Part number: FCPP845085RS6 Manufacturer: FCP Engineering Forged high performance pistons for various applications in nearly all engine types for racing and street use. Made of 4032-T6, piston skirt is molibden coated. Each set of pistons also includes rings and HD series pins. Bore size: 84.50mm Compression ratio (CR): 8.5:1 Compression height: 30.70 mm Pin diameter: 21mm Stroke: 93.00mm Audi RS6 C5 - 4.2 40V V8 Biturbo (BCY, BRV)