The new Smeding Performance Heavy-Duty 6-Bolt LS Engine Block is engineered for racers who demand a stronger, more capable foundation for today’s high-performance LS builds. Designed to withstand the extreme cylinder pressures and RPM levels common in modern race applications, this aftermarket block delivers the strength and oiling efficiency needed when a production block simply isn’t enough.

Cast from 220 BHN Class 35 gray cast iron, the block provides exceptional strength, rigidity, and durability. A set of billet steel main caps comes standard, utilizing a 4-bolt splayed main cap design with 7/16-inch fasteners for increased bottom-end stability and clamping strength.

The cylinder heads are secured with an upgraded 6-bolt head bolt configuration, providing additional clamping force to help maintain head gasket integrity under extreme cylinder pressures. This makes the block an ideal foundation for high-output naturally aspirated, boosted, and other demanding race applications.

The oiling system has also been significantly upgraded with a three-galley oiling design. This configuration provides the crankshaft and connecting rods with a dedicated oil circuit, improving oil distribution and reducing the demands placed on the main oiling system. The result is a more efficient and robust lubrication system designed to support the extreme RPM levels found in today’s high-performance race engines.

For additional customization and strength, the Smeding Performance Heavy-Duty 6-Bolt block is available with 1/2-inch head bolt machining and an ARP main stud upgrade.

When the goal is to build a serious LS engine capable of handling increased power, cylinder pressure, and RPM, the Smeding Performance Heavy-Duty 6-Bolt Cast Iron Engine Block provides the foundation to do it right.

Specs:
Shipped Bore Diameter - 4.120" 
Maximum Bore Diameter - 4.185"
Deck Height - 9.240"
Cylinder Length - 5.750"
Engine Block Material - 220 BHN Class 35 Gray Cast Iron
Main Cap Material - Billet Steel
Main Cap Fasteners - 7/16" SP8740 Alloy
Oiling System - Priority Main 3-Galley
Lifter Bore - 0.842"
Thrust Plate Included
Block Plug Kit Included

Compatible Parts:
Head Stud Kit - ARP 234-4341
Main Stud Kit - ARP 134-5901
Cam Bearings - Dura-Bond 32210101T
Main Bearings - King MB5777XP
Rear Main Seal - GM 12639250