Wiseco K0145A3940 Forged Piston Kit SB Mopar 318/340/360 -18cc Reverse Dome 3.940 Bore Stroker

The Wiseco K0145A3940 is a Professional Series forged piston kit designed for Chrysler Small Block 318, 340, and 360 stroker engine builds. Featuring a -18cc reverse dome design and a 3.940-inch bore, these pistons are purpose-built for the 4.000-inch stroker configuration, delivering tunable compression ratios to suit a wide range of performance and racing applications.

Forged from 2618 high-strength aerospace alloy, these pistons offer superior tensile strength and heat resistance compared to budget cast or hypereutectic alternatives, making them well-suited for high-cylinder-pressure builds including naturally aspirated, nitrous, turbocharged, and supercharged combinations.

Key Features:

• Bore: 3.940 in.
• Compression Height: 1.460 in.
• Stroke: 4.000 in. (Stroker Kit)
• Rod Length: 6.123 in.
• Dome Volume: -18cc (Reverse Dome)
• Average Piston Weight: 490 g
• Wrist Pin: S547 .984 x 2.500 in. (included)
• Skirt Type: Slab Sided with ArmorGlide® coating
• Ring Grooves: 1/16, 1/16, 3/16 — rings sold separately (3940H x 8)
• Anti-detonation and pressure seal grooves
• 0 Deck Height: 9.585 in. | Standard Deck Height: 9.600 in.

Compression Ratios (with .040 head gasket):

• 58cc combustion chamber: 10.4:1
• 62cc combustion chamber: 10.0:1
• 66cc combustion chamber: 9.6:1
• 72cc combustion chamber: 9.1:1

ArmorGlide® Skirt Coating is applied to the piston skirts to reduce friction, improve wear resistance, and allow tighter bore fitment than non-coated pistons — resulting in reduced piston rock, quieter operation, and improved ring seal. Note: This is a build-on-demand product. Matching ring set (part# 3940H) is sold separately.