GM LS 4340 Forged Crank - 4.000 Stroke

The EAGLE GM LS 4340 Forged Crank with 4.000 Stroke is a premium forged crankshaft engineered for GM LS-series engine builds demanding maximum reliability and performance. Constructed from 4340 forged steel, this crankshaft delivers the strength required for high-output LS engines while maintaining the internal balance characteristics essential for smooth, vibration-free operation across a wide RPM range. The 4.000-inch stroke specification is a proven displacement platform for builders seeking the performance envelope between standard and maximum-stroke variants.

The 2-piece seal design accommodates modern LS engine bay configurations while maintaining the durability and sealing integrity critical for oil containment in high-performance applications. Forged 4340 steel provides superior fatigue resistance compared to cast alternatives, a critical advantage when the crankshaft faces the cyclic loading demands of naturally aspirated, turbocharged, or supercharged builds. The precision manufacturing ensures concentricity and finish specifications that minimize friction losses and extend bearing life. At 61 pounds, this component delivers the mass characteristics LS builders require for balanced engine dynamics.

This crankshaft is purpose-built for LS engine builders and machine shops constructing performance, street, and race engines where displacement and stroke length form the foundation of the build strategy. The 4.000-stroke platform supports displacement targets from 408 to 427 cubic inches depending on bore selection, making it the preferred choice for builders balancing torque output with component compatibility and turbo spool characteristics. Proper installation requires alignment with complementary components—rods, pistons, and dampers—to realize the full potential of the forged construction.