HKS FA20 capacity upgrade kits with forged pistons, a longer-stroke crankshaft and matching connecting rods. Choose the compression and connecting-rod specification for the intended engine build.
FITMENT Toyota 86 / GT86 (ZN6) 2012–2021 — FA20. Subaru BRZ (ZC6) 2012–2021 — FA20. The years identify the vehicle generation. Confirm the engine revision, cylinder-head specification and selected kit before ordering. These are FA20 kits, not FA24 kits for the later GR86 / BRZ.
KIT VERSIONS 21004-AT002 — high-compression forged piston kit, I-beam connecting rods and forged crankshaft. 21004-AT003 — low-compression Step 1 forged piston kit, I-beam connecting rods and forged crankshaft. 21004-AT004 — low-compression Step 2 forged piston kit, billet I-beam connecting rods and forged crankshaft. The Step 2 rod specification differs from Step 1.
SPECIFICATIONS Engine: FA20 Bore: 86.0 mm Stroke: 90.0 mm Displacement: approximately 2,091 cc Piston pin diameter: 22 mm Compression ratio depends on the chosen piston kit, cylinder head and head gasket. HKS lists boring/honing and full-flow modification as not required for these standard-bore kits; the engine builder must assess the condition of the block.
PURCHASED PARTS PACKAGE Forged piston kit, the connecting rods specified for the selected version, and forged crankshaft. This is an internal-component kit, not an assembled engine.
INSTALLATION AND USE The matched crankshaft and connecting rods use specific bearing dimensions. HKS specifies separately purchased Nissan RB26 / SR-type connecting-rod bearings for the Step 1 arrangement. Have an engine builder confirm the correct bearings, clearances, head gasket, camshaft clearance and engine management for the selected kit.
