Il Cummins QSK78 is a 77.6-liter V18 diesel engine developed for applications that demand very high power over long operating periods. Cummins currently lists the QSK78 for mining and rail applications, with engine ratings from 3,300 to 3,500 HP. The same engine platform also appears in large G-Drive and generator applications.
That range of applications makes the Cummins QSK78 engine more than a single specification. Mining, rail, and power generation use different configurations and ratings. This guide looks at the QSK78 from that perspective, covering its core specifications, power ratings, G-Drive models, major applications, parts, and engine replacement considerations.
What Is the Cummins QSK78?
Il Cummins QSK78 is an 18-cylinder V-engine with a 77.6-liter displacement. Cummins lists a 170 mm bore and 190 mm stroke, giving the engine its large displacement and high power output.
The current Cummins product range includes dedicated QSK78 configurations for mining and rail. The mining version is rated at 3,500 HP, while the rail version is listed at 3,300 HP. The published torque range for the QSK78 family is 10,157 to 14,077 lb-ft.
The QSK78 also has a strong presence in stationary power generation. Cummins offers QSK78 G-Drive engines for 50 Hz and 60 Hz generator applications, including the QSK78-G8, QSK78-G9, and QSK78-G15.
Cummins QSK78 Engine Specs
| Specifiche | Cummins QSK78 |
| Engine family | QSK |
| Configuration | 60° V18 |
| Spostamento | 77.6 L / 4,735 in³ |
| Foro | 170 mm |
| Ictus | 190 mm |
| Power range | 3,300–3,500 HP |
| Power range | 2,461–2,610 kW |
| Torque range | 10,157–14,077 lb-ft |
| Fuel | Diesel |
| Main engine applications | Mining, Rail |
77.6-Liter V18 Configuration
The size of the engine is one of its defining characteristics.
The QSK78 uses 18 cylinders arranged in a 60-degree V configuration. Its 170 mm bore and 190 mm stroke produce a displacement of 77.6 liters, or 4,735 cubic inches.
This large-displacement layout gives the QSK78 engine the capacity to deliver the power required by large mining equipment, rail applications, and high-output generator systems.
Cummins QSK78 Horsepower and Torque
Cummins QSK78 horsepower depends on the application.
The current Cummins product page lists a family range of 3,300 to 3,500 HP. The rail version produces 3,300 HP, while the mining configuration reaches 3,500 HP.
Torque varies in the same way. Cummins lists a family range of 10,157 to 14,077 lb-ft. The rail configuration is listed at 10,157 lb-ft, while the mining configuration reaches up to 14,077 lb-ft.
Cummins QSK78 for Mining
Mining is one of the most important applications for the Cummins QSK78. Cummins currently lists a dedicated QSK78 mining configuration rated at 3,500 HP and 2,610 kW. The current product information also lists non-certified and Tier 4 Final / Stage V configurations.
Cummins describes the QSK78 Tier 4 Final version as a 3,500-horsepower V18 engine for large haul trucks. The company also notes improvements in combustion technology, thermostat and cooling-circuit serviceability, oil filtration, and overhaul-related fuel economy compared with earlier versions.
The mining environment explains why the QSK78 uses such a large displacement. Heavy haul trucks operate under substantial loads, and the engine has to deliver high power while working as part of a much larger drivetrain.
Cummins QSK78 for Rail Applications
Il Cummins QSK78 also has a dedicated rail configuration. Cummins currently lists the QSK78 for rail at 3,300 HP and 2,461 kW, with a Tier 1 certification. Its published torque rating is 10,157 lb-ft.
Rail applications place different demands on the engine from mining equipment. The engine works within a locomotive powertrain, and the final installation includes systems for cooling, controls, exhaust, fuel, and drivetrain integration.
Cummins QSK78 Generator and Genset Applications
The QSK78 is also used as the engine platform for large generator systems.
Cummins currently lists QSK78 G-Drive models for both 50 Hz and 60 Hz applications. The current G-Drive range includes QSK78-G8, QSK78-G9, and QSK78-G15.
| G-Drive Model | Frequency | Prime Power | Potenza in standby | Speed |
| QSK78-G8 | 60 Hz | 2,512 kW | 2,760 kW | 1,800 rpm |
| QSK78-G9 | 50 Hz | 2,200 kW | 2,400 kW | 1,500 rpm |
| QSK78-G15 | 50 Hz | 2,200 kW | 2,400 kW | 1,500 rpm |
Cummins identifies these as diesel G-Drive configurations, with the certification varying by model. The current G-Drive page lists the G8 as non-regulated, the G9 as non-regulated, and the G15 as EPA Tier 2.
This is where QSK78 generator e QSK78 genset searches become particularly relevant. A generator buyer is usually interested in the complete power-generation package, not just the engine.
QSK78 G9
Il QSK78 G9 is a 50 Hz G-Drive configuration.
Cummins lists the QSK78-G9 at 2,200 kW prime power and 2,400 kW standby power, running at 1,500 rpm. The corresponding apparent power ratings are 2,750 kVA prime and 3,000 kVA standby.
That makes the G9 an important configuration for searches such as QSK78 G9 datasheet e QSK78-G9. However, a G9 rating should not be used as a general specification for every QSK78 engine.
QSK78 G8 and G15
The QSK78-G8 serves the 60 Hz market. Cummins lists 2,512 kW prime and 2,760 kW standby power at 1,800 rpm.
The QSK78-G15 is another 50 Hz configuration with 2,200 kW prime and 2,400 kW standby output at 1,500 rpm. Its current G-Drive specification lists EPA Tier 2 certification.
QSK78 Technology and Engine Design
The QSK78 uses several systems designed around high-output diesel operation. Cummins’ generator specification identifies a turbocharged and low-temperature aftercooled design. The engine uses direct fuel injection, while current QSK78 G-Drive documentation specifies Cummins HPI fuel injection.
The G-Drive version also uses a two-pump, two-loop cooling system. Cummins describes the system as a low-temperature aftercooling arrangement designed to separate the cooling circuits. These systems matter because the QSK78 does not produce its power through displacement alone. Air handling, fuel delivery, cooling, lubrication, and electronic controls all work together as part of the engine system.
For technical work, the exact configuration remains important. A specification from a current QSK78 G-Drive engine should not automatically be transferred to an older mining or rail configuration.
Cummins QSK78 Parts
Il Cummins QSK78 parts range covers major engine components as well as fuel, cooling, air, electrical, and overhaul parts.
Typical component groups include:
- Cylinder block and cylinder components
- Crankshaft and connecting-rod components
- Pistons and cylinder liners
- Fuel-system components
- Turbocharger and aftercooling components
- Lubrication-system components
- Cooling-system components
- Gaskets and sealing components
- Starting and electrical components
The QSK78 is a large and highly specialized engine, so component identification needs more information than the family name alone. Mining, rail, and generator installations can use different engine configurations, and older engines may also contain superseded components. For that reason, Cummins QSK78 parts should be matched against the applicable engine model and available identification information before a replacement is quoted.
YIZHI POWER supplies Cummins engines, assemblies, and replacement parts to international B2B customers. As a supplier, YIZHI POWER sources and provides Cummins products rather than manufacturing the Cummins engine itself.
Cummins QSK78 Engine Assembly
A Cummins QSK78 engine assembly is a different requirement from sourcing an individual replacement component.
For a complete engine replacement, the application usually determines which configuration should be considered. A mining haul truck, locomotive, and generator installation can use the same QSK78 family while requiring different engine specifications. Power rating is another important distinction. A 3,500 HP mining engine should not be treated as interchangeable with a 3,300 HP rail configuration simply because both carry the QSK78 name.
YIZHI POWER can supply Cummins engine assemblies for B2B projects, with the required configuration depending on the intended application and available engine information.
Conclusione
Il Cummins QSK78 is a 77.6-liter V18 platform designed for high-output applications. Its current range covers mining and rail engines, while related QSK78 G-Drive configurations support large 50 Hz and 60 Hz generator systems. Power ratings, emissions specifications, and operating details vary between these applications, so the model name alone does not describe every version.
For companies sourcing a Cummins QSK78 engine or related parts, the application should remain central to the selection process. YIZHI POWER supplies Cummins engines, assemblies, and replacement parts for international B2B projects, with product selection based on the required engine configuration and application.
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