Cummins QSB 6.7 Marine Engine Guide

Cummins QSB 6.7 Marine

Common Rail Performance Meets Legendary Reliability

Cummins 6BTA 5.9 Marine Engine

The Next Generation: Quantum Series Performance

The Cummins QSB 6.7 (Quantum System Board) took the industry by storm as the successor to the 5.9L. Built on the same "B-Series" foundation, it features a 24-valve cylinder head and a Bosch High-Pressure Common Rail (HPCR) fuel system. This technology eliminates the "cold-start smoke" associated with older diesels and provides a flatter torque curve for better hole-shots. At Choate Performance, we remanufacture these electronic powerhouses to meet Tier 3 standards while ensuring the cooling and fuel systems are ready for the rigors of modern yachting.

6.7 LitersDisplacement
107mm x 124mmBore & Stroke
HPCRHigh Pressure Common Rail
SmartCraftDigital Electronics

Performance Ratings Table

The QSB 6.7 is available in a wide range of ratings to suit everything from displacement trawlers to high-speed interceptors.

Horsepower Rating Aspiration Duty Cycle Common Application
230 - 250 HP Turbocharged Continuous Tugs / Displacement Trawlers
380 - 425 HP Aftercooled Intermittent Charter Fishing / Cruisers
480 HP Aftercooled Government / Recreational Mid-sized Yachts / Patrol Boats
550 HP Aftercooled High Output Sportfish / High-Speed Tenders

Common Vessel Applications

The QSB 6.7 is the factory standard for many of the world's most popular pleasure crafts produced from 2012 to today.

Express & Motor Yachts

  • Sea Ray 400 & 440 Sundancer 480HP
  • Tiara 39 & 43 Open 480HP
  • Sabre 42 Salon Express 425HP
  • Meridian 341 & 391 Sedan 380HP

Trawlers & Down East

  • Grand Banks 41 Heritage 425HP
  • Back Cove 34 & 37 480HP
  • Mainship 400 Trawler 380HP
  • Nordic Tug 37 & 42 380HP

Sportfish & Specialized

  • Cabo 40 Express 550HP
  • Ocean Yachts 37 Billfish 480HP
  • Metal Shark Patrol Craft 480HP
  • Brunswick Government RIBs 425HP
💻

The Common Rail Core

The QSB 6.7 is a precision-engineered machine. Because it relies on High-Pressure Common Rail (HPCR) technology and advanced ECM tuning, the health of your engine core is vital. The 8-digit Engine Serial Number (ESN), found on the rocker cover, is the key to ensuring your replacement long block is configured exactly to your vessel's original specifications.

Is your engine showing signs of high-hour wear or fuel system failure? Don't just patch a symptom. A Choate-remanufactured QSB 6.7 provides a CNC-blueprinted, balanced foundation that restores the factory-quiet performance and smoke-free operation your boat was built for.

Why the 6.7L Fails

From dropped valves to common rail contamination, we’ve analyzed the most frequent causes of QSB 6.7 failures. Learn how our build process corrects these factory flaws to provide a more durable engine than the original.

THE CHOATE ADVANTAGE

Modern Power, Built to Last

Our remanufactured QSB 6.7 long blocks are CNC machined to resolve factory oiling constraints, ensuring your common rail diesel runs cooler and longer.


View QSB 6.7 Options

Talk to a QSB Expert: 901-553-9847