The Cummins QSK series is a family of high-speed four-stroke V-configuration marine, locomotive, mining, and stationary diesel engines manufactured by Cummins Inc. The marine variants span the QSK19 (in-line six), QSK38 (V12), QSK50 (V16), QSK60 (V16), and QSK95 (V16, the largest), with outputs from approximately 380 kilowatts to 3,000 kilowatts. The QSK is Cummins’ premium high-speed marine product line and one of the principal alternatives to the Caterpillar 3500 series and MTU 4000 series in tugs, supply boats, workboats, and fishing vessels.
Series structure
The current QSK marine portfolio includes the following models:
- QSK19 (in-line six). Bore 159 millimetres, stroke 159 millimetres. Output range approximately 380 to 600 kilowatts.
- QSK38 (V12). Bore 159 millimetres, stroke 159 millimetres. Output range approximately 750 to 1,200 kilowatts.
- QSK50 (V16). Bore 159 millimetres, stroke 159 millimetres. Output range approximately 1,000 to 1,500 kilowatts.
- QSK60 (V16). Bore 159 millimetres, stroke 190 millimetres. Output range approximately 1,500 to 2,200 kilowatts.
- QSK95 (V16). Bore 190 millimetres, stroke 210 millimetres. Output range approximately 2,800 to 3,000 kilowatts.
The QSK19 to QSK50 share a common 159 millimetre bore and stroke architecture and differ only in cylinder count, allowing significant parts commonality and global service support. The QSK60 introduces a longer stroke for greater displacement, and the QSK95 is a clean-sheet larger architecture that extends Cummins into the upper high-speed marine output band.
Fuel system and emissions
The QSK series uses the Cummins Modular Common Rail System (MCRS) on most current variants, providing electronically controlled fuel injection at pressures up to approximately 1,800 bar. EPA Tier 4 Final and IMO Tier III compliance is achieved through selective catalytic reduction with urea aftertreatment on the QSK60 and QSK95; lower-output variants meet Tier III through in-cylinder measures or SCR depending on the specific rating.
The QSK is qualified for marine diesel oil, marine gas oil, ultra-low-sulphur diesel, and biodiesel blends up to B20 on most ratings. Cummins has announced renewable-diesel HVO (hydrotreated vegetable oil) compatibility across the marine product range as biodiesel blend supplies expand.
Applications
The QSK series operates across the same broad commercial high-speed marine niche as the Caterpillar 3500 and MTU 4000 series. Notable application categories include:
- Inland waterway towboats, push-tow units, and ocean-going tugs.
- Offshore supply vessels and anchor handlers.
- Crew boats, fast support vessels, and pilot launches at the upper end of the planing-hull size range.
- Trawlers, longliners, and purse seine fishing vessels.
- Workboats, dredges, and mobile barges.
- Patrol craft and naval auxiliary vessels.
- Onshore standby generation including data centre backup (a major application for the QSK60 and QSK95).
Service network
Cummins supports the QSK marine series through the Cummins distributor and dealer network of approximately 7,500 service locations worldwide, including marine specialist distributors in major ports. The shared parts and service infrastructure with Cummins’ on-highway truck and locomotive engine business is a key selling point in the inland waterway and intermodal markets, where customers operating mixed fleets value common parts logistics.
Comparable engines
The QSK competes principally against:
- Caterpillar 3500 series (closely matched output and rating bands).
- MTU 4000 series (slightly higher power density, premium naval reference).
- MAN D2868 and D2862 (similar output range, German market preference).
- Mitsubishi S16R (Japanese yard preference).
In the upper bracket the QSK95 specifically targets the 2,500 to 3,000 kilowatt high-speed market that historically split between Caterpillar 3500 and MTU 4000 V20.