JE Pistons Ultra Series GM Gen III/IV LS 4.135in Bore/4in Stroke Set of 8 Pistons

If you're building a high-horsepower GM Gen III or IV LS engine, especially one that's going to see boost or nitrous, you need pistons that can handle the extreme cylinder pressures. The JE Pistons Ultra Series are designed precisely for those demanding applications. These aren't just off-the-shelf pistons; they incorporate custom-level features that set them apart for serious performance builds.

What makes these Ultra Series pistons so strong is JE's proprietary Aligned Grain Flow forging technology. This in-house process maximizes the tensile strength of the aluminum, allowing them to withstand the immense forces generated in boosted and nitrous-fed V8s. You'll also find a thermal barrier crown coating, which is a ceramic-based material that reflects heat back into the combustion chamber, helping to keep piston crown temperatures down and improving how efficiently exhaust gases are scavenged. For reduced friction and wear on the skirts and cylinder walls, a skirt coating is applied, which also helps quiet down operation, especially when the engine is cold. Plus, they feature lateral gas ports to help maintain a solid ring seal even at high RPMs and under heavy boost.

This set includes eight pistons, each with a 4.135-inch bore and designed for a 4-inch stroke. They also come with high-strength, thick-wall wrist pins manufactured by Trend Performance. Every feature on these pistons is optimized for high-horsepower racing engines, and they are proudly made 100% in the USA. Keep in mind these pistons are not CARB approved and cannot be shipped to California.