Part Number: FCPPA830085RS4Manufacturer: FCP EngineeringForged high-performance pistons for a variety of applications in almost all engine types, for both racing and street use. Made of 4032-T6 material, the bottom of the piston is molybdenum coated. Each piston kit also includes rings and HD series pistons. Cylinder diameter: 83.00 mm Compression ratio (CR): 8.5:1 Compression height: 30.80 mmPiston diameter: 21mm Stroke: 86.40 mmAudi S4 RS4 - 2.7 30V Biturbo