Overview 

The LS 4.125" forged steel crankshaft is a high-performance component designed for stroker builds and race-ready engines. Forged from premium 4340 steel, it offers exceptional strength and durability, making it ideal for engines producing high horsepower and torque. The crankshaft features large-radius fillets for added strength at critical stress points, and it is internally balanced to reduce vibrations and improve engine longevity. Precision CNC machining ensures tight tolerances, while the journals are micropolished for reduced friction and improved oiling. Many versions are heat-treated, nitrided, and shot-peened to increase surface hardness and fatigue resistance. Some models also include straight-shot oiling, a 58-tooth reluctor wheel, and long snouts for compatibility with dry-sump systems. Overall, it’s a reliable choice for high-RPM, high-load LS engine builds.

Features

• 4.125" stroke ideal for stroker LS engine builds and increased displacement

• Forged 4340 steel construction for high strength and durability under extreme loads

• Internally balanced to reduce vibration and improve engine longevity

• Large-radius fillets enhance strength at critical stress points

• CNC machined for precise fitment and tight tolerances

• Micropolished journals reduce friction and improve oil film stability

• Heat-treated and nitrided for increased surface hardness and wear resistance

• Shot-peened to improve fatigue life and crack resistance

• Straight-shot oiling (on some models) for better lubrication to bearings

• Available with 58-tooth reluctor and long snout for compatibility with dry-sump setups