Description
Cummins QSB6.7 355HP Marine Diesel Engine – Product Overview
The Cummins QSB6.7 355HP Marine Diesel Engine is a professional-grade marine propulsion engine designed for buyers who need dependable diesel power in a compact and proven platform. With 355 horsepower, this engine sits in a practical power range for commercial vessels, cruisers, offshore fishing boats, workboats, and repower applications.
This engine belongs to Cummins’ respected QSB marine diesel family, known for combining compact displacement, electronic fuel control, and strong marine performance. It is built around a 6.7-litre inline 6-cylinder, 4-stroke diesel configuration, giving buyers smooth power delivery and dependable torque.
The engine uses Bosch High-Pressure Common Rail fuel delivery, helping support efficient combustion, cleaner operation, and responsive performance. It is also turbocharged and seawater aftercooled, improving power output and air management under marine load.
For buyers comparing Cummins marine engines, 355HP diesel engines, QSB6.7 repower engines, commercial boat engines, and inboard diesel propulsion systems, the Cummins QSB6.7 355HP Marine Diesel Engine offers a strong balance of power, compliance, and long-term reliability.
Built for Repower Projects and Demanding Marine Use
The Cummins QSB6.7 355HP Marine Diesel Engine is designed for boats that need dependable inboard diesel propulsion without moving into a larger engine class. Its 355HP output makes it suitable for commercial boats, offshore fishing vessels, cruisers, workboats, utility craft, and performance-focused marine applications.
This engine is especially relevant for marine repower projects. Boat owners replacing older diesel engines often need a modern engine with better fuel control, emissions compliance, dependable parts support, and a compact installation profile.
The 6.7-litre displacement gives the engine enough capacity for strong marine torque while remaining practical for many mid-range vessel installations. This makes it a strong option for buyers who need dependable power but still care about engine room space and weight planning.
Its EPA Tier 3 marine certification also makes it useful for buyers who need a compliant diesel engine for regulated applications. Emissions compliance can be especially important for commercial users, charter vessels, and repower projects.
Customers can compare this product with other Cummins marine engines, QSB models, inboard diesel engines, commercial propulsion systems, heat exchanger cooled engines, and marine repower packages.
Inline 6-Cylinder Diesel Power
The Cummins QSB6.7 355HP Marine Diesel Engine uses an inline 6-cylinder, 4-stroke diesel configuration. This layout is widely valued in marine applications because it supports smooth operation, steady torque, and dependable power delivery.
The 355HP power output gives the engine enough strength for vessels that need serious propulsion without requiring an oversized engine package. This makes it useful for fishing boats, cruisers, workboats, and commercial marine operations.
Its turbocharged design helps improve airflow into the engine, supporting stronger output from the 6.7-litre platform. Turbocharging is important in marine diesel engines because vessels often operate under heavy and continuous load.
The seawater aftercooled setup helps manage charge-air temperature, supporting more efficient combustion and stronger performance. Aftercooling is a valuable feature for engines operating in demanding marine environments.
For buyers who need a compact but capable diesel engine, the Cummins QSB6.7 gives a strong mix of horsepower, torque, and proven inline-six smoothness.
Bosch High-Pressure Common Rail Fuel System
The Cummins QSB6.7 355HP Marine Diesel Engine uses a Bosch High-Pressure Common Rail fuel system, one of the strongest technical features of this engine.
High-Pressure Common Rail technology helps control fuel injection more precisely than older mechanical fuel systems. This can support smoother running, improved throttle response, better fuel efficiency, and cleaner combustion.
For marine use, precise fuel delivery is important because engines operate under changing loads, cruising speeds, docking conditions, and rough-water demands. A well-managed fuel system helps maintain consistent engine behavior across different operating conditions.
This technology also works with the engine’s emissions compliance strategy. Cleaner and more controlled combustion helps support EPA Tier 3 marine certification.
For customers comparing modern marine diesel engines, the Bosch common rail system is a major buyer benefit because it supports performance, efficiency, and refined operation.
Heat Exchanger Cooling With Keel Cooling Option
The Cummins QSB6.7 355HP Marine Diesel Engine is listed with heat exchanger cooling, with keel cooling optional. This gives buyers flexibility depending on vessel type and installation requirements.
Heat exchanger cooling is common in marine diesel engines because it helps manage engine temperature while reducing direct exposure of internal engine coolant passages to raw seawater. This supports better durability and more controlled operating temperatures.
Keel cooling is also available as an option. This can be useful for commercial vessels, workboats, or vessels operating in environments where a keel cooling setup is preferred for durability or application-specific reasons.
Cooling setup should always be confirmed before purchase. The correct cooling system depends on vessel design, operating environment, engine room layout, and marine installation requirements.
For buyers planning a repower, cooling system compatibility is one of the most important details to confirm before installation begins.
EPA Tier 3 Certified Marine Diesel Performance
The Cummins QSB6.7 355HP Marine Diesel Engine is EPA Tier 3 marine certified, making it suitable for buyers who need a compliant marine diesel engine for modern applications.
EPA Tier 3 certification is especially important for commercial users, regulated marine markets, charter operations, and repower projects where emissions requirements may apply.
This certification supports buyer confidence because it shows the engine was designed to meet defined marine emissions standards. Combined with the Bosch common rail fuel system and turbo aftercooled performance, it gives the QSB6.7 a modern technical profile.
For buyers replacing older marine diesel engines, moving to an EPA Tier 3 certified engine can be a major upgrade. It can improve compliance, reduce emissions, and support more efficient engine operation.
This makes the Cummins QSB6.7 a strong choice for customers who need reliable diesel power with cleaner modern performance.
Why the Cummins QSB6.7 355HP Engine Is a Smart Choice
The Cummins QSB6.7 355HP Marine Diesel Engine stands out because it combines 355HP output, 6.7-litre displacement, inline-six diesel smoothness, common rail fuel delivery, turbocharged power, and EPA Tier 3 certification.
Many buyers in this category need more than horsepower alone. They need a marine diesel engine that can deliver strong torque, efficient operation, long-term dependability, and support for demanding vessel use.
The Bosch High-Pressure Common Rail fuel system improves fuel delivery control, while the turbocharged and seawater aftercooled setup supports strong performance under load. The heat exchanger cooling system also adds practical durability for marine use.
The availability of 12V or 24V electrical options improves installation flexibility. This matters for repower projects where the vessel’s existing electrical system must be matched correctly.
For customers looking for a reliable Cummins 355HP marine diesel engine, the QSB6.7 offers a strong mix of power, compliance, and trusted brand support.
Who Should Choose This Marine Diesel Engine
The Cummins QSB6.7 355HP Marine Diesel Engine is best for boat owners, commercial operators, boat builders, marine engineers, and repower specialists who need dependable mid-range diesel propulsion.
It is suitable for fishing vessels, cruisers, workboats, small commercial vessels, utility craft, and inboard marine applications that require 355HP diesel power.
This engine is ideal for buyers who value Cummins reliability, Bosch common rail fuel delivery, EPA Tier 3 certification, turbocharged performance, heat exchanger cooling, and optional keel cooling.
Buyers who need a lower horsepower engine, a higher-output commercial rating, a different cooling configuration, or a complete engine-and-transmission package should compare other Cummins marine engine options before purchase.
Technical Specifications
| Specification | Details |
|---|---|
| Product Name | Cummins QSB6.7 355HP Marine Diesel Engine |
| Brand | Cummins |
| Engine Model | Cummins QSB6.7 |
| Product Type | Marine diesel engine |
| Application | Inboard marine propulsion |
| Power Output | 355 HP |
| Configuration | Inline 6-cylinder, 4-stroke diesel |
| Displacement | 6.7 litres |
| Aspiration | Turbocharged / seawater aftercooled |
| Fuel System | Bosch High-Pressure Common Rail |
| Cooling | Heat exchanger cooled |
| Optional Cooling | Keel cooling optional |
| Emissions Compliance | EPA Tier 3 marine certified |
| Electrical System | 12V or 24V options |
| Rotation | Counterclockwise, facing flywheel |
| Recommended Applications | Repower projects, fishing vessels, cruisers, workboats, commercial boats, utility craft |
| Best Fit | Vessels requiring compact 355HP inboard diesel power |
| Buyer Profile | Boat owners, repower specialists, commercial operators, marine engineers, boat builders |
| Main Benefits | 355HP output, common rail fuel system, turbo aftercooled performance, EPA Tier 3 certification, Cummins reliability |
Key Product Details and Specifications
The Cummins QSB6.7 355HP Marine Diesel Engine delivers 355 HP from a 6.7-litre inline 6-cylinder diesel platform. This makes it suitable for marine applications where strong power, dependable torque, and compact installation planning are important.
The engine uses a 4-stroke diesel configuration, which supports efficient and reliable operation for inboard propulsion. Its inline-six design gives buyers smooth power delivery and strong diesel performance.
The turbocharged and seawater aftercooled setup supports higher output and better air management under load. This is valuable for vessels that need dependable acceleration, cruising power, and load-carrying capability.
The Bosch High-Pressure Common Rail fuel system improves injection control, helping support efficient fuel use, cleaner combustion, smoother running, and responsive performance.
The engine is heat exchanger cooled, with keel cooling optional depending on the vessel’s installation requirements. It is also EPA Tier 3 marine certified, supporting modern emissions compliance.
Electrical system options include 12V or 24V, giving buyers flexibility based on vessel setup. Rotation is listed as counterclockwise when facing the flywheel.
Buy With Confidence
When buying the Cummins QSB6.7 355HP Marine Diesel Engine, customers should confirm vessel size, engine room space, cooling system requirements, electrical system compatibility, drivetrain setup, transmission matching, and rotation requirements.
This engine is a practical choice for buyers who need a Cummins 355HP marine diesel engine with common rail fuel delivery, turbocharged performance, EPA Tier 3 compliance, and cooling flexibility.
Customers can compare this product with related Cummins marine engines, QSB diesel engines, inboard propulsion systems, marine transmissions, repower packages, heat exchanger cooled engines, and keel cooled marine engines.
Professional guidance is recommended for repower and new installation projects. Correct engine sizing, cooling selection, transmission matching, mount alignment, and electrical setup help support safer operation, better efficiency, and stronger long-term reliability.
Frequently Asked Questions
What is the Cummins QSB6.7 355HP Marine Diesel Engine best used for?
The Cummins QSB6.7 355HP Marine Diesel Engine is best used for inboard marine propulsion, repower projects, fishing vessels, cruisers, workboats, commercial boats, and utility craft that need dependable 355HP diesel power.
How much power does the Cummins QSB6.7 produce?
This model produces 355 HP. It is designed for marine applications that require strong mid-range diesel power, dependable torque, and reliable propulsion under load.
What fuel system does the Cummins QSB6.7 use?
The engine uses a Bosch High-Pressure Common Rail fuel system. This supports precise fuel injection, smoother operation, improved fuel efficiency, cleaner combustion, and responsive marine performance.
Is the Cummins QSB6.7 355HP engine turbocharged?
Yes, the Cummins QSB6.7 355HP Marine Diesel Engine is turbocharged and seawater aftercooled. This helps improve power output, air management, and performance under demanding marine operating conditions.
What cooling system does this engine use?
The engine is listed as heat exchanger cooled, with keel cooling optional. Buyers should confirm the correct cooling configuration based on vessel design, engine room layout, and intended use.
Is the Cummins QSB6.7 EPA Tier 3 certified?
Yes, this engine is EPA Tier 3 marine certified. This makes it suitable for buyers who need a modern marine diesel engine that supports current emissions compliance requirements.
What electrical system options are available?
The Cummins QSB6.7 355HP Marine Diesel Engine is available with 12V or 24V electrical system options. Buyers should choose the option that matches their vessel’s existing electrical setup.
