With junkyard gold getting harder to pan for, Summit Racing stepped up at the 2025 SEMA Show to solve the engine builder’s block anxiety. Their solution is a new line of robust iron engine blocks dubbed “SPC”—Street, Performance, Competition—designed to handle anything from a daily driver to a high-boost monster. For modern muscle fans, the undeniable star of the lineup is the new iron LS block, built specifically to handle serious horsepower.
This isn’t just another clone. Summit’s team started with Class 35 German iron for a superior base, then poured and machined it right here in the U.S. The LS block combines the best features of Gen III and Gen IV designs into one robust package. It uses the standard 9.240-inch deck height but steps up the game significantly with a 4.125-inch bore and a crucial six-bolt head pattern. This extra clamping force is exactly what you need when planning to shove massive amounts of boost or nitrous into a build, keeping those head gaskets alive under insane cylinder pressure.
Summit Racing’s Justin Weideman noted the block is cleared for big stroker combinations, mentioning 427-cubic-inch builds as a sweet spot. Like all the SPC blocks, it comes with upgraded main cap hardware and a priority-main oiling system to keep bearings happy at high rpm. The blocks ship bored 0.005 inch under, ready for a final hone to match your specific pistons perfectly. Summit isn’t putting a horsepower rating on these blocks. Instead, Weideman issued a challenge: “We can’t wait to see how much power people make out of these things.” With a foundation this solid, the limit is likely your wallet, not the block itself.
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