DSS Racing FX Series Gen III Hemi Forged Piston Set

Fits Most Chrysler / Dodge / Jeep / Ram 6.4L 392 Models

1-6840-4065C / 2-6840-4065C / 3-6840-4065C / K1-6840-4065C / K2-6840-4065C / K3-6840-4065C

Overview:

The DSS Racing FX Series Gen III Hemi Forged Piston Set is engineered specifically for the Chrysler, Dodge, Jeep, and Ram 6.4L 392 engines. Designed for high-performance applications, these pistons provide exceptional strength and durability to withstand the rigors of racing and aggressive street use. Whether you’re building a high-output street machine or a track-ready race engine, this piston set offers reliable performance and precision fitment for the 386 Small Block Mopar Hemi Gen III platform.

With a 4.065" bore size and a compact 1.21" compression height, these forged pistons are optimized for improved combustion efficiency and power delivery. The set is ideal for enthusiasts and professional builders seeking to maximize engine longevity and performance under demanding conditions.

Key Features:

These DSS Racing pistons incorporate advanced design and manufacturing techniques to ensure top-tier performance and reliability:

• Forged construction for superior strength and resistance to high stress
• Flat top piston design with a -1.5cc dish for optimized combustion chamber volume
• Pin diameter of .927" compatible with full-floating or press-fit configurations
• Precision ring grooves sized at 1.2mm / 1.2mm / 3mm for effective sealing and reduced friction
• Compatible with 3.720" stroke crankshafts and 6.2" connecting rods
• Available in multiple combustion chamber volumes (65cc, 74cc, 85cc) to tailor compression ratios
• Approximate compression ratios ranging from 9.28:1 to 11.47:1 depending on chamber size
• Designed specifically for the 386 Small Block Mopar Hemi Gen III platform

Construction & Design:

Each piston in the FX Series is crafted from high-grade forged aluminum alloy, providing an excellent balance of lightweight design and exceptional durability. The forging process enhances the metal’s grain structure, resulting in pistons that resist cracking, scuffing, and thermal fatigue under extreme operating conditions.

The flat top design with a slight dish (-1.5cc) optimizes combustion efficiency and helps manage detonation, while the ring grooves are precision-machined to maintain optimal ring seal and reduce blow-by. The pistons accommodate either full-floating or press-fit wrist pins, offering flexibility for various engine builds and preferences.

Installation & Fitment:

This piston set is engineered for direct fitment in most Chrysler, Dodge, Jeep, and Ram 6.4L 392 Hemi engines, making it an ideal upgrade for performance rebuilds or engine swaps. Installation requires standard machining and assembly procedures consistent with high-performance engine builds. Proper ring end gap and clearance checks are recommended to ensure optimal performance and longevity.

These pistons are compatible with a 4.065" bore and designed to work seamlessly with the 3.720" stroke crankshaft and 6.2" connecting rods typical of the Gen III Hemi platform.

What's Included:

• Set of 8 forged pistons with flat top design
• Precision-machined ring grooves
• Compatible wrist pin options (full-floating or press-fit)
• Technical specifications and installation guidelines

Ideal For:

This piston set is perfect for engine builders, racers, and performance enthusiasts who demand reliable, high-strength components for their 6.4L Hemi builds. Whether upgrading a street performance engine or constructing a race-ready powerplant, these pistons provide the durability and precision needed to handle increased boost, higher RPMs, and aggressive tuning.

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.