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

If you're building a high-horsepower GM Gen III or IV LS engine, especially one that will see boost or nitrous, JE Pistons' Ultra Series forged pistons are a solid choice. These aren't your average off-the-shelf pistons; they're packed with features typically found only on custom sets, all designed to handle the extreme cylinder pressures that come with serious power adders. They're made 100% in the USA, which is always a good sign of quality control.

What really sets these Ultra Series pistons apart is JE's proprietary Aligned Grain Flow forging technology. This process maximizes the tensile strength of the aluminum, making them incredibly strong and able to withstand the immense stresses of boosted or nitrous-fed V8s. You also get a thermal barrier crown coating, which is a ceramic-based layer that reflects heat back into the combustion chamber. This helps keep piston crown temperatures down and can improve how efficiently exhaust gases are scavenged. The pistons also come with a skirt coating to reduce friction and wear on the cylinder walls, which not only helps with longevity but also quiets down operation, especially when the engine is cold. Plus, they feature lateral gas ports to help maintain a tight seal on the top compression ring, even under high RPM and boost conditions, ensuring consistent power delivery.

This set is specifically designed for a 4.000-inch bore and a 4.000-inch stroke, with a flat-top design and a -5.00cc dish, and includes high-strength wrist pins from Trend Performance. Keep in mind these pistons are not CARB approved and cannot be shipped to California. If you're aiming for serious power and need pistons that can handle it, this set is built for that purpose.