Big-inch and high-horsepower LS builds are as American as the smell of race gas and tire smoke. But the cost to build one has gone up significantly over the years with the increase in parts cost and good quality machine shop labor prices. Thankfully, we can always count on the aftermarket delivering solutions for quality parts that can still achieve our ever-lofty power goals. Summit Racing did just that with their all-new iron SPC Pro LS Blocks.

All New With Better Tech

The performance-aftermarket mail-order giant released their latest block just a few weeks ago and the specs listed are certain to raise the eyebrows of those seeking lofty power goals. Instead of saving a few bucks to cast the block out of basic gray iron, Summit has teamed up with a Tier 1 foundry in Germany that also cast OEM blocks for other manufacturers to cast their block out of a class 35 iron alloy that is harder with a higher tensile strength than the competition. The blocks are then sent to the US for final machining to Summit’s set tolerances.

Summit took the best learned from the Gen III blocks, Gen IV blocks, and racing to give the Summit LS block every advantage possible. Starting at the bottom, the SPC Pro LS block features the same six-bolt main cap design as the Gen III and Gen IV OEM blocks, but with billet steel caps and 180,000 PSI main bolts for extra strength.

The current bore size offered is 4.125 inches, the same as the 7.0-liter LS7, with a 4.065-inch bore available soon. But the cylinder walls are thicker and longer than stock for extra strength. Stock cylinder length is 5.500 inches with the Summit LS block measuring 5.750 inches. A tall-deck version will be released soon that features a 9.705-inch deck height versus the standard 9.240-inch height, which will also feature a longer cylinder measuring 6.200 inches to handle extra big.

Summit knows how much the LS community loves to throw a stroker kit in any LS block they can get their hands on, from turning 4.8s into 383s to LS7s turning out 440 cubic-inches. So they designed notches cast into the bottom of the cylinder to handle a 4.000-inch stroke without extra machine work. With the tall deck you can get 4.250 inches of stroke to really maximize displacement. The deck is thicker than OEM as well for more reliable head gasket retention and will come in either four or six-bolt-per-cylinder-head patterns.

Big Cubes, Big Power, Or Both

These features add up to make this block more capable of tackling a big-inch LS over the OEM blocks and handling the extra power that comes with it. While Summit does not state any specific power level, we would not be surprised to see these blocks handle 2,000-plus horsepower with ease when paired with a couple of properly-sized turbos. You can also utilize the max bore and stroke the Summit LS block can handle to get a 468-cubic-inch LS. That is approximately 7.7 liters of naturally-aspirated grunt you could potentially have under the hood of your next project.