Every set is built to order. Please allow five weeks for it to ship.
Diamond Pistons forged piston kit for the EJ257 (WRX STI), set of 4. ASF Machine orders these direct from Diamond for your build (not a stocked item). Diamond builds its sport compact pistons from forged 2618 aluminum, CNC-machines them, and pairs them with Trend Performance wrist pins.
Piston volume: -22cc; compression height: 1.208 in.
Stroke: 79mm; rod length: 5.137 in.
Ring set: 1.20 mm x 1.20 mm x 2.00 mm
Wrist pin: 0.905 in. OD x 2.500 in. long
Valve pocket depth: 0.220 in. intake, 0.220 in. exhaust
Forging: full round
Rings, wrist pins and pin retainers included (per Diamond)
Per Diamond: pin oiling fed from the oil ring, pins fitted to the pistons, 3D-machined valve pockets, moly-coated skirts, wrist pins, locks and (where needed) oil-ring support rails included
Diamond part numbers:
36011-4: 99.5mm bore, standard pin, 8.10:1 compression (per Diamond), ring set 09513917, wrist pin G9052500180SC
36011-4-H: 99.5mm bore, H13 pin, 8.10:1 compression (per Diamond), ring set 09513917, wrist pin H9052500225SC
36012-4: 99.75mm bore, standard pin, 8.10:1 compression (per Diamond), ring set 09513927, wrist pin G9052500180SC
36012-4-H: 99.75mm bore, H13 pin, 8.10:1 compression (per Diamond), ring set 09513927, wrist pin H9052500225SC
36013-4: 100mm bore, standard pin, 8.20:1 compression (per Diamond), ring set 09513937, wrist pin G9052500180SC
36013-4-H: 100mm bore, H13 pin, 8.20:1 compression (per Diamond), ring set 09513937, wrist pin H9052500225SC
36014-4: 100.5mm bore, standard pin, 8.30:1 compression (per Diamond), ring set 09513957, wrist pin G9052500180SC
36014-4-H: 100.5mm bore, H13 pin, 8.30:1 compression (per Diamond), ring set 09513957, wrist pin H9052500225SC
Specs and fitment: Piston kit, set of 4. -22cc, 1.208 in. compression height, 79mm stroke. Fits Subaru EJ257 (WRX STI). Ordered direct from Diamond Pistons; call 970-242-0919 to confirm fitment and lead time for your build.
