Generac · MD Series (Modular Diesel)

Generac MD500-T4

500 kW standby / 456 kW prime · Diesel · Liquid-cooled

500 kW modular diesel standby generator system, Tier 4 Final emissions. Factory-paralleled configuration with Perkins 18.1L inline-6 engine for N+1 redundancy.

Standby power
500 kW / 456 kW prime
Voltage options
120/208V, 120/240V, 277/480V
Frequency / Phase
60 Hz · 3-phase
Engine
Perkins 2806F-E18TAG1 · 18.1L
EPA / Emissions
Tier 4 Final
Alternator
Generac K0552124N27

Overview#

The Generac MD500-T4 is a 500 kW modular diesel standby generator system meeting EPA Tier 4 Final emissions standards. It uses a Perkins 18.1-liter turbocharged and aftercooled inline-six engine -- larger displacement than the standard MD500's 15.2L Perkins -- paired with diesel exhaust aftertreatment technology including a diesel particulate filter (DPF) and selective catalytic reduction (SCR) system. The DSE G8601 controller manages both generator operation and aftertreatment system functions.

As part of Generac's Modular Power System (MPS) platform, the MD500-T4 is factory-configured with integrated paralleling controls for plug-and-play scalability. The Tier 4 Final compliance makes this model suitable for installations in air quality management districts with strict emissions limits, or for facilities that prioritize environmental responsibility. The modular architecture provides N+1 redundancy with independent serviceability of each module.

Our Service Experience#

The MD500-T4's Tier 4 Final aftertreatment system adds maintenance requirements beyond a standard diesel genset. The DPF requires periodic regeneration, and DEF quality and level must be monitored. Low-runtime standby installations are particularly susceptible to incomplete regeneration cycles, so we recommend exercise runs long enough to complete a full DPF regeneration. The 18.1L Perkins platform is well-proven in this power class, and the paralleling controls follow the same architecture as the rest of the MD Series.

Engineering specifications

Physical

Length
188.5 in
Width
71 in
Height
116.8 in

Fuel system & runtime

Fuel use @ full load
36.5 GPH
Fuel use @ 75% load
27.8 GPH
Fuel use @ 50% load
19.7 GPH

Thermal & ventilation

Heat to coolant
966,495 BTU/hr
Exhaust flow
935 CFM
Exhaust temp
911 °F
Combustion air
1,338 CFM
Ventilation air
25,603 CFM

Documents & downloads

Spec sheets & manuals

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Estimate runtime for the Generac MD500-T4

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

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Estimated runtime

7.1 hours(0.3 days)

Fuel consumption ≈ 28.16 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 Generac MD500-T4 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
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 quality / degradationHard starting, filter clogging, reduced power output4,380+moderate
Paralleling controller synchronizationFailed sync, load sharing imbalance, hunting20,000+moderate
Diesel exhaust aftertreatment systemDPF regeneration faults, DEF quality warnings, increased backpressure4,000+moderate
BatteryFailed to start, slow cranking8,760+minor

Frequently Asked Questions

What is the difference between the MD500-T4 and the MD500?
The MD500-T4 meets EPA Tier 4 Final emissions standards, using a larger Perkins 18.1L engine (versus the 15.2L in the standard MD500) paired with diesel exhaust aftertreatment including a diesel particulate filter (DPF) and selective catalytic reduction (SCR) using diesel exhaust fluid (DEF). The Tier 4 Final variant is required in jurisdictions with strict emissions regulations or for facilities seeking to minimize environmental impact. Both models produce 500 kW standby output with factory-integrated paralleling.
What is the fuel consumption of the MD500-T4?
The MD500-T4 uses the Perkins 2806F-E18TAG1 18.1L engine. At standby rating, fuel consumption is approximately 36.5 gallons per hour at full load, 27.8 gph at 75% load, 19.7 gph at 50% load, and 12.3 gph at 25% load per module. DEF consumption is approximately 1.3 gph at full load.
What voltages are available?
The MD500-T4 is available in three-phase configurations at 120/208V, 120/240V, and 277/480V, all at 60 Hz.

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