LS Alm. Block - 9.240/ 4.125 w/Steel Main Caps

The LS Alm. Block - 9.240/ 4.125 w/Steel Main Caps by DART is a premium aluminum engine block engineered for serious LS engine builders and performance enthusiasts who demand reliability in high-horsepower applications. This casting serves as the foundation for custom LS engine builds, street performance projects, and competition powerplants where stock blocks fall short. Whether you're assembling a naturally aspirated stroker, forced induction platform, or race-ready engine, this aluminum block delivers the strength and precision required for demanding builds.

Constructed from quality aluminum, the block features a 9.240-inch deck height and 4.125-inch bore diameter—critical dimensions that define displacement potential and piston compatibility in LS platforms. The integrated steel main caps provide essential rigidity and crankshaft support, resisting the immense pressures generated by forced induction and high-RPM operation. This combination of lightweight aluminum construction with reinforced steel main bearing saddles optimizes the strength-to-weight ratio, critical for engine bay weight distribution and overall vehicle dynamics. The precision casting ensures proper cylinder wall thickness, coolant passage integrity, and accurate bore geometry for reliable piston ring sealing and minimal blowby.

Engine builders tackling LS engine swaps into vintage Chevrolet, Pontiac, and Buick platforms benefit from this block's compact profile and lightweight design. The 9.240-inch deck height accommodates both LS-family cylinder heads and various stroker crankshaft combinations, making it ideal for displacement increases beyond factory specifications. Proper machine work—deck surfacing, bore honing, and main cap alignment—is essential before assembly to ensure optimal compression ratio, piston clearance, and crankshaft stability. The block's 132-pound weight contributes to favorable front-end weight balance compared to traditional big-block and small-block iron castings.