{"product_id":"mahle-subaru-wrx-2-5l-ms-forged-piston-set-100mm-bore-79mm-stroke-8-5-1-cr","title":"Mahle [04-21 WRX STI] MS Forged Piston Set - 100mm Bore, 79mm Stroke, 8.5:1 CR","description":"\u003cp\u003eThe Mahle MS forged piston set is designed for Subaru WRX STI 2.5L EJ257 applications requiring a 100mm bore, 79mm stroke, and 8.5:1 compression ratio. Part number MHL930285037 includes four pistons engineered from 4032 aluminum alloy, with phosphate and Grafal coatings for performance-oriented engine builds.\u003c\/p\u003e\n\u003cp\u003eEach piston features a 100.0mm bore diameter, 30.7mm compression height, 79.0mm stroke specification, 130.5mm rod length, and a 23mm wrist-pin diameter. The set is designed around a -19.3cc dish volume and an 8.5:1 compression ratio (with 56cc cylinder head), making it suitable for compatible EJ257 engine combinations and rebuilds. The pistons weigh approximately 405 grams each and are supplied as a set of four.\u003c\/p\u003e\n\u003cp\u003eMahle's PowerPak piston assemblies include forged pistons, piston rings, pins, and wire locks in one race-proven package. The pistons are hand-deburred and then coated with dry phosphate to protect against ring micro-welding and pin galling during initial startup, with Mahle's proprietary Grafal anti-friction coating on the piston skirts to reduce drag, scuffing, and piston noise. The 4032 alloy offers a balance of strength and thermal stability for street and performance use. Compatible with stock sleeves; no aftermarket sleeves required.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e100.0mm bore (+.5mm over), 79.0mm standard stroke, 8.5:1 CR\u003c\/li\u003e\n\u003cli\u003eFor Subaru WRX STI 2.5L EJ257 (2004-2021)\u003c\/li\u003e\n\u003cli\u003e4032 aluminum alloy with phosphate and Grafal coatings\u003c\/li\u003e\n\u003cli\u003eLow drag rings, steel pins, and round wire locks included\u003c\/li\u003e\n\u003cli\u003eCompatible with stock cylinder sleeves\u003c\/li\u003e\n\u003cli\u003eSet of four; 405g per piston\u003c\/li\u003e\n\u003cli\u003eMahle part number 930285037\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Mahle","offers":[{"title":"Default Title","offer_id":47258122551398,"sku":"mhl930285037","price":631.1,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0075\/8703\/7237\/files\/20ec53a988c702bad53205c060cd21fd.jpg?v=1790174620","url":"https:\/\/jdmuscleusa.com\/products\/mahle-subaru-wrx-2-5l-ms-forged-piston-set-100mm-bore-79mm-stroke-8-5-1-cr","provider":"JDMuscle","version":"1.0","type":"link"}