LSX Cast Iron Block - 4.185 Bore Finished

The LSX Cast Iron Block - 4.185 Bore Finished is the foundation of legendary high-performance engine builds, trusted by enthusiasts, professional shops, and competitive builders across the country. This bare block serves as the starting point for custom LSX engine assemblies, delivering the durability and precision required for street applications, drag racing, road course competition, and extreme horsepower builds. Built on decades of proven LS-platform engineering, this finished casting eliminates guesswork when constructing a motor tailored to specific performance demands.

Manufactured by Chevrolet Performance to exacting OEM standards, the LSX Cast Iron Block features a 4.185-inch bore diameter, 9.240-inch deck height, and standard main journal sizing with six-bolt main cap design for maximum structural integrity under load. The one-piece rear seal design simplifies gasket management and reduces oil seepage common in older platforms, while the six-bolt head pattern ensures compatibility with modern LS-family cylinder heads. Cast from ductile iron, this block absorbs vibration and thermal stress more effectively than aluminum alternatives, making it the preferred choice for turbocharged, supercharged, and naturally aspirated builds exceeding 600+ horsepower. The finished bore preparation means minimal honing or sizing work before component installation, reducing machine shop time and improving assembly accuracy.

This block is ideal for builders pursuing LS platform performance upgrades, whether constructing a crate engine package, restoring a classic vehicle with modern drivetrain technology, or assembling a dedicated race motor. Compatibility extends across the entire LS family ecosystem—pairing seamlessly with LS1, LS3, LS7, and LSX cylinder heads, as well as aftermarket intake manifolds, fuel systems, and ignition components. The 268-pound weight and compact dimensions (19.75 x 19.5 x 24.75 inches) make handling and engine bay fitment straightforward for most applications. Installation requires professional machine work and assembly expertise; consult a qualified engine builder or performance shop to ensure proper honing, bore sizing, and component selection for your intended power level and fuel type.