S3 Performance and efficiency
Audi is launching a new, powerful PETROL engine in the S3.
The 2.0 TFSI for the sporty compact car represents the current state-of-the-art.
The dynamics of the new Audi S3 place it at the very top of its class. In combination with the optional S tronic, the sprint from zero to 100 km/h is over in just 5.1 seconds, and in 5.4 seconds with the manual transmission. The electronically limited top speed of 250 km/h is simply a formality for both versions. Nevertheless, the S3 with the S tronic consumes an average of just 6.9 liters of fuel per 100 km, equating to COâ‚‚ emissions of 159 grams per km. A start/stop system contributes to this impressively low figure.
The 2.0 TFSI represents a further milestone in Audi’s downsizing strategy. Developed from scratch, all it has in common with its predecessor is its displacement of 1,984 cm³ (bore x stroke 82.5 x 92.8 millimeters). The four-cylinder has a compact and lightweight construction – at 148 kilograms, it weighs more than five kilograms less than the previous engine. Its rated output of 221 kW (300 hp) is available at 5,500 rpm; the limiter kicks in at 6,800 rpm. Across a wide rev range between 1,800 and 5,500 rpm, it sends 380 Nm through the crankshaft. And, as a true sports engine, the four-cylinder has an incredibly spontaneous throttle response.
Two balancer shafts that contra-rotate at twice the speed of the crankshaft ensure a very high level of mechanical refinement. The sound produced by the two-liter unit has a rich intensity and sporty depth when the Audi drive select system, which is standard equipment, is running in “dynamic” mode. The engine also reacts faster to input from the gas pedal in this mode, while short fuel burn-offs accompany the S tronic gearshifts. Under high loads and engine revs, both of the sound flaps on the exhaust system open for an even fuller tone.
Many details underscore the high-performance character of the new four-cylinder. Modified aluminum pistons and higher-strength conrods with new bearings transmit the power to the crankshaft. The grey cast iron crank case now has stiffening at the mainbearing seats and main-bearing cover. The cylinder head is made from a new, high-strength aluminum-silicon alloy that boasts excellent thermal stability and low weight. The hollow exhaust valves are filled with cooling sodium.
The large turbocharger, which is also brand new, is set up to handle exhaust temperatures of up to 1,000 degrees Celsius. With its maximum charge pressure of 1.2 bar, it has a theoretical throughput of 1,000 kilograms or 850,000 liters of air per hour. A high-performance air-to-air intercooler reduces the temperature of the compressed air significantly, thus increasing the mass available for combustion. The electronically controlled wastegate operates extremely quickly and precisely, reducing the pumping work required because it decreases charge pressure and, with it, exhaust back pressure.
|Power||221 kW (300 hp) at 5,500 rpm|
|Maximum torque||380 Nm from 1,800 to 5,500 rpm|
|0 – 100 km/h||5.1 s (S-tronic)|
|Vmax||250 km/h (electronically limited)|
|Consumption||6.9 liters per 100 km|
|COâ‚‚ emissions||159 grams per km|
The 2.0 TFSI comes with groundbreaking solutions across a host of technical disciplines. One of them is the additional indirect injection supplementing the FSI gasoline direct injection under partial load. This lowers fuel consumption and particulate emissions – the four-cylinder already complies with the limits imposed by the second phase of the Euro 6 standard due for implementation in 2017. FSI injection, which operates at pressures of up to 200 bar, comes into its own on start up and under higher loads. Each of the enlarged injection valves has six holes.
The four cylinders are always well filled. The intake camshaft is fully adjustable through 60 degrees of crank angle; the exhaust camshaft through 30 degrees. The Audi valvelift system also varies valve lift in two stages on the exhaust side. So-called drumble flaps (from “Drall”, the German word for swirl, and tumble) set the in-flowing air into a specific pattern of movement. Compression is 9.3 : 1, which is unusually high for a turbocharged engine.
The exhaust manifold is integrated into the cylinder head, where it is bathed in coolant. This solution reduces exhaust gas temperature and accelerates warm-up under cold-start conditions. The innovative thermal management of the 2.0 TFSI includes two rotary disc valves in a single module to regulate coolant flow. They ensure that the engine oil reaches operating temperature quickly after start up, and set the coolant temperature at between 85 and 107 degrees Celsius depending on the driving situation. This delivers the best relationship between minimal friction and a high degree of thermal efficiency at every load and engine speed. A new kind of coating on the piston bodies and antifriction bearings on the balancer shafts keep friction low, while the oil pump is regulated to work on-demand.