CP Pistons Forged Pistons (Stroker) – Subaru EJ257 - Chicane Australia
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CP Pistons Forged Pistons – Subaru EJ257

$1,799.00
SKU: SC7420
Bore - CR:99.50mm / CR 8.2
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Estimated shipping: 7 - 10 Days
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CP Pistons – Subaru EJ257 WRX STI Forged Piston Set (79mm Stroke)

Built for serious turbocharged Subaru EJ257 applications, the CP Pistons Forged Piston Set offers race-proven reliability and precision. Manufactured from high-strength aluminium and designed for a 79 mm stroke and 130.5 mm rod length, this piston series suits aggressive street, time attack, and track builds demanding a strong and lightweight rotating assembly.

These pistons feature deep valve reliefs, anti-detonation grooves, and fully CNC-machined domes for consistent combustion, optimised flow, and maximum durability under boost.

Key Features

  • Designed for EJ257 engines with 79 mm stroke
  • Forged aluminium for high strength and reduced weight
  • Wide range of compression ratios (8.2, 8.4, 9.0, 10.0)
  • Available in standard and oversized bore diameters
  • Supplied with pins, rings, and locks

Available Variants

Variant Part # CR Dome/Dish (cc) Bore (mm) Weight (g)
99.50mm / CR 8.2 SC7420 8.2:1 -21.00 99.50 392
99.50mm / CR 9.0 SC7425 9.0:1 -14.20 99.50 401
99.50mm / CR 10.0 SC7415 10.0:1 -7.40 99.50 438
99.75mm / CR 8.2 SC7422 8.2:1 -21.00 99.75 392
99.75mm / CR 9.0 SC7426 9.0:1 -14.50 99.75 404
99.75mm / CR 10.0 SC7416 10.0:1 -7.40 99.75 439
100.00mm / CR 8.2 SC7421 8.2:1 -21.00 100.00 408
100.00mm / CR 9.0 SC7427 9.0:1 -14.90 100.00 408
100.00mm / CR 10.0 SC7417 10.0:1 -6.30 100.00 440
100.50mm / CR 8.2 SC7423 8.2:1 -23.10 100.50 393
100.50mm / CR 9.0 SC7428 9.0:1 -15.60 100.50 399
100.00mm / CR 8.4 SC7431 8.4:1 -6.93 100.00 440

Technical Overview

  • Stroke: 79 mm
  • Rod Length: 130.5 mm
  • Compression Height: 1.208 in
  • Wrist Pin: 23 mm (0.9055 in), included – 905-2500-18CP1S
  • Ring Pack: 1.0 mm / 1.2 mm / 2.8 mm – 905x055 SUB
  • Locks: Spiral locks (part numbers vary)
  • Vehicle Fitment: Subaru EJ257 WRX STI

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