Special turbo geometry for Audi TT motor

A BorgWarner turbocharger with special geometry powers the 2.5-litre, five-cylinder Audi TT Motor

Audi recently presented the TT with a new, turbocharged five-cylinder in-line engine that sets new standards in terms of performance and driving pleasure. Displacing 2.5-litres, the completely new engine delivers 340 hp and a torque of 450 Nm at 1,600 rpm, which remains constant up to 5,300 rpm! Specifications of this nature are achieved by direct gasoline injection and turbo-charging. BorgWarner, which supplies the two-stage camshaft drive system to increase chain forces which come to bear on a turbocharged engine as compared to a naturally-aspirated one, also provides the turbo-charging system. The turbocharger is special in a way that it sports a special geometry to aid high performance. In fact, the special geometry as well as the requirement that the component weighs as low as possible made high demands on the casting and moulding engineering technology at BorgWarner. The cast-steel manifold of the exhaust-gas turbocharger is thus attached to the cylinder-head using tried-and-tested Audi clamping flange technology. This construction compensates for thermal expansion on the turbocharger.

Termed as K16 turbocharger, the unit features a relatively large compressor impeller and stands out due to its high efficiency over a wide operating range. At full-load operation the turbocharger compresses, in theory, some 335-litres of air per second; the relative boost pressure can amount to as much as 1.2bar. The turbocharger features a separate oil supply and is cooled by its own water pump. At full load, the charge-air intercooler reduces the temperature of the compressed air and achieves an efficiency of more than 80 percent. To guarantee the necessary high feed rate at the lower speed range, sufficient turbine output is always available even at low exhaust mass flow rates. The specialists from Kirchheimbolanden and quattro GmbH achieved the best possible utilisation of the outlet pulsation on the turbine rotor by adapting the manifold and turbine cross-sections. The K16 turbocharger in combination with the efficient Audi combustion process achieves and maintains a constant high BMEP level with excellent thermodynamic parameter values in the mid-speed range.

BorgWarner together with Audi broke new ground with the 2.0-litre four-cylinder diesel engine in the TT. Featuring a 170 hp engine with a BV43 turbocharger with third-generation variable turbine geometry, not only is the torque enhanced considerably but the engine also complies easily with the latest Euro standard. With a fuel consumption of just 5.5-litres of diesel per 100 km, the powerful 272 hp 2.0-litre TFSI engine in the TTS also benefits from the advanced K04 turbocharger system from BorgWarner. The K04 turbocharger with waste-gate features a pulsation muffler as well as a milled compressor impeller. It is also used by Audi in the S3.