Gillette · SP Series (Commercial Gas Standby)

Gillette SP-4000

400 kW standby · Natural Gas / LPG · Liquid-cooled

400 kW natural gas / 300 kW LPG stationary standby generator. PSI 21.9L V12 turbocharged engine, Stamford S4L1DG alternator, DSE 7420 MKII. Made in USA.

Gillette Gillette SP-4000 generator — specifications and details
Standby power
400 kW
Voltage options
120/208V, 277/480V, 346/600V
Frequency / Phase
60 Hz · 3-phase
Engine
PSI 21.9L V12 TCAC · 21.9L
EPA / Emissions
EPA Stationary Spark Ignition
Alternator
Stamford S4L1DF-311
CommercialHospitalityData CentersHealthcareManufacturingGovernment
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Overview#

The Gillette SP-4000 is a 400-kilowatt natural gas / 300-kilowatt LPG stationary standby generator built on PSI's 21.9L turbocharged V12. It shares the 21.9L block with the SP-5000 (the high-output variant) — the two models together represent the full output range of PSI's largest commercial V12 platform. Three-phase only, Stamford S4L1DF alternator (480V) or S4L1DG (208/240V), DSE 7420 MKII.

At 400 kW, this is a generator for large commercial facilities: full hotel standby power, data centers with significant compute density, hospital non-essential loads, and industrial plants with medium-voltage distribution.

The PSI 21.9L V12 platform#

The V12 configuration at 21.9L is PSI's step up from single-turbo V8 to a larger-displacement multi-cylinder block:

  • 12 cylinders — 14 main bearings for high bearing count stability
  • 1,338 cu in (21.9L) — same bore and stroke as the 14.6L V8 (5.04" × 5.59") but extended to 12 cylinders
  • Dual turbochargers (one per bank, on a V12)
  • 52" pusher fan — large radiator matching the heat rejection at this output
  • Mechanical output: 684 bhp (NG) / 471 bhp (LPG) standby
  • 14 main bearings — full bearing support for the extended crankshaft

The V12 produces 12-cylinder combustion smoothness — minimal torque ripple at 1800 RPM, which is valued in sensitive electrical applications (hospitals, data centers) where generator transients are a concern.

LPG at 400 kW — the PSI V12 advantage#

At 300 kW LPG standby, the SP-4000 is one of the few commercial gas standby generators offering genuine LPG capability above 200 kW. The 21.9L displacement means the engine can flow sufficient LPG vapor to sustain 300 kW without requiring a liquid-withdrawal vaporizer system. For sites with large LPG tanks and no NG service, this is relevant — verify LPG supply design with a licensed LP contractor.

Our service experience#

The PSI V12 at this power level requires careful coordination of ignition maintenance — 12 spark plugs, 12 ignition wires, and dual turbocharger inspections. We structure our SP-4000 service intervals with a dedicated ignition service at 1500 hours separate from the oil change schedule to ensure the full 12-cylinder ignition system is addressed without rushing. At 9,550 lbs open, this unit requires a crane and a planned installation window.

Engineering specifications

Physical

Length
168 in
Width
82 in
Height
92 in
Wet weight
9,550 lb

Acoustic

Sound @ 7m, full load
81 dBA
Enclosure
Sound-attenuated

Fuel system & runtime

BTU/hr @ full load
5,916,000

Documents & downloads

Spec sheets & manuals

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Estimate runtime for the Gillette SP-4000

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

Estimate runtime on this tank

Fuel demand at 75% load

4,200,000 BTU/hr≈ 4200.0 cf/min @ 1,000 BTU/cf

On utility natural gas the runtime is generally unlimited provided the supply line and meter can deliver this BTU/hr at the engine's required inlet pressure (typically 5–14" WC residential, up to 5 psi commercial). Confirm against the OEM's published fuel-pressure spec.

Service intervals

Manufacturer-recommended intervals for the Gillette SP-4000 under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.

Oil & filter
Every 250 hours or 12 months
Coolant change
Every 4000 hours
Air filter
Every 1000 hours
Spark plugs
Every 1500 hours
Major overhaul
≈ 15,000 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
TurbochargerPower loss, excessive smoke under full load12,000+moderate
Ignition system (12 cylinders)Multiple misfires, rough running, reduced output1,500+moderate
Charge air coolerReduced output, elevated intake temperatures10,000+moderate
Battery bank (24V)Slow cranking or failed start8,760+minor

Frequently Asked Questions

What engine does the SP-4000 use?
PSI's 21.9L turbocharged V12 (12-cylinder V-configuration, 1,338 cu in, 10.5:1 compression). At 400 kW NG standby, it produces 684 bhp mechanical — one of PSI's largest commercial spark-ignition engines. The same 21.9L block powers the SP-5000 in a high-output variant.
What is the LPG standby output?
300 kW LPG — a strong LPG rating for this displacement. The V12 at 21.9L has sufficient displacement to deliver meaningful LPG output (vs. the 13L models limited to 165 kW LPG). If dual-fuel flexibility is important, the SP-4000 offers genuine LPG capability for critical applications where NG supply may be interrupted.
What fuel consumption should I plan for?
5,916,000 BTU/hr NG at full load (400 kW). Dual 2" NPTF fuel inlets at 11-14" water column. This is a high-volume gas installation — typically requires a 3" or larger dedicated service main. Verify with utility before design.
What are the cooling system ambient limits?
The SP-4000 radiator is rated to 125°F (51.6°C) ambient for full output. The 52" pusher fan moves 29,000 cfm through the radiator. Heat rejection: 25,760 BTU/min (453 kW) — require adequate airflow clearances around the enclosure.
How does the motor-starting capability compare to smaller models?
Motor starting at 30% voltage dip: 480 kVA (208-240V), 1,100 kVA (480V), 1,280 kVA (600V). At 400 kW rated output, the alternator can handle significant motor starting loads — specify compressor and pump starting requirements for ATS sizing coordination.

Compatible equipment

Controllers

Transfer switches

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