inc. GST

SKU: J321240

BRAND: JE Pistons

LS1 Extreme Duty Asymmetrical FSR Flat Top Forged Piston
3.905" bore, 3.622" stroke, 6.098" rod length, -2cc dome volume

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We have redesigned and expanded our GM LS1 series product lines! These new pistons utilized our dedicated Forged Side Relief (FSR) forging that was specifically designed for high output GM LS1 series engines. In addition we have found ways to reduce weight and maintain the durability needed for both street and racing use. Lightweight and extremely durable, these pistons are machined for 1.5mm, 1.5mm, 3.0mm rings. Wrist pin upgrade recommended above 800hp.


  • Pin #945-2250-15C (105g)
  • Round Wire Locks # 927-073-MW


  • High strength FSR forging
  • Accumulator Grooves
  • Double Pin Pin

Piston Specifications

  • Bore Diameter: 3.905
  • Compression Height: 1.340
  • Compression Ratio with 64cc chamber volume: 10.4
  • Compression Ratio with 66cc chamber volume: 10.2
  • Compression Ratio with 72cc chamber volume: 9.6
  • Piston Volume: -2
  • Cylinder Head: LSX/L92 12 DEG
  • Piston Pin Outside Diameter: 0.945
  • Piston Pin Length: 2.250
  • Piston Pin Material: 5115
  • Ringset Included: No
  • Top Compression Ring Thickness: 0.06
  • Second Compression Ring Thickness: 0.06
  • Oil Ring Thickness: 0.1175
  • Piston Material: 2618
  • Forging Type: FSR
  • Piston Avg Weight: 436
  • Pin Wall Thickness: 0.150
  • Piston Type: Flat

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