Overview#
The Generac SD175-4 is the EPA Tier 4 Final certified variant of the SD175, a 175-kilowatt industrial diesel standby generator powered by a Generac-branded 6.7-liter turbocharged and aftercooled inline-six engine with electronic fuel injection. Rated at 175 kW standby and 158 kW prime (219/197 kVA), the SD175-4 adds exhaust aftertreatment technology to meet Tier 4 Final emissions standards. This is the highest-output model in the 6.7L T4F platform, sharing the same four power nodes (100, 130, 150, 175 kW) available across the SD Series Tier 4 Final lineup.
The "-4" designation in the model name indicates Tier 4 Final (T4F) compliance. The underlying engine platform -- including the 4-valve cylinder head, electronic injection, and Generac 520 mm alternator that distinguish the SD175 from smaller SD Series models -- carries over to the T4F variant. The SD175-4 adds a diesel particulate filter (DPF) and diesel oxidation catalyst (DOC) in the exhaust system. This makes the SD175-4 suitable for installations in air quality non-attainment zones or projects where local permitting authorities require Tier 4 Final emissions certification.
Generac offers the SD175-4 with enclosure options from open skid through Level 2 sound-attenuated in steel or aluminum with RhinoCoat powder-coated finish. The Digital H control panel provides NFPA 110 Level I and II programmable operation, Modbus communications, and IBP/OSHPD seismic certification availability.
Our Service Experience#
At 175 kW, the SD175-4 operates at the highest output calibration of the 6.7L T4F platform. The aftertreatment system adds maintenance complexity over the standard SD175, and the high exhaust temperatures (approximately 1040 degrees F at full load) mean the DPF and DOC components operate in a demanding thermal environment. Annual aftertreatment inspection and cleaning are essential, and exhaust system components downstream of the aftertreatment must be rated for the elevated temperatures.
The electronic fuel injection system requires clean, dry ULSD fuel. Any fuel contamination or degradation accelerates both injector and aftertreatment component wear. At 13.5 gph full load, fuel turnover is rapid during extended outages, but standby units that run only for weekly exercise need biocide treatment and annual fuel polishing. We recommend loaded exercise cycles of at least 30 minutes at 50% load or higher to support passive DPF regeneration.
