ARP Ring Compressor

3.700–3.937˝ (94–100mm) Ring Square Tool

Part #: 902-9400

Overview

The ARP Ring Compressor is a precision-engineered tool designed to assist automotive enthusiasts and professional mechanics in accurately fitting piston rings during engine assembly. Crafted by ARP, a trusted name in high-performance fasteners and engine components, this ring compressor ensures a secure and proper seal between the piston and cylinder wall, which is critical for optimal engine performance and longevity. Whether you're rebuilding an engine for street use, performance upgrades, or racing applications, this tool helps streamline the assembly process, reducing the risk of ring damage or improper installation.

Constructed from high-quality materials and featuring dual-sized bore options, the ARP Ring Compressor is suitable for a wide range of piston sizes. Its durable design and precise machining make it an essential addition to any engine builder's toolkit, providing confidence in achieving a perfect fit every time. This tool is ideal for both professional engine builders and serious DIY enthusiasts aiming for professional-grade results.

Key Features

The ARP Ring Compressor offers several advanced features that enhance its functionality and durability:

• Manufactured from CNC-machined 6061 T-6 billet aluminum, providing excellent strength-to-weight ratio and resistance to corrosion.
• Black anodized finish not only offers a brilliant, professional appearance but also adds a layer of protection against wear and environmental elements.
• Dual bore sizes range from 3.700 to 3.937 inches (94 to 100mm), accommodating a variety of piston diameters for different engine builds.
• Engraved bore sizes ensure easy identification and quick adjustments during assembly, saving time and reducing errors.
• Precision CNC machining guarantees a smooth, accurate bore surface, minimizing the risk of damaging piston rings during installation.
• Designed for ease of use with a secure fit around the piston, ensuring even compression and preventing ring distortion.
• Compatible with both SAE and metric piston sizes, making it versatile for various engine types and specifications.
• Built to withstand the rigors of professional engine assembly, ensuring long-lasting performance and reliability.
• Helps support consistent ring seating, which is vital for optimal compression, power output, and engine efficiency.

Construction & Design

The ARP Ring Compressor is meticulously crafted from high-grade 6061 T-6 billet aluminum, a material renowned for its strength, durability, and lightweight properties. The CNC-machined construction ensures precise bore dimensions and a smooth surface finish, which is essential for preventing damage to piston rings during installation. The black anodized coating not only enhances the tool's appearance but also provides excellent corrosion resistance, ensuring it remains in top condition through multiple uses.

The dual-sized bore design allows for flexibility, accommodating piston diameters from 3.700 to 3.937 inches (94–100mm). The engraved size markings facilitate quick identification and adjustment, streamlining the assembly process. The tool's design ensures a secure fit around the piston, distributing compression evenly and reducing the risk of ring distortion or damage. Its lightweight yet robust construction makes it easy to handle and position during engine assembly, whether in a professional shop or a home garage.

Performance & Use

While primarily a tool for assembly rather than performance enhancement, the ARP Ring Compressor plays a crucial role in ensuring the longevity and efficiency of your engine. Proper ring installation supported by this tool helps achieve optimal compression, which directly impacts engine power, fuel efficiency, and emissions. Its precise fitment reduces the likelihood of ring scuffing or uneven seating, contributing to a more reliable and durable engine build.

Installation & Fitment

The ARP Ring Compressor is designed for straightforward, bolt-on use. Simply select the appropriate bore size, position the compressor around the piston and ring, and gently compress the ring into the cylinder bore. The tool's snug fit ensures even pressure distribution, making ring installation easier and safer. No additional tools, cutting, or modifications are required, making it suitable for both professional assembly lines and DIY rebuilds.

• Easy to use with a secure fit around the piston
• No cutting, drilling, or special tuning needed
• Designed for quick and accurate piston ring installation

What's Included

• ARP Ring Compressor (902-9400) with dual-sized bore options
• Engraved size markings for quick identification
• Durable CNC-machined billet aluminum construction

Ideal For

• Engine rebuilds and restorations
• Performance and racing engine assembly
• DIY enthusiasts and professional engine builders
• Applications requiring piston diameters from 3.700 to 3.937 inches (94–100mm)

Emissions Note

This product is a specialized tool intended solely for engine assembly and repair. It does not impact emissions or legal compliance. Always ensure proper installation procedures and local regulations when working on engines.