Cummins QST30-G4 Specifications
| Engine Model: Cummins QST30-G4 |
| Engine Type: 4-stroke V-block 12-cylinder turbocharged liquid-cooled diesel |
| Total Displacement: 1860 cu.in (30.5 L) |
| Rated Engine Power: 915-1490 Hp (683-1112 kW) at 1500-1800 rpm |
| Fuel System Type: Quantum electronic fuel injection |
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The Cummins QST30-G4 represents a pinnacle of
heavy-duty industrial engine design, engineered specifically for
demanding generator drive (G-Drive) applications. This V-12
configuration delivers a combination of robust power density and
long-term reliability, optimized for standby, prime, and continuous
power generation roles.
The engine integrates advanced technologies, including a high-pressure
Quantum electronic fuel injection system and a sophisticated two-pump,
two-loop cooling strategy, to achieve exceptional fuel efficiency, lower
emissions, and sustained performance under extreme load conditions. Its
construction emphasizes durability, utilizing a deep-skirt cylinder
block, high-strength cast iron pistons, and Holset turbocharging to
ensure a long service life in critical power environments.
The QST30-G4 is a 4-stroke, V-12 cylinder engine with a total
displacement of 30.5 Liters (1860 cu.in). The bore and stroke measure
140 mm x 165 mm (5.51 in x 6.50 in), a configuration that favors torque
production and mechanical efficiency. The engine employs turbocharging
with a low-temperature aftercooling system, specifically a two-pump,
two-loop design, to maximize air density and combustion quality. The
compression ratio is set at 14.0:1.
The firing order is R1-L1-R5-L5-R3-L3-R6-L6-R2-L2-R4-L4. Dry weight for
the base engine is 3,012 kg (6,640 lbs). When fully configured as a
Coolpac assembly - including the radiator, cooling fan, and charge-air
cooler - the total weight is approximately 3,950 kg. The engine’s
physical dimensions are: Length 3,237 mm, Width 2,000 mm, Height 2,041
mm.
Performance ratings are defined by application duty cycle. At 1500 RPM
(50 Hz), Standby Power (ESP) is rated at 970 kWm (1300 BHP), Prime Power
(PRP) at 880 kWm (1180 BHP), and Continuous Power (COP) at 683 kWm (915
BHP). At 1800 RPM (60 Hz), the Standby Power (ESP) reaches 1112 kWm
(1490 BHP), Prime Power (PRP) is 1007 kWm (1350 BHP), and Continuous
Power (COP) is 832 kWm (1115 BHP).
The cylinder block is constructed from high-strength gray iron,
featuring a deep-skirt design that extends below the crankshaft
centerline. This configuration provides exceptional rigidity, minimizing
vibrational distortion and maintaining precise alignment of the rotating
assembly under high cylinder pressures.
The block incorporates wet-type cylinder liners, which are replaceable
and allow for efficient heat transfer from the combustion chamber to the
coolant. The deep-skirt architecture also contributes to enhanced
sealing of the main bearing caps, ensuring long-term durability in
continuous-duty applications. The structure is ribbed extensively to
dampen mechanical and combustion-induced noise, contributing to a
refined operational profile.
0The engine utilizes individual cylinder heads for each cylinder bank,
constructed from cast iron to ensure thermal stability and resistance to
high combustion loads. Each cylinder head features a cross-flow design
that optimizes volumetric efficiency by separating the intake and
exhaust passages. The valve train consists of four valves per cylinder -
two intake and two exhaust - actuated by a single overhead camshaft per
head.
The valves are made from high-temperature alloys, with the exhaust
valves featuring a stellite-faced tip and a hardened stem for resistance
to wear and corrosion. Valve seat inserts are precision-machined from
wear-resistant materials to maintain sealing integrity over extended
maintenance intervals. The overhead camshaft design reduces
reciprocating mass and allows for precise valve timing control, which is
critical for achieving the engine’s performance and emissions targets.
The QST30-G4 is equipped with a Quantum electronic fuel injection
system. This system utilizes electronic fuel pumps that generate
injection pressures up to 1,100 bar, enabling a high degree of fuel
atomization for complete combustion. The Bosch P8500 LLA direct
injectors are electronically controlled, allowing for precise metering
of fuel per cylinder per cycle.
An integral electronic governor is incorporated into the system,
providing instantaneous response to load changes and maintaining stable
frequency control essential for generator sets. The Electronic Control
Module (ECM) serves as the central processing unit, managing full
authority fuel delivery, engine protection functions such as derate and
shutdown, and communication with external control systems. This system
eliminates mechanical fuel pump linkages, reducing maintenance and
improving reliability.
The lubrication system is a full-pressure, forced-feed design, utilizing
a gear-type positive displacement pump. Total oil system capacity,
including the sump and all filters, is 154 Liters (40.7 U.S. Gal).
Filtration is accomplished through spin-on full-flow and by-pass lube
oil filters. The full-flow filter captures contaminants before they
reach critical bearing surfaces, while the by-pass filter polishes the
oil over time to remove finer particulate matter and extend oil life.
The system includes an integrated oil cooler, which is a plate-and-fin
heat exchanger that maintains optimal oil viscosity under high thermal
loads. A deep-skirt oil pan is standard, designed to maintain oil supply
to the pump during transient movements or in stationary installations.
The cooling system is engineered to manage two distinct thermal loads:
the engine jacket water and the charge air. The engine’s coolant
capacity is 79 Liters for the engine block and heads only, with total
system capacity ranging from 141 to 192 Liters depending on the radiator
and piping configuration. The defining feature is a two-pump, two-loop
independent cooling system. One loop circulates coolant through the
engine block, cylinder heads, and the engine-mounted heat exchanger.
The second, dedicated loop circulates coolant exclusively through the
low-temperature aftercooler. This separation allows the aftercooler to
operate at a significantly lower temperature than the engine jacket
water, densifying the intake air from the turbocharger before it enters
the cylinders. This results in a higher air-to-fuel ratio, improving
combustion efficiency, reducing exhaust gas temperatures, and enhancing
overall engine longevity. The system is designed to integrate with
either a keel-cooling arrangement or a remote radiator.
Air Intake and Turbocharging: The engine is equipped with Holset HX82
turbochargers. This wastegate-equipped turbocharger is selected for its
efficiency in converting exhaust gas energy into boost pressure across a
wide operating range. The intake air is routed through the two-loop
low-temperature aftercooler, which reduces intake manifold temperatures
to near-ambient levels, maximizing air density and power output.
Electrical System: The electrical architecture is a 24-volt starting
system, supported by a 35-amp battery charging alternator. The
alternator is designed to maintain battery state of charge for starting
and ECM power requirements, even under conditions of high parasitic load
from cooling fans and other auxiliaries.
Piston Design: The engine utilizes high-strength cast iron pistons. This
material selection is specific to the G-Drive application, providing
superior thermal stability and resistance to high-temperature creep
compared to aluminum alloys. The iron pistons contribute to consistent
combustion geometry over the life of the engine, ensuring that
performance and emissions characteristics remain stable.
Service intervals are defined by operating duty cycle and fuel quality.
For prime power applications, oil and filter change intervals are
typically scheduled at 500 hours, utilizing high-quality 15W-40
multi-grade oil meeting Cummins CES 20078 or equivalent specifications.
The full-flow and by-pass spin-on oil filters are replaced at each oil
change.
Coolant analysis and supplementation are recommended at 1,000-hour
intervals to maintain proper nitrite and molybdate levels for liner
cavitation protection. Valve lash inspection is scheduled at 1,500
hours, with intake valve clearance set to 0.36 mm (0.014 in) and exhaust
valve clearance to 0.69 mm (0.027 in) on a cold engine.
Fuel system maintenance is limited to filter replacement; the
high-pressure components are non-serviceable and designed for the life
of the engine under proper fuel cleanliness conditions. Fuel filter
change intervals are generally 500 hours, with primary and secondary
filters to be replaced concurrently.
Cylinder head bolts are tightened using a multi-stage process: an
initial torque of 270 Nm (200 lb-ft), followed by a 90-degree rotation,
a 90-degree relaxation, and a final 90-degree rotation. Connecting rod
cap bolts are torqued to 270 Nm (200 lb-ft) plus an additional 90-degree
angle.
Main bearing cap bolts require a torque of 490 Nm (360 lb-ft) plus a
final 120-degree rotation. Flywheel housing bolts are torqued to 180 Nm
(133 lb-ft). Injector clamp hold-down bolts are set to 85 Nm (63 lb-ft).
These values are specific to dry, clean threads lubricated with engine
oil unless otherwise specified in the factory service manual.
The QST30-G4 is specifically engineered for the generator drive market,
with no primary application in on-highway vehicles. Its primary
applications include standby generator sets for critical facilities such
as data centers, hospitals, and telecommunications infrastructure. It is
also extensively used in prime power applications for remote mining
sites, oil and gas field operations, and large-scale construction
projects where grid power is unavailable or unreliable.
The engine’s continuous power rating makes it suitable for cogeneration
(combined heat and power) plants, where waste heat from the cooling and
exhaust systems is recovered for industrial processes or facility
heating. The Coolpac configuration is designed for direct integration
into generator enclosures, simplifying installation and ensuring
optimized airflow for cooling and aftercooling systems in stationary
power generation packages.
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