CP Piston & Ring Set for Subaru EJ257 WRX STi - Bore (99.75mm) - Size (0.25mm) - CR (8.2) CP Pistons CPPSC7422-4
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CP Piston & Ring Set for Subaru EJ257 WRX STi - Bore (99.75mm) - Size (0.25mm) - CR (8.2)

CP Pistons
CPPSC7422-4
Piston Sets - Forged - 4cyl
3 Units In Stock - Ships Next Business Day
$ 885.15
$ 885.15

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

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