Wiseco S721 9310 Steel Wrist Pin 0.827 in. Diameter x 2.36 in. Length

The Wiseco S721 is a 9310 steel wrist pin measuring 0.827 in. (21mm) in outer diameter and 2.360 in. (60mm) in length, weighing 128 grams. Designed for high-demand performance applications, this wrist pin is engineered to handle the extreme forces generated inside a high-output engine. It is compatible with the CW28 wire lock retainer and is sold individually.

Wiseco piston wrist pins are available in three material grades, each engineered for a specific performance level. The S721 uses the premium 9310 material — the top-tier choice for forced induction and power-adder applications.

9310 Material Pin (S721):

• High-quality, low-carbon case-hardened steel
• Case hardened to 59–63 Rockwell C
• Ground to a superfinish of .025 Ra or better
• Engineered for applications requiring high surface strength combined with high core toughness
• Ideal for high contact stress combined with shock and impact loading — including turbo and nitrous applications

Wiseco Wrist Pin Material Comparison:

• 5115 Material: Standard chromium alloy steel, case hardened to 58–64 Rockwell C, ground to .15 Ra or better — for normal aftermarket engine wear
• 52100 Material: High-carbon, chromium-bearing aircraft-quality alloy, case hardened to 54–56 Rockwell C — for high load capacity and outstanding abrasion resistance
• 9310 Material (this pin): Premium low-carbon case-hardened steel, case hardened to 59–63 Rockwell C, superfinished to .025 Ra — for turbo, nitrous, and maximum-stress applications

The Wiseco S721 wrist pin is a direct-fit solution for builders seeking a reliable, performance-grade wrist pin for high-output and power-adder engine builds. Use with CW28 wire lock retainer clips.