4.115" Bore Ring Compressor

Features:

• Fits 4.115 inch bore engines
• CNC-machined from 6061-T6 billet aluminum
• True radius design for superior ring seating
• Preferred by professional engine builders
• Relieved bottom for wire O-ring clearance
• Type 3 anodized for maximum durability
• Engraved bore size for quick identification
• Designed for precision and repeatable results
• Reduces risk of ring damage during install
• Ideal for high-performance engine assemblies
• Resists wear from repeated engine builds
• Trusted ARP quality and craftsmanship

Make Your Engine Build Smoother From The Start

If you've ever fought with a ring compressor mid-build, you know how much time and frustration it can add to the process. The ARP 900-1150 4.115 Bore Ring Compressor is built to take that hassle off your plate and replace it with confidence. Whether you're rebuilding a 6.6L Duramax from the ground up or dialing in a performance engine for your next project, this tool gives you the kind of precision and ease you need to do the job right. The true radius design means your piston rings glide in smoothly without hang-ups or stress, cutting down the risk of breakage and helping you maintain perfect tolerances. This isn’t a tool that just gets the job done, it makes the process feel professional and controlled. It's a favorite among engine builders who value reliability and repeatability during assembly. Plus, it's made by ARP, a brand trusted across the performance world for building tools that actually hold up. If you're aiming to do things the right way the first time, this compressor is a must-have.

Precision Matters Most When Tolerances Are Tight

Engine assembly is all about precision, and the ARP 900-1150 ring compressor is designed with that exact mindset. CNC-machined from high-strength 6061-T6 billet aluminum, this tool delivers a perfect 4.115 inch bore fit that’s critical when building high-performance engines. Unlike standard tapered tools, this unit features a true radius design that provides consistent pressure around the piston for safer and smoother ring installation. It also includes a bottom relief to accommodate wire O-rings, helping ensure your piston lands square and clean without snagging or damage. The bore size is clearly engraved in large 3/4-inch numbers, so there’s no second-guessing your setup during a fast-paced build. Type 3 hard anodizing adds another layer of protection, keeping the surface clean and intact even after multiple uses in harsh shop environments. Whether you’re assembling a race motor or restoring a daily workhorse, this compressor ensures every piston goes in with precision and care. It’s engineered for builders who expect professional-grade results from every component on their bench.

Fits: 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Notes:

• Designed for 4.115 inch bore engines
• Ideal for 2001-2016 GM Duramax 6.6L applications
• Features a true radius design for smoother installs
• Preferred by professional engine builders for reliability
• Not compatible with tapered-style ring compressors
• Includes bottom relief for wire O-ring clearance
• Made from 6061-T6 billet aluminum for strength
• Type 3 anodized finish for wear and corrosion resistance
• Engraved bore size for quick and easy identification
• Not returnable if factory packaging is opened