Caterpillar · Cat D-Series GC (Diesel)

Cat D800 GC

800 kW standby / 725 kW prime · Diesel · Liquid-cooled

800 kW diesel standby generator from Cat's GC value-engineered line. C27 V-12 engine with simplified controls for mission-critical standby.

Standby power
800 kW / 725 kW prime
Voltage options
277/480V, 346/600V
Frequency / Phase
60 Hz · 3-phase
Engine
Caterpillar C27 · 27L
EPA / Emissions
Tier 2

Overview#

The Cat D800 GC is an 800-kilowatt diesel standby generator marking the transition to V-12 engines in Cat's GC value-engineered line. The C27 engine (27.0L) delivers mission-critical power for data centers, hospitals, and large campus facilities at the GC line's optimized price point.

V-12 territory#

The step from 700 kW (C18 inline-6) to 800 kW (C27 V-12) is a platform change. The C27's 27 liters across 12 cylinders provide excellent reserve capacity, smooth power delivery, and the robustness expected in mission-critical applications. The GC package makes this capability accessible at a lower price than the standard C27 genset.

Our service perspective#

The C27 V-12 is a different maintenance proposition than the inline-6 models below it — dual turbochargers, more cylinders, and larger fluid volumes. We service these alongside our standard C27 fleet using identical procedures. The added complexity is justified at this power level by the C27's proven reliability in critical applications.

Engineering specifications

Physical

Length
172 in
Width
68 in
Height
88 in
Wet weight
14,200 lb

Fuel system & runtime

Fuel use @ full load
54 GPH
Fuel use @ 75% load
41 GPH

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Adjust load percent and tank size to estimate runtime. Pre-filled with this model's spec where available.

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Estimated runtime

4.8 hours(0.2 days)

Fuel consumption ≈ 41.66 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 Cat D800 GC under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.

Oil & filter
Every 500 hours or 12 months
Coolant change
Every 6000 hours
Air filter
Every 1000 hours
Fuel filter
Every 500 hours
Major overhaul
20,000 hours
Load bank test
Every 12 months

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.

ComponentSymptomTypical hoursSeverity
Fuel qualityInjector fouling, filter clogging4,380+moderate
Turbocharger(s)Reduced power, oil in intake, turbo noise18,000+moderate
Battery banksSlow crank, failed 10-second start8,760+minor
Coolant heaterCold start issues, block heater element failure10,000+minor

Frequently Asked Questions

What is the Cat D800 GC?
The D800 GC is Cat's 800 kW value-engineered diesel generator — the first V-12 model in the GC line, using the C27 engine (27.0L). It enters the mission-critical segment for data centers, hospitals, and large campuses.
Why does the D800 GC use a Tier 2 engine?
Large-displacement engines like the C27 V-12 are regulated under different EPA categories than smaller engines. The C27 at this displacement class meets Tier 2 standards, which is standard for emergency standby generators in this power range.

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