JE Pistons Ultra Series GM Gen III/IV LS 4.005in Bore/3.622in Stroke Set of 8 Pistons

When you're building a serious GM Gen III/IV LS engine, especially one that's going to see boost or nitrous, you need pistons that can handle the pressure. This set of eight Ultra Series pistons from JE Pistons is built for exactly that. You get the pistons themselves, designed to fit a 4.005-inch bore with a 3.622-inch stroke, along with high-strength wrist pins from Trend Performance, all made right here in the USA.

What sets these Ultra Series pistons apart is JE's proprietary Aligned Grain Flow forging technology. This process maximizes the material's tensile strength, giving these pistons the backbone needed to withstand the extreme cylinder pressures found in boosted or nitrous-fed V8s. They also come with custom-level features you'd normally only find on a full custom build. The thermal barrier crown coating helps reflect heat back into the combustion chamber, which can improve scavenging and keep crown temperatures down. On the skirts, a special coating reduces friction and wear against the cylinder walls, also helping to quiet things down, especially during a cold start. Plus, lateral gas ports are included to help maintain a solid seal on the top compression ring, even when you're pushing high RPMs and significant boost.

These pistons are engineered for high-horsepower racing engines, and every feature is optimized for that purpose. Keep in mind that these are not CARB approved and cannot be shipped to California. For a robust LS engine build that needs pistons ready for serious power, this set is a well-built option.