ARP 900-0550 PISTON RING COMPRESSOR 4.055" BORE FOR 2001–2016 GM 6.6 DURAMAX ENGINE

FAST, DAMAGE-FREE DURAMAX PISTON INSTALLS. The ARP 900-0550 tapered piston ring compressor is CNC-machined from billet 6061-T6 aluminum and anodized for long life. Sized precisely for a 4.055" bore, it streamlines assembly on 2001–2016 GM 6.6L Duramax (LB7/LLY/LBZ/LMM/LML) and any engine built to a true 4.055" cylinder. The taper guides the piston smoothly while compressing rings evenly to protect ring lands and coatings.

• Application-specific taper for a perfect start and smooth entry.
• Billet 6061-T6 tube with Type 3 hard anodize for durability.
• Relieved to accommodate wire O-rings at the deck.
• Designed by ARP for professional engine builders and DIY pros.

Fitment

• 2001–2016 GM 6.6L Duramax (LB7, LLY, LBZ, LMM, LML) – standard 4.055" bore
• Also fits any engine with a measured 4.055" bore (confirm block & piston size prior to use).

Cross Reference & Related ARP Tools

• ARP 900-0750 – 4.075" Bore (.020 Over) Ring Compressor
• ARP 900-1300 – 4.130" Bore Ring Compressor (Ford 7.3L)
• ARP 899-7400 – 3.740" Bore Ring Compressor (Ford 6.0L)
• ARP 900-2125 – 4.2125" Bore Ring Compressor (Cummins 6.7L)
• ARP 100-9909 – Ultra-Torque® Assembly Lubricant
• ARP 230-4201 – Duramax Head Stud Kit (ARP2000)
• Shop All ARP at CPP Diesel

FAQ

WHAT BORE SIZE DOES ARP 900-0550 FIT?
4.055" true bore (standard Duramax 6.6L). Measure your block and piston size before ordering.

CAN I USE THIS ON AN OVERBORE DURAMAX?
Use the matching overbore tool like ARP 900-0750 for .020" over (4.075").

DO I NEED SPECIAL LUBE OR SETUP?
Light oil on the skirt/rings and a clean, chamfered bore. For fastener work during the build, use ARP Ultra-Torque® Assembly Lube.

WILL THIS SCRATCH COATED RINGS?
The tapered, smooth inner surface is designed to protect ring coatings when used correctly.

Specifications for ARP 900-0550

Always verify bore size and piston dimensions before use. Professional installation recommended.