DSS Racing FX Series Forged Flat Top Piston Set

Fits Most Chrysler / Dodge / Jeep / Ram 6.1L SRT8 Models

1-6840-4125D / 2-6840-4125D / 3-6840-4125D / K1-6840-4125D / K2-6840-4125D / K3-6840-4125D

Overview:

The DSS Racing FX Series Forged Flat Top Piston Set is engineered specifically for high-performance applications in Chrysler, Dodge, Jeep, and Ram vehicles equipped with the 6.1L SRT8 engine. Designed to fit most models featuring a 4.125" bore, these pistons are ideal for enthusiasts and professional builders seeking enhanced durability and precision in their engine builds.

These pistons are crafted to optimize combustion efficiency and withstand the rigors of increased power output, making them a reliable upgrade for street performance, track use, or custom engine projects. Their flat top design and precise specifications ensure improved compression and consistent performance across a variety of setups.

Key Features:

The FX Series pistons incorporate advanced engineering and materials to deliver superior performance and longevity. Key features include:

• Forged construction for maximum strength and durability under high stress
• Flat top design with a -1.5cc volume to optimize compression ratios
• Compatible with 4.125" bore engines, specifically tailored for Chrysler/Dodge/Jeep/Ram 6.1L SRT8 models
• Pin diameter of .927" with options for full-floating or press-fit configurations
• Ring groove dimensions of 1.2mm / 1.2mm / 3mm for reliable ring sealing and reduced blow-by
• Comp height of 1.21" for precise piston-to-deck clearance
• Designed for use with a 3.578" stroke and 6.243" rod length, matching factory and aftermarket builds
• Available in multiple combustion chamber volumes (65cc, 74cc, 85cc) to achieve compression ratios ranging from 9.2:1 to 11.36:1

Construction & Design:

Each piston in the FX Series is forged from high-grade aluminum alloy, providing an excellent balance of lightweight strength and thermal conductivity. The forging process enhances grain structure, resulting in pistons that resist cracking, scuffing, and deformation under extreme operating conditions.

The flat top design reduces quench distance and promotes efficient combustion, which can improve power output and throttle response. The pistons are engineered with precise ring grooves and pin bosses to ensure compatibility with factory and aftermarket components, allowing for flexible installation options.

Installation & Fitment:

These pistons are designed as direct replacements for most Chrysler, Dodge, Jeep, and Ram 6.1L SRT8 engines with a 4.125" bore. Installation requires standard engine assembly procedures, and depending on the pin option selected (full-floating or press-fit), minor adjustments may be necessary. It is recommended to consult with a professional engine builder or mechanic to ensure proper fitment and clearances are maintained.

What's Included:

• Set of forged flat top pistons (quantity as per SKU selection)
• Pin options available: full-floating or press-fit
• Ring groove machining for 1.2/1.2/3mm ring sets

Ideal For:

This piston set is ideal for performance enthusiasts, engine builders, and racers upgrading or rebuilding Chrysler, Dodge, Jeep, or Ram 6.1L SRT8 engines. Whether building a street performance engine, a track-ready powerplant, or a custom Mopar Hemi Gen III 383 small block, these pistons provide the strength and precision needed to handle increased horsepower and torque demands.

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.