CP Piston & Ring Set for Subaru EJ257 WRX STi – Bore (99.75mm) – Size (0.25mm) – CR (8.2)

SKU: SC7422-4

CP Piston & Ring Set for 2004-2014 Subaru Impreza WRX STI EJ257 – Bore 99.75mm – Size 0.25mm – CR 8.2

CP forged piston and ring set SC7422-4 delivers reliable power for Subaru EJ257 turbo engines in 2004-2014 Impreza WRX STI models. This 0.25mm oversize kit features 99.75mm bore and 8.2:1 compression ratio to support high-boost setups while ensuring engine durability. Includes matched rings and pins for complete rebuild readiness in performance Subaru builds.

Key Features

• Forged 2618-T61 Alloy: Provides high tensile strength to handle extreme cylinder pressures in turbo EJ257 applications
• Accumulator Groove Design: Reduces ring flutter under high RPM and boost for improved sealing and power retention
• Skirt and Crown Coatings: Anti-friction skirt coating lowers drag, while crown coating protects against detonation in boosted environments
• Precision Ring Pack: Includes forged steel top ring, cast iron second ring, and three-piece oil ring set for optimal compression and oil control
• 30mm Compression Height: Matches EJ257 specs with 22mm x 1.02mm wrist pins and spiro-locks for direct fit after machining

Product Notes

• Engine block must be bored and honed to 99.75mm prior to installation
• Pistons ship balanced as a matched set of four
• Inspect rods and bearings during rebuild for best results

Installation Notes

• Professional installation recommended.
• Requires cylinder boring to 99.75mm and ring gap verification per CP guidelines
• Compatible with stock EJ257 connecting rods. ARP rod bolts advised for high boost

This Part Fits

Year	Make	Model	Submodel
2004-2012	Subaru	Impreza	WRX STI
2007	Subaru	Impreza	WRX STI Limited
2011-2012	Subaru	Impreza	WRX STI Limited
2010	Subaru	Impreza	WRX STI Special Edition
2013-2014	Subaru	Impreza	WRX STI

Why Choose CP Pistons?

• Engineered for motorsports with decades of piston forging experience
• Hand-built in the USA for consistent quality in every set
• Proven design trusted in drag racing and rally Subaru builds

Frequently Asked Questions

• Q: Does this fit all EJ257 engines in 2004-2014 STI models?
  A: Yes, designed specifically for EJ257 2.5L DOHC turbo in USDM Impreza WRX STI variants after block machining to 99.75mm bore
• Q: What material are the pistons made from?
  A: Forged from 2618-T61 aluminum alloy with hard anodized top ring grooves and anti-friction coatings for durability
• Q: What warranty is included?
  A: Limited lifetime warranty against manufacturing defects when installed by certified professionals

Shipping & Handling

• Method: UPS Ground or FedEx Ground
• Availability: In stock – ships same or next business day
• Packaging: Securely boxed with foam protection
• Weight: 5.8 lbs