Wiseco 4012P1 HD Pan/Shovelhead 9:1 CR 3.447 In. Bore Forged Piston Kit

The Wiseco 4012P1 is a high-performance forged piston kit engineered specifically for Harley-Davidson Big Twin Panhead and Shovelhead engines. Built to a 3.447-inch (3447X) bore with a 9:1 compression ratio, this kit delivers a proven performance upgrade for classic 74 cubic inch V-Twin builds.

Wiseco is the only aftermarket piston manufacturer in the United States that produces pistons exclusively through the forging process. Starting with high-silicon aerospace-grade aluminum, the forging process compresses and aligns the material's grain structure, producing a piston with superior resistance to impact and fatigue compared to cast alternatives. The result is a lightweight yet exceptionally strong piston optimized for the demands of high-performance V-Twin engines.

Each piston is engineered and machined in-house at Wiseco's Mentor, Ohio facility using 3D design techniques and finite element modeling software to achieve the ideal balance of strength and weight. The optimized piston skirt profile and forging geometry are designed to maximize horsepower, torque, and throttle response.

Kit Includes:

• Forged aluminum domed piston
• Piston rings
• Wrist pin
• Circlips

Key Specifications:

• Bore Size: 3.447 in. (3447X / +.010 over standard)
• Compression Ratio: 9:1
• Piston Style: Large Dome
• Material: Forged high-silicon aluminum alloy
• Top Ring Thickness: 1.58 mm (0.0625 in.)
• 2nd Ring Thickness: 1.58 mm (0.0625 in.)
• Oil Ring Thickness: 4.01 mm (0.158 in.)
• Manufactured in the USA

Important Note: This piston is an oversize (+.010) bore size. Cylinder boring and honing will be required for proper fitment.