DSS Racing FX Series Forged Piston Set

Fits Chrysler, Dodge, Jeep, Ram 6.4L 392 Models

1-6837-4090 / 2-6837-4090 / 3-6837-4090 / K1-6837-4090 / K2-6837-4090 / K3-6837-4090

Overview:

The DSS Racing FX Series +4cc Dome Top Forged Piston Set is engineered specifically for high-performance applications in Chrysler, Dodge, Jeep, and Ram 6.4L 392 engines. Designed to fit most 6.4L 392 HEMI models, these pistons provide a reliable upgrade for enthusiasts seeking enhanced durability and improved combustion efficiency. With a 4.090" bore size and a +4cc dome top design, this piston set offers increased compression ratios and optimized power delivery.

Ideal for builders and racers who demand precision and strength, these pistons support aggressive tuning and higher boost levels while maintaining engine reliability. Whether you are rebuilding your 6.4L HEMI or upgrading for performance gains, the DSS Racing FX Series pistons deliver consistent quality and performance.

Key Features:

These forged pistons incorporate advanced engineering to meet the demands of modern high-output Mopar engines. Key features include:

• +4cc dome top design for increased compression and improved combustion
• Compatible with 4.090" bore size, fitting most Chrysler/Dodge/Jeep/Ram 6.4L 392 engines
• Forged construction for superior strength and durability under high stress
• Pin diameter of .945" with options for full-floating or press-fit configurations
• Ring groove dimensions of 1.2mm top and second rings, 3mm oil ring for optimal sealing
• Comp height of 1.21" to maintain proper piston-to-head clearance
• Designed for 3.720" stroke and 6.2" rod length applications
• Available in multiple combustion chamber volumes (65cc, 74cc, 85cc) to tailor compression ratios
• Approximate compression ratios ranging from 9.94:1 to 12.5:1 depending on chamber size

Construction & Design:

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

The dome top design increases the combustion chamber volume by +4cc, which helps optimize the compression ratio for improved power output and throttle response. Precision machining ensures tight tolerances for a perfect fit in the cylinder bore, while the ring grooves are engineered to accommodate high-performance piston rings for superior sealing and oil control.

Installation & Fitment:

This piston set is designed as a direct fit for most Chrysler, Dodge, Jeep, and Ram 6.4L 392 HEMI engines with a 4.090" bore. Installation requires standard engine rebuilding procedures, including proper honing and cleaning of the cylinder bores. Depending on your build, you can choose between full-floating or press-fit wrist pins to match your connecting rods and performance goals.

Due to the +4cc dome volume and specific comp height, it is important to verify piston-to-valve clearance and deck height during assembly. Professional installation is recommended to ensure optimal performance and longevity.

What’s Included

• Set of forged aluminum pistons (quantity as per engine requirements)
• Wrist pins (.945" diameter), available in full-floating or press-fit options
• Precision-machined piston rings (1.2mm top and second rings, 3mm oil ring)
• Installation instructions and technical specifications

Ideal For:

This piston set is perfect for performance enthusiasts, engine builders, and racers upgrading or rebuilding their 6.4L 392 HEMI engines. Whether you are aiming for increased horsepower, improved throttle response, or enhanced engine durability under high-stress conditions, the DSS Racing FX Series pistons provide a reliable foundation for your build.

They are especially suited for naturally aspirated, supercharged, or turbocharged applications where strength and precision are critical.

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.