{"product_id":"je-pistons-fsr-forged-piston-kit-subaru-wrx-sti-ej20-ej25-10000mm-bore-1510cc-dish","title":"JE Pistons FSR Forged Piston Kit - Subaru WRX STI (EJ20\/EJ25) - 100.00mm Bore -15.10cc Dish","description":"\u003ch2\u003eJE Pistons FSR Forged Piston Kit - Subaru WRX STI (EJ20\/EJ25) - 100.00mm Bore, -15.10cc Dish\u003c\/h2\u003e\n\n\u003cp\u003eWhen you're building a serious EJ-powered Subaru, the pistons are one area where you simply cannot cut corners. JE Pistons brings over 75 years of forged piston development to this FSR series kit, engineered and machined entirely in the USA from 2618 aluminium alloy — the material of choice for high output and forced induction applications where thermal cycling and detonation resistance matter most. This isn't an off-the-shelf compromise; it's a purpose-built forging designed around the specific demands of the \u003cstrong\u003eSubaru WRX STI EJ20\/EJ25\u003c\/strong\u003e engine family.\u003c\/p\u003e\n\n\u003cp\u003eThis listing covers the JE Pistons FSR forged piston kit for the \u003cstrong\u003eSubaru WRX STI\u003c\/strong\u003e running the \u003cstrong\u003eEJ20\u003c\/strong\u003e or \u003cstrong\u003eEJ25\u003c\/strong\u003e engine (cylinder head: \u003cstrong\u003eEJ257 STI\u003c\/strong\u003e), at a finished bore diameter of \u003cstrong\u003e100.00mm\u003c\/strong\u003e with a \u003cstrong\u003e-15.10cc dish\u003c\/strong\u003e piston head. Please confirm your bore size and target compression ratio before ordering.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eNote:\u003c\/strong\u003e These pistons are supplied at 100.00mm bore. Your machine shop must confirm final bore sizing and piston-to-wall clearance to suit your specific build. Compression ratio will vary depending on your head gasket thickness, deck height, and chamber volume — use a compression calculator with your engine's exact dimensions before purchase.\u003c\/p\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eForged from 2618 aluminium alloy for exceptional strength and resilience under high heat and cylinder pressure\u003c\/li\u003e\n  \u003cli\u003eFSR (Forged Side Relief) design reduces skirt width, lowering friction and parasitic power loss while trimming overall piston weight\u003c\/li\u003e\n  \u003cli\u003eShorter wrist pin enabled by the FSR forging design further reduces reciprocating mass\u003c\/li\u003e\n  \u003cli\u003eSkirt coating reduces friction and wear against cylinder walls, with the added benefit of quieter operation\u003c\/li\u003e\n  \u003cli\u003eAccumulator groove (where applicable) relieves combustion gas pressure from behind the top ring, reducing ring flutter and improving ring seal consistency\u003c\/li\u003e\n  \u003cli\u003eEngineered specifically for the EJ257 STI cylinder head geometry, including valve pocket profiling\u003c\/li\u003e\n  \u003cli\u003eKit includes four pistons, wrist pins, retaining locks, and JE Pro Seal premium piston rings\u003c\/li\u003e\n  \u003cli\u003e100% designed, forged, and machined in the USA\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003ePiston series: JE FSR\u003c\/li\u003e\n  \u003cli\u003eMaterial: 2618 aluminium alloy\u003c\/li\u003e\n  \u003cli\u003eBore diameter: 100.00mm\u003c\/li\u003e\n  \u003cli\u003ePiston head type: Dish\u003c\/li\u003e\n  \u003cli\u003ePiston volume: -15.10cc\u003c\/li\u003e\n  \u003cli\u003eCompression height: 30.73mm (1.210 in)\u003c\/li\u003e\n  \u003cli\u003eAverage piston weight: 391g\u003c\/li\u003e\n  \u003cli\u003eQuantity: 4 pistons\u003c\/li\u003e\n  \u003cli\u003eTop compression ring thickness: 1.22mm (0.0480 in)\u003c\/li\u003e\n  \u003cli\u003eSecond compression ring thickness: 1.22mm (0.0480 in)\u003c\/li\u003e\n  \u003cli\u003eOil ring thickness: 2.53mm (0.0995 in)\u003c\/li\u003e\n  \u003cli\u003eWrist pin outer diameter: 22.99mm (0.905 in)\u003c\/li\u003e\n  \u003cli\u003eWrist pin length: 57.15mm (2.250 in)\u003c\/li\u003e\n  \u003cli\u003eWrist pin wall thickness: 4.57mm (0.180 in)\u003c\/li\u003e\n  \u003cli\u003eIntake valve pocket depth: 9.40mm (0.370 in)\u003c\/li\u003e\n  \u003cli\u003eIntake valve pocket diameter: 57.53mm (2.265 in)\u003c\/li\u003e\n  \u003cli\u003eIntake valve angle: 21°\u003c\/li\u003e\n  \u003cli\u003eExhaust valve pocket diameter: 47.50mm (1.870 in)\u003c\/li\u003e\n  \u003cli\u003eExhaust valve angle: 21°\u003c\/li\u003e\n  \u003cli\u003eRing set included: Yes (JE Pro Seal)\u003c\/li\u003e\n  \u003cli\u003eCylinder head: EJ257 STI\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eFitment details, compatible engine codes, and any additional application notes are provided in the tabs above. Please confirm your engine variant, bore size, and build specifications before ordering.\u003c\/p\u003e\n\n\u003cp\u003eNot sure if this kit suits your build? Contact our team at \u003ca href=\"mailto:sales@chicaneaustralia.com.au\"\u003esales@chicaneaustralia.com.au\u003c\/a\u003e for expert advice.\u003c\/p\u003e","brand":"JE Pistons","offers":[{"title":"Default Title","offer_id":52616407843109,"sku":"286463","price":3300.0,"currency_code":"AUD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0918\/2943\/6709\/files\/public.jpg?v=1781848189","url":"https:\/\/www.chicaneaustralia.com.au\/products\/je-pistons-fsr-forged-piston-kit-subaru-wrx-sti-ej20-ej25-10000mm-bore-1510cc-dish","provider":"Chicane Australia","version":"1.0","type":"link"}