The second generation S4, now correctly titled Audi S4 quattro debuted in 1997.
The powertrain of the S4 features a 2.7L twin-turbo (‘biturbo’) V6 engine. Detail of the powerplant includes a cast iron cylinder block with two lightweight aluminum alloy cylinder heads. It displaces 2,671 cubic centimeters (163.0 cu in), and is rated to produce a motive power output of 261 bhp at 5,800 revolutions per minute (rpm), and generates 400 newton meters (295 ft·lbf) of torque at 1,850 rpm.
In the North American market, the engine was slightly detuned to meet US emissions regulations, output was reduced to 251 bhp and 350 newton meters (258 ft·lbf).
The S4 claims acceleration from 0 to 100 kilometers per hour in 5.6 seconds, and had an electronically-limited top speed of 250 km/h (155.3 mph).
Source: Wikipedia, 2011