Part Number: FCPPB845085M50: FCP Engineering Forged high performance pistons for a variety of applications in almost all types of racing and street engines. Made of 4032-T6, molybdenum coated piston bottom. Each piston kit also includes HD series rings and welded studs. Cylinder diameter: 84.50 mm Compression Ratio (CR): 8.5:1Compression height: 32.50mmPin diameter: 22mmStroke: 75.00mmBMW 325 525 Turbo (M50B25, M52B25TU)Piston length must be 140mm