Cummins Marine Diesel Engines

The QSB (based on the 5.9/6.7L B-series), QSC (8.3L C-series) and QSL (9.0L) are Cummins' modern electronically controlled marine diesels with common-rail injection, turbocharging and aftercooling. They cover roughly 250 to 700+ HP and are the standard power for express sport-fishers, downeast boats and mid-size cruisers, often in twin-engine installations.

Because these engines are electronic, the rating, software calibration and gear must match your application. We confirm the exact QSB/QSC/QSL variant, rating and drive so your replacement integrates correctly.

Before the QS series, Cummins marine power was dominated by the mechanical 6BT (5.9L inline-6) and 6CT/6CTA (8.3L inline-6) engines. These are bulletproof, simple to service and found in countless trawlers, sport-fishers and commercial boats. Their mechanical injection means no electronics to troubleshoot, which many owners prefer.

Parts and rebuild support for these legacy engines remain excellent. We can supply used running take-outs, rebuilt engines or remanufactured long blocks, and confirm the rating, marine gear and cooling for your installation.

A used running Cummins is the most economical option when your gear and accessories are healthy. Rebuilt engines renew worn parts; remanufactured engines are machined to factory spec with new internals for near-new reliability and many thousands of hours of service. Long block or complete builds are both available.

Every Cummins marine engine carries a 6-month warranty with extended coverage available, ships nationwide by freight, and is typically sold on core exchange. Send us your model (QSB/QSC/QSL or 6BT/6CT), rating, hours, gear and cooling type for a free quote.