There comes a point in a high-horsepower LS build when the factory block becomes the weak link. You can throw bigger turbos, more boost, and increasingly aggressive combinations at an LS, but eventually, you need a foundation that can take the punishment. That’s where the Smeding Performance Aftermarket LS Aluminum 6-Bolt Engine Block comes in.

Built for serious horsepower, this aftermarket aluminum block brings some heavy-duty engineering to the table, including six-bolt cylinder head clamping, billet steel main caps, and an upgraded priority-main oiling system. And with both water-jacketed and solid configurations available, Smeding gives engine builders options for everything from aggressive street-and-strip combinations to dedicated race engines.

Six Bolts Are Better Than Four

When cylinder pressures start climbing, keeping the heads firmly attached becomes a pretty important part of the equation. Smeding’s six-bolt head configuration provides additional clamping force to help prevent head lift and maintain head gasket integrity under extreme conditions.

Down below, four-bolt splayed billet steel main caps with 7/16-inch fasteners add another layer of strength. Combined with the rigid aluminum casting, it’s a bottom end designed to handle the demands of high-output naturally aspirated and boosted engines.

And Smeding didn’t overlook lubrication. Its three-galley priority-main oiling system provides a dedicated oil circuit for the crankshaft and connecting rods, helping maintain consistent oil delivery when RPM and horsepower climb.

Water-Jacketed or Solid? Your Call.

Not every high-performance LS build has the same requirements, and Smeding offers two configurations to match.

The water-jacketed version features conventional coolant passages, making it the practical choice for engines that need to manage heat during sustained operation. For dedicated, short-duration racing applications, the solid version eliminates the water jackets, prioritizing cylinder support where conventional cooling isn’t required.

Both share the same fundamental architecture, including a 9.240-inch deck height, 4.120-inch rough bore, and maximum bore diameter of 4.185 inches. The water-jacketed version comes standard with 7/16-inch head-stud threads, while the solid version uses 1/2-inch threads.