Overview#
The Cat C27 is a 680-800 kW diesel standby generator powered by the C27 ACERT engine -- a 27.03-liter, V-12 turbocharged-aftercooled diesel. It fills the power segment between Cat's mid-range C18 and the megawatt-class C32, making it a workhorse for commercial and industrial standby installations that need sub-megawatt power from a single unit.
The C27 is EPA certified for stationary emergency use only, meeting Tier 2 nonroad equivalent emission standards. Standard equipment includes the EMCP 4 controller platform, package-mounted radiator, and 24V electric starting system. The generator set accepts 100% rated load in one step per NFPA 110 and meets ISO 8528-5 transient response requirements.
The C27 ACERT platform#
The C27 uses Cat's MEUI (Mechanically-actuated Electronically-controlled Unit Injection) fuel system with the ADEM A4 electronic governor. This combination provides precise fuel delivery and transient response without the complexity of common-rail injection. The 16.5:1 compression ratio and ATAAC (Air-to-Air Aftercooled) intake system deliver consistent performance across the full load range.
Key specifications from the OEM spec sheet:
- Bore x stroke: 137.2 mm x 152.4 mm (5.4 in x 6 in)
- Displacement: 27.03 L (1,649.47 in3)
- Compression ratio: 16.5:1
- Combustion air flow: 1,984 cfm at full load
- Exhaust gas flow: 5,351 cfm at 943.6 degrees F
Our service experience#
The C27 is commonly found in mid-size commercial buildings, municipal facilities, and healthcare settings across Northern California. The V-12 configuration requires balanced attention to both turbocharger banks during routine inspections. The MEUI fuel system is reliable but demands clean fuel -- in standby installations where the unit runs infrequently, fuel quality management (polishing and biocide treatment) is the single most important maintenance task. Cat's S-O-S fluid analysis program is strongly recommended for trending engine wear metals across the low-run-hour intervals typical of standby duty.
