SKU: GMP12729604
MPN: 12729604
The CHEVROLET PERFORMANCE LS3/L92 Engine Block is the bare aluminum foundation for a Gen 4 small-block build, sold under part number 12729604. It's aimed at builders putting together a street or race 6.2L from the ground up, or anyone replacing a cracked or worn core. The block uses an aluminum alloy casting with pressed-in iron sleeves, a 4.065 in. bore, and a 9.240 in. deck height. It's a direct replacement for several factory engines, including the 2008-2013 LS3, the 2007-2008 L92, the 2010-2013 L99, the 2010-2012 L94, and the 2009-2012 L9H. Buyers start here when they want a proven block they can machine and assemble to spec.
The casting runs a deep-skirt design that extends below the crankshaft centerline, which adds rigidity where the bottom end takes the most load. Forged powdered-metal six-bolt main caps with cross-bolting hold the crank, and the block carries the production oiling system along with provisions for cylinder deactivation. The 4.065 in. bore and standard deck accept LS1, LS6, LS2, and L92/LS3-style cylinder heads, so head selection stays flexible across most of the LS family. It's been tested past 500 horsepower and supports stroker cranks up to a 4.00 in. stroke for builders chasing bigger displacement. Pair it with the right main bearing set and an LS oil pan when you spec the bottom end.
A builder reaches for this block when starting a fresh 6.2L for a swap, a hot rod, or a closed-course race car, or when an existing core is past saving. Because it's bare, you supply the rotating assembly, heads, oiling components, and camshaft to finish it. It's legal for use only on uncontrolled vehicles or vehicles used solely for closed competition, so plan the build accordingly. When you're ready to round out the assembly, browse our full lineup of engine components and the LS camshafts in our cam selection to match your power target.
It's a direct replacement for the 2008-2013 LS3, 2007-2008 L92, 2010-2013 L99, 2010-2012 L94, and 2009-2012 L9H. The casting carries the production oiling system and provisions for cylinder deactivation, so it drops into most Gen 4 6.2L builds using factory architecture.
The block has been tested past 500 horsepower and is built around a deep-skirt casting with forged powdered-metal six-bolt cross-bolted main caps. That bottom-end rigidity is why it holds up in both street and race applications well above stock output levels.
The bore measures 4.065 in. (103.25mm) and the deck height is 9.240 in. It supports stroker cranks up to a 4.00 in. stroke, giving builders room to increase displacement past the factory 6.2L.
It's a bare block. You supply the crankshaft, rods, pistons, cylinder heads, camshaft, oiling components, and gaskets. It accepts LS1, LS6, LS2, and L92/LS3-style heads, which keeps your head and cam choices open across the LS family.
It's legal for sale and use only on uncontrolled (non-emissions-controlled) vehicles or vehicles used solely for closed competition racing. Confirm your intended use matches those terms before building.
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