What engine does the Cummins C900 D6 use?

The C900 D6 uses the Cummins QST30-G3 -- a 30-liter, V-12 diesel engine. The V-12 configuration provides smooth power delivery and high power density for the 900 kW class. This is the entry point for V-configuration engines in Cummins' D6 diesel lineup.

What are the standby and prime ratings of the C900 D6?

Standby rating is 900 kW (1125 kVA) at 60 Hz, 0.8 power factor. Prime rating is 820 kW (1025 kVA). Both at 1800 rpm, 60 Hz, three-phase.

What are the service intervals for the C900 D6?

Oil and filter changes are due at 500 hours or 12 months. Air filter replacement at 1,000-hour intervals. Fuel filter at 500 hours. Coolant flush at 6,000 hours. Major overhaul interval is 40,000 hours under standard standby duty conditions.

How does the C900 D6 compare to the C800 D6?

The C900 D6 steps up to the QST30-G3 (30L, V-12) from the QSK23-G3 (23.1L, inline-6) in the C800 D6. The V-12 configuration is larger and heavier but provides smoother power delivery and more headroom at 900 kW. Both share 40,000-hour major overhaul intervals.

Can {company} service the C900 D6 in Northern California?

Yes. OnPoint Generators provides authorized Cummins service for large commercial diesel generators across the San Francisco Bay Area and Northern California. V-12 engines require attention to bank-to-bank balance during service -- our technicians use Cummins INSITE diagnostics for injector calibration and cylinder contribution analysis.

Cummins · Cummins D6 Commercial Diesel

Cummins C900 D6

Name: Cummins C900 D6
Brand: Cummins
SKU: c900-d6

900 kW standby / 820 kW prime · Diesel · Liquid-cooled

900 kW diesel standby generator with QST30-G3 30L V-12 engine. PowerCommand control, liquid-cooled, for data center, hospital, and mission-critical standby applications.

Standby power: 900 kW / 820 kW prime
Voltage options: 277/480V, 346/600V, 4160V
Frequency / Phase: 60 Hz · 3-phase
Engine: Cummins QST30-G3 · 30L
EPA / Emissions: Tier 2

Commercial Manufacturing Data Centers Healthcareparalleling-array

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Overview#

The Cummins C900 D6 is a 900 kW standby diesel generator set powered by the QST30-G3 -- a 30-liter, V-12 diesel engine. Rated at 1125 kVA standby and 1025 kVA prime at 60 Hz, the C900 D6 is the entry point for V-configuration engines in Cummins' D6 commercial diesel lineup, bridging the gap between the inline-6 QSK23 platform (up to 800 kW) and the larger QSK38 V-12 (1100+ kW).

The QST30-G3 V-12 configuration provides inherently smooth power delivery with balanced firing order across both banks. The 30-liter displacement delivers 900 kW at a conservative power-to-displacement ratio, contributing to the 40,000-hour major overhaul interval. Turbocharged and aftercooled with electronic fuel injection control, the QST30-G3 offers modern emissions performance and fuel efficiency.

The C900 D6 is commonly deployed in Tier III+ data centers, large hospital campuses, and industrial plants where near-megawatt standby is required. PowerCommand 2.3 and 3.3 controllers support paralleling for multi-genset configurations, and medium-voltage options (4160V) are available for campus distribution switchgear.

Engineering specifications

Physical

Length: 130 in
Width: 72 in
Height: 82 in
Dry weight: 9,500 lb

Fuel system & runtime

Fuel use @ full load: 63 GPH
Fuel use @ 75% load: 47 GPH
Fuel use @ 50% load: 33 GPH

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Estimated runtime

4.1 hours(0.2 days)

Fuel consumption ≈ 48.60 GPH at 75% load. Estimate based on industry-typical 1800 RPM standby curves (≈0.07 GPH/kW at full load). Actual consumption varies by engine, ambient temperature, fuel quality, and tuning.

Service intervals

Manufacturer-recommended intervals for the Cummins C900 D6 under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.

Oil & filter: Every 500 hours or 12 months
Air filter: Every 1000 hours
Fuel filter: Every 500 hours
Major overhaul: ≈ 40,000 hours

Common failure modes

What we've seen fail on this platform. Use as a service-planning reference, not a diagnostic — actual failure modes depend heavily on duty cycle and maintenance history.

Component	Symptom	Typical hours	Severity
Fuel injection system	Injector fault codes, rough running, power imbalance between banks	—	moderate
Turbocharger(s)	Reduced boost, excessive smoke, turbo bearing noise	—	moderate
Cooling system (V-12 dual-bank)	Coolant temperature exceedances, uneven bank cooling	—	severe
Fuel quality / tank degradation	Filter clogging, hard starting, injector fouling from stagnant fuel	—	moderate
Starting system (24V battery bank)	Slow crank, failed start requirement on infrequently exercised units	—	minor

Frequently Asked Questions

What engine does the Cummins C900 D6 use?: The C900 D6 uses the Cummins QST30-G3 -- a 30-liter, V-12 diesel engine. The V-12 configuration provides smooth power delivery and high power density for the 900 kW class. This is the entry point for V-configuration engines in Cummins' D6 diesel lineup.
What are the standby and prime ratings of the C900 D6?: Standby rating is 900 kW (1125 kVA) at 60 Hz, 0.8 power factor. Prime rating is 820 kW (1025 kVA). Both at 1800 rpm, 60 Hz, three-phase.
What are the service intervals for the C900 D6?: Oil and filter changes are due at 500 hours or 12 months. Air filter replacement at 1,000-hour intervals. Fuel filter at 500 hours. Coolant flush at 6,000 hours. Major overhaul interval is 40,000 hours under standard standby duty conditions.
How does the C900 D6 compare to the C800 D6?: The C900 D6 steps up to the QST30-G3 (30L, V-12) from the QSK23-G3 (23.1L, inline-6) in the C800 D6. The V-12 configuration is larger and heavier but provides smoother power delivery and more headroom at 900 kW. Both share 40,000-hour major overhaul intervals.
Can OnPoint Generators service the C900 D6 in Northern California?: Yes. OnPoint Generators provides authorized Cummins service for large commercial diesel generators across the San Francisco Bay Area and Northern California. V-12 engines require attention to bank-to-bank balance during service -- our technicians use Cummins INSITE diagnostics for injector calibration and cylinder contribution analysis.

Compatible equipment

Transfer switches

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