Gillette · SP Series (Commercial Gas Standby)

Gillette SP-3500

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

350 kW natural gas / 210 kW LPG stationary standby generator. PSI 14.6L V8 turbocharged engine, Stamford S4L1DF alternator, DSE 7420 MKII. Made in USA.

Gillette Gillette SP-3500 generator — specifications and details
Standby power
350 kW
Voltage options
120/208V, 277/480V, 346/600V
Frequency / Phase
60 Hz · 3-phase
Engine
PSI 14.6L V8 TCAC HO · 14.6L
EPA / Emissions
EPA Stationary Spark Ignition
Alternator
Stamford S4L1DE-311
CommercialHospitalityData CentersHealthcareManufacturingGovernment
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Overview#

The Gillette SP-3500 is a 350-kilowatt natural gas / 210-kilowatt LPG stationary standby generator built on PSI's 14.6L turbocharged V8. It bridges the 13L inline-6 platform (SP-2500P/3000P) and the 21.9L V12 platform (SP-4000/5000), offering a unique 350 kW NG output point with genuine LPG capability (210 kW) that the 13L models cannot achieve.

Stamford S4L1DE alternator (480V three-phase) or S4L1DF (208/240V), DSE 7420 MKII controller, three-phase only.

The PSI 14.6L V8 — a distinct platform#

The 14.6L V8 is not used in any other SP model — it is unique to the SP-3500. Key specifications:

  • 892 cu in / 14.6L V8 — long-stroke configuration (5.04" bore × 5.59" stroke)
  • 10.5:1 compression ratio — consistent with the other large PSI turbocharged blocks
  • 10 main bearings, precision half-shell — high bearing count for the V8 configuration
  • Dual 5" exhaust outlets — two exhaust connections required for installation
  • 52" diameter cooling fan — large radiator required for the 125°F (51.6°C) ambient rating
  • Mechanical output: 536 bhp (NG) / 322 bhp (LPG) at standby

The standby exhaust temperature is 1,382°F (750°C) — among the highest in the SP lineup — requiring careful exhaust system design for confined installations.

350 kW gas standby — commercial context#

At 350 kW, this unit typically backs up entire medium-large commercial buildings or critical circuits in larger campuses. Applications in our service territory:

  • Large hotels (full emergency power for elevators, egress lighting, HVAC, life safety)
  • Hospital-adjacent buildings (imaging, clinical support)
  • Data center pods (2-4 racks of power-dense compute)
  • Industrial facilities with medium-voltage distribution

The SP-3500 is the first SP model requiring dual fuel inlets — confirm gas supply sizing with the utility before design finalization.

Our service experience#

The PSI 14.6L V8 is a well-proven industrial gas engine. V8 architecture means slightly more access complexity than the inline-6 models — rear bank spark plugs require careful scheduling in confined enclosures. At 350 kW, annual load bank testing is critical: a generator this size that has never run at full load will reveal cooling, governor, and fuel system issues that monthly no-load tests miss. We recommend commissioning at 100% rated load for at minimum 2 hours on initial installation.

Engineering specifications

Physical

Length
152 in
Width
72 in
Height
80 in
Wet weight
8,625 lb

Acoustic

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

Fuel system & runtime

BTU/hr @ full load
3,499,000

Documents & downloads

Spec sheets & manuals

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Estimate runtime for the Gillette SP-3500

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

3,675,000 BTU/hr≈ 3675.0 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-3500 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, black smoke under load12,000+moderate
Charge air coolerReduced output, elevated intake temperatures10,000+moderate
Spark plugs / ignition (8 cylinders)Misfire, rough running under load1,500+minor
Exhaust manifoldExhaust leaks, elevated underhood temperatures15,000+minor

Frequently Asked Questions

Why does Gillette use a V8 (14.6L) for the SP-3500 when the SP-3000P uses an inline-6 (13L) for 300 kW?
The SP-3500 steps from the 13L inline-6 platform to a 14.6L V8 to achieve the next power tier (350 kW NG). The V8 architecture delivers higher torque at the same RPM, which PSI uses to add 50 kW NG output (536 bhp at standby) vs. what the 13L inline-6 HO achieves at 469 bhp. The V8 also adds LPG output: 210 kW LPG vs. 165 kW LPG on the 13L models.
What is the LPG standby rating of the SP-3500?
210 kW LPG standby — a meaningful improvement over the 165 kW LPG limit of the 13L inline-6 models. The SP-3500's V8 architecture and LPG fuel system are capable of higher LPG throughput per the larger displacement.
The SP-3500 and SP-3000P have nearly the same dimensions — what is different?
The open footprint is nominally the same (152 x 72 x 80 in) but the Level 2 enclosure for the SP-3500 is slightly shorter (186 x 72 x 94 in vs. 200 x 72 x 94 in for the 3000P). Weight differs: 8,625 lbs vs. 8,175 lbs. The SP-3500 uses dual 2" NPTF fuel inlets vs. one on the 13L models.
What are the dual fuel inlet requirements?
The SP-3500 uses two 2" NPTF fuel inlets at 11-14" water column. Full-load NG consumption: 3,499,000 BTU/hr. Verify gas service capacity and run dual supply lines where the distribution system requires it.
How does the 14.6L V8 differ from the 21.9L V12 used in the SP-4000?
The 14.6L V8 (SP-3500) and 21.9L V12 (SP-4000) are both PSI turbocharged V-configuration engines but different displacement classes. The V12 adds 50% more cylinder count for 400 kW output. The V8 at 14.6L is the more compact option for 350 kW. Oil capacity: 49.7 qt (V8) vs. 49.1 qt (V12) — similar at these output levels.

Compatible equipment

Controllers

Transfer switches

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