This ZRP 2124 cc Stroker Kit is designed for Subaru EJ20 / EJ205 engines, as found in the WRX and STI (1998 and later). It includes the main internal components needed to build a performance-oriented, reinforced lower engine block, featuring a selection of forged parts designed to improve mechanical durability under heavy use (tuning, forced induction, and high thermal and mechanical loads). The included ZRP forged crankshaft is made of 4340 steel and designed for the EJ25 / EJ257 architectures. It has a stroke of 79.00 mm, a journal diameter of 60.00 mm, and a crankpin diameter of 52.00 mm, with a weight of 8.1 kg. This reinforced cankshaft is designed to offer better resistance to fatigue and torsional stress compared to a standard crankshaft, while allowing for the stroker configuration associated with the pack’s advertised cubic capacity. The included ZRP Pro Series forged connecting rods are of the I-beam type and compatible with the EJ20, EJ205, EJ25, EJ257, and EJ22ET engines. They feature a center-to-center length of 130.50 mm, a piston pin diameter of 23.00 mm, a conrod head diameter of 55.00 mm, and a head width of 17.00 mm. The included fasteners are made of ARP L19 with 3/8" threads, designed for high-stress applications and high RPMs/loads to ensure secure tightening and tensile strength of the connecting rod/piston crown assemblies. The kit also includes a set of Wiseco forged pistons designed for Subaru EJ20 / EJ205 WRX-STi (1998 and later). Detailed dimensional specifications for the pistons (bore, compression ratio, piston crown shape, recommended clearances) are not provided here; however, this component complements the crankshaft/connecting rod assembly to form a cohesive forged lower engine kit, designed for reliability and performance in a stroker configuration. Stated final cubic capacity: 2124 cc. Engine compatibilities listed in the description: EJ20, EJ205 (WRX/STI applications), with a crankshaft listed for EJ25/EJ257. Any final compatibility validation (crankcases, machining, bearings, balancing, engine management) must be performed based on the exact engine block configuration and power target, as these details are not specified in the information provided.
