder turbo or ‘TFSI’ engine has a displacement of 1,984 cm3, and combines FSI petrol direct injection, which Audi developed, with exhaust-driven turbocharging. An international jury of experts voted it "Engine of the Year" for two years in succession, in 2005 and 2006.
· An entirely newly developed engine and the first to combine turbo charging with FSI petrol direct injection incorporating a common rail injection system and a single-piston high-pressure injection pump. Four valves per-cylinder, double overhead camshafts, 1,984cc
· In contrast to indirect injection, the fuel is injected directly into the combustion chamber. Located on the admission side in the cylinder head, the injector 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 fuel-air mixture is distributed purely homogeneously within the combustion chamber, placing the emphasis on engine response and performance
· Engine block is made from GG25 grey cast iron, a material known for its high pressure resistance and excellent acoustic properties
· Intake manifold is made from a high-tech plastic and incorporates charge movement flaps adjusted by a continuous-action pilot motor. This ensures that optimum airflow movement can be controlled taking engine speed and load conditions into account
· The four-valve cylinder head with low-friction roller cam follower drive has modified inlet duct geometry for even higher tumble values than the naturally aspirated FSI engine. This not only boosts refinement but also knock resistance for increased efficiency
· The result is a compression ratio of 10.3:1, a figure normally only achieved by naturally aspirated engines
· Broad plateau of torque (280Nm from 1,800rpm right up to 5,000rpm) permits a fuel-efficient driving style with minimal gear changes and also ensures optimum throttle response
Excellent noise and vibration suppression is achieved thanks to two balancing shafts rotating at double the speed of the crankshaft which compensate for the engine's inertial forces. The crankshaft transmits power by means of a triangular-layout chain that drives the oil pump and the balancing shafts. A specially tuned exhaust system ensures that the consistently strong performance from the 2.0 TFSI is accompanied by consistently sporty acoustics that perfectly suit the character of the new TT Roadster
The Audi TT Roadster with 2.0 TFSI engine accelerates from rest to 62mph in just 6.5 seconds (in the version featuring the S tronic dual-clutch gearbox) and on to a top speed of 147mph. It achieves this impressive performance while at the same time covering up to 36.2mpg on the combined cycle.
The 3.2 V6
· Many aspects of the 3.2-litre V6 petrol engine have been revised since its original installation in the previous TT. Perhaps the most significant of these revisions is the modification to the engine mapping that has resulted in much improved throttle response across all engine speed ranges
· Achieving peak torque of 320 Nm from as low as 2,500 to 3,000 rpm, and an output of 184 kW (250 bhp) at 6,300 rpm from a 3,189 cm3 capacity, the 3.2-litre V6 is a relaxed powerhouse
· On the road, a carefully tuned intake-based engine note does full credit to this powerful, large capacity engine at all speeds
· Despite its cylinder count the V6 is suitable for installation transversely to the direction of travel thanks to an 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.
· The TT Roadster 3.2 quattro with the six-speed gearbox sprints from a standing start to 62mph in 5.9 seconds (with S tronic) on the way to an electronically limited top speed of 155mph, yet even with these exceptional capabilities manages to remain impressively economical with fuel, covering up to 29.7mpg (combined cycle, with S tronic).
· Both versions of the new Audi TT Roadster can be equipped with two transmission variants, but the standard spec for both is a six-speed manual gearbox in a lightweight magnesium casing
· A short-shift six-speed manual gearbox with an even further reduced shift throw is available as an optional extra costing £150 for both versions
· S tronic transmission (formerly known as DSG) is an optional extra costing £1,400 for both models. Combining the advantages of an automatic transmission with those of a manual gearbox thanks to innovative dual-clutch technology, the six-speed transmission can make a gear change in a breathtaking 0.2 of a second, without interrupting the power flow, enabling the driver to derive maximum benefit from the engine’s output at all times.
· S tronic basically consists of two three-speed transmissions, each with their own clutch, accommodated in a single housing. The two multi-plate clutches are located close to each other, the first one serving the odd-numbered gears and reverse, and the second 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 antici pation. 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.
· 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 transmission can be operated by means of the one-touch lever or manually via the shift paddles on the steering wheel. It can operate in either normal Drive mode or in Sport mode, activated by moving the lever to the S position, which activates 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 Audi TT Roadster with the four-cylinder TFSI engine is launched in front-wheel-drive form, while the V6 features permanent four-wheel drive. Its quattro drive system, developed specially for transversely-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 mechanical construction and precision of the control function have been further enhanced compared with the system fitted to the original TT, and service intervals for the quattro system as a whole are also double the length of its predecessor at approximately 37,000 miles.
· 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.
· 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, translating into optimum safety and driving pleasure.
· Within the clutch the package of plates, which runs in an oil bath, 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 rapid pressure build-up. 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.