GM LS1 4340 Forged Crank - 4.000 Stroke

The EAGLE GM LS1 4340 Forged Crank with 4.000 stroke is a premium forged crankshaft engineered for high-performance LS-series engine builds. Constructed from 4340 forged steel, this crankshaft delivers the strength and reliability required in forced-induction and high-RPM applications where durability under extreme loads is non-negotiable. The 4.000-inch stroke geometry is foundational to displacement calculations and engine architecture in LS platform builds, directly influencing torque characteristics and overall engine displacement.

This internally balanced forged crankshaft accommodates the one-piece rear seal design standard to GM LS-series engine blocks, streamlining installation and reducing potential leak points at the block interface. The 4340 forged steel material provides superior fatigue resistance and material density compared to cast alternatives, a critical advantage when building engines destined for turbocharged, supercharged, or high-boost applications. The internal balance specification means this crank is pre-optimized to work with matched LS rotating assemblies, eliminating guesswork in balancing tolerances and reducing machine shop costs during engine assembly.

Builders pursuing serious LS engine upgrades—whether for bracket racing, street performance, or marine propulsion—require a crankshaft that can survive sustained power levels without risk of crank failure. The EAGLE LS1 forged crank addresses this by combining proven 4340 material science with tight manufacturing tolerances. Engine builders integrating this crank into stroker packages or displacement-increased builds will find the 4.000-inch stroke spec to be a well-established choice within the LS tuning community, supported by extensive parts compatibility and proven durability records in the field.