CP Pistons Ring Set for SC7427 - Subaru EJ255/EJ257

High-performance replacement piston ring set for CP Pistons forged pistons, part number SC7427. Specifically designed for Subaru EJ255 and EJ257 turbo engines, this ring kit ensures optimal sealing and maximum performance under the most demanding conditions.

Important: This kit contains rings for ONE piston. Order 4 kits for a complete 4-cylinder set.

Technical Specifications

Main Specifications

• Manufacturer: CP Pistons
• Product reference: RS1658-3937-0
• Piston Compatibility: SC7427
• Bore: 100mm (+0.5mm)
• Compression ratio: 9.0:1

kit Configuration

• Compression ring (top ring): Gas-nitrided steel, cast iron compatible and Nikasil
• Oil ring: Tapered face for improved oil control
• Oil ring: Flex vent design for optimal control

CP Pistons Technologies

• Accumulation grooves: Collection of residual gases between rings superior and second
• Molly plasma treatment: Top face for optimal sealing
• High-strength ductile iron: Maximum durability
• Anti-Detonation Grooves: Protection against energy waves detonation

Applications

compatible Engines

• Subaru EJ255 - 2.5L DOHC 16v Turbo H4
• Subaru EJ257 - 2.5L DOHC 16v Turbo H4

Vehicles (examples)

• Subaru WRX STI (2004-2021)
• Subaru WRX (turbo versions)
• Performance and competition engine preparations

SC7427 compatible Piston Specifications

Installation Recommendations

Cylinder Preparation

• Frame angle: 35-40 degrees
• Roughness recommended:
  • Rz = 59-138 Auin (1.5-3.5 Aum)
  • Ra = 15-35 Auin (0.4-0.9 Aum)
• Finish: Fine abrasive stone (#400-#600) or plate brush

Set of Ring

Warranty and Mount

CP Pistons rings are covered by the manufacturer's warranty against manufacturing defects. Professional installation is highly recommended.

Important Notes

?? Attention:

• This kit is for ONE piston only
• Only suitable for CP pistons, part number SC7427
• OEM piston rings are NOT compatible with these pistons
• Professional installation recommended
• Always check clearances before installation
• Do not use the second piston ring if the piston only has 2 grooves (design) specific)

kit Contents

• 1x Compression ring (top ring)
• 1x Scraper ring (second ring) *
• 1x Oil ring with expander

* Some SC7427 pistons may be designed to use only the top ring and the oil ring (2-ring configuration). Check your piston configuration before installation.

Why Choose NSB Concept?

• Technical Expertise - Personalized Advice for your Project
• Genuine Parts - Official CP Pistons Distributor
• Fast Shipping - Stock Available in France
• Technical Mount - Pre- and post-sales assistance

For any technical questions or group orders, contact our team.