DSS Racing FX Series +4cc Dome Top Forged Piston Set

Chrysler / Dodge / Jeep / Ram 6.4L 392 Gen III Hemi Engines

1-6847-4085C / 2-6847-4085C / 3-6847-4085C / K1-6847-4085C / K2-6847-4085C / K3-6847-4085C

Overview:

The DSS Racing FX Series +4cc Dome Top Forged Piston Set is engineered specifically for Chrysler, Dodge, Jeep, and Ram 6.4L 392 Gen III Hemi engines. Designed to enhance performance and durability, these pistons are ideal for enthusiasts and professional builders seeking reliable, high-quality components for their small block Mopar Hemi builds. Featuring a +4cc dome top design, these pistons help optimize compression ratios for improved combustion efficiency and power delivery.

Whether you are upgrading your engine for street performance, racing, or heavy-duty applications, the DSS Racing FX Series pistons offer a precise fit and robust construction to withstand demanding conditions.

Key Features:

These forged pistons incorporate advanced design elements to maximize engine performance and longevity:

• Compatible with 6.4L 392 Gen III Hemi engines from Chrysler, Dodge, Jeep, and Ram
• +4cc dome top design to increase compression and improve power output
• Comp height of 1.21 inches for optimal piston-to-head clearance
• Pin diameter of .927 inches, available in full-floating or press-fit configurations
• Ring groove dimensions: 1.2mm top and second rings, 3mm oil ring for effective sealing
• Stroke length of 3.720 inches matched with a 6.2-inch connecting rod for balanced performance
• Available in multiple compression ratios to suit different combustion chamber volumes: 65cc (12.47:1), 74cc (11.16:1), and 85cc (9.91:1)
• Designed for 390 Small Block Mopar Hemi Gen III applications

Construction & Design:

Each piston in the DSS Racing FX Series is forged from premium-grade aluminum alloy, providing exceptional strength-to-weight ratio and thermal conductivity. The dome top shape is precision-machined to exact specifications, ensuring consistent combustion chamber volume and reliable compression ratios. The pistons feature carefully engineered ring grooves to accommodate high-performance piston rings, enhancing sealing and reducing blow-by.

The pin bore is designed to accept either full-floating or press-fit wrist pins, allowing flexibility based on engine build preferences. The combination of a 3.720-inch stroke and 6.2-inch connecting rods ensures optimal piston speed and mechanical efficiency within the 6.4L 392 Hemi platform.

Installation & Fitment:

These pistons are direct replacements for the 6.4L 392 Gen III Hemi engines found in Chrysler, Dodge, Jeep, and Ram vehicles. Installation requires standard engine assembly procedures and may necessitate matching the piston compression height to the cylinder head combustion chamber volume to achieve the desired compression ratio. No major modifications are typically needed when upgrading from factory pistons, but professional installation is recommended to ensure proper ring end gap and piston-to-wall clearance.

What's Included:

• Set of forged +4cc dome top pistons (quantity as required for engine configuration)
• Wrist pin options: full-floating or press-fit (depending on selected SKU)
• Detailed specifications for ring groove dimensions and piston geometry

Ideal For:

This piston set is ideal for performance enthusiasts, engine builders, and racers upgrading or rebuilding Chrysler, Dodge, Jeep, or Ram 6.4L 392 Gen III Hemi engines. It suits applications ranging from street performance to competitive racing where increased compression and durability are critical. The multiple compression ratio options allow customization to match fuel type, tuning, and intended use.

DSS Racing — Founded in 1983 originally as Danny’s Speed Shop, DSS Racing has grown from a small Midwest performance engine shop into a respected name in forged engine components for the high-performance and racing markets. Based in St. Charles, Illinois, DSS is best known for its forged pistons and machined engine parts made in the USA that have been used in championship engines and thousands of builds, blending old-school racing roots with precision manufacturing for enthusiasts and racers alike.