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

Chrysler / Dodge / Jeep / Ram 6.4L 392 Models

1-6837-4125 / 2-6837-4125 / 3-6837-4125 / K1-6837-4125 / K2-6837-4125 / K3-6837-4125

Overview:

The DSS Racing FX Series +4cc Dome Top Forged Piston Set is engineered specifically for the 6.4L 392 HEMI engines found in Chrysler, Dodge, Jeep, and Ram vehicles. Designed to enhance performance and durability, these pistons are an ideal upgrade for enthusiasts seeking improved combustion efficiency and reliability under high-stress conditions. Whether you are building a high-performance street machine or a track-focused build, these pistons deliver consistent power gains and long-lasting strength.

With a 4.125" bore size and a +4cc dome top design, these pistons increase compression ratios while maintaining optimal combustion chamber dynamics. They are compatible with the 398 Small Block Mopar HEMI Gen III platform and feature a compact 1.21" compression height, making them a direct fit for most 6.4L 392 applications.

Key Features:

Built for precision and performance, the DSS Racing FX Series pistons offer the following key features:

• +4cc dome top design to increase compression and improve power output
• Forged construction for superior strength and durability under high RPM and boost
• 1.21" compression height optimized for 6.4L 392 HEMI engines
• .945" pin diameter with options for full-floating or press-fit configurations
• Ring groove dimensions of 1.2mm / 1.2mm / 3mm for reliable ring sealing and reduced friction
• Compatible with a 3.720" stroke and 6.2" connecting rods for precise fitment
• Available in multiple combustion chamber volume options (65cc, 74cc, 85cc) to tailor compression ratios from approximately 12.68:1 to 10.08:1
• Designed to withstand the rigors of high-performance and racing environments

Construction & Design:

These pistons are crafted from high-grade forged aluminum alloy, providing an excellent balance of lightweight strength and thermal conductivity. The forging process enhances grain structure and mechanical properties, ensuring resistance to cracking and deformation under extreme heat and pressure. The dome top shape is precisely machined to optimize combustion chamber shape and improve flame propagation, resulting in better efficiency and power delivery.

The pistons feature a robust pin boss design with a .945" wrist pin diameter, available in both full-floating and press-fit options to suit different engine builds and preferences. The ring grooves are engineered to accommodate performance ring sets, maintaining a tight seal while minimizing friction and wear.

Installation & Fitment:

This piston set is designed as a direct replacement for most Chrysler, Dodge, Jeep, and Ram 6.4L 392 HEMI engines, requiring no major modifications for installation. The compact 1.21" compression height and precise bore sizing ensure compatibility with stock and aftermarket components. Installation should be performed by a professional engine builder or experienced technician to ensure proper ring end gap, piston orientation, and clearances are maintained for optimal performance and longevity.

What's Included:

• Set of forged +4cc dome top pistons (quantity as per engine requirements)
• Wrist pins (.945" diameter), full-floating or press-fit depending on selected option
• Detailed specifications for ring groove dimensions and compression height

Ideal For:

This piston set is ideal for performance enthusiasts, engine builders, and racers upgrading or rebuilding 6.4L 392 HEMI engines. It suits applications ranging from street performance to competitive motorsports where increased compression and durability are critical. Whether upgrading a factory engine or building a custom high-output powerplant, these pistons provide a reliable foundation for enhanced horsepower and torque.

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.