JE Pistons Ultra Series GM Gen III/IV LS 4.01in Bore/4in Stroke Set of 8 Pistons

When you're building a serious GM Gen III or 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 4.010-inch bore with a 4-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 piston's tensile strength, making it incredibly tough for those high-stress engine builds. They also come with a bunch of custom-level features you don't often see on off-the-shelf parts. The thermal barrier crown coating helps reflect heat back into the combustion chamber, keeping piston crown temperatures down and improving how the exhaust gases get scavenged. On the sides, the skirt coating works to reduce friction and wear on both the piston skirts and cylinder walls, which also helps quiet things down, especially when the engine is cold. Plus, they've got lateral gas ports to help maintain a solid ring seal even at high RPMs and under heavy boost, ensuring you keep making power.

These pistons are optimized for high-horsepower racing engines, and every feature is geared towards performance. The enhanced pin oiling system keeps the pin, bores, and small end well-lubricated, reducing heat and wear. Keep in mind these are not CARB approved and cannot be shipped to California. If you're aiming for a powerful LS engine build, these pistons are a solid choice to form the foundation.