Overview#
The Cat C3.3 is a 45-kilowatt diesel generator set — a compact, versatile platform that bridges the gap between Cat's smallest gensets and the mid-range C4.4/C7 lineup. Powered by the Cat C3.3 turbocharged inline-4 engine with 3.3 liters of displacement, it serves both standby and prime power applications for small commercial facilities, telecom sites, and remote installations.
The C3.3 package includes an integrated 57.9-gallon fuel tank, providing roughly 21 hours of runtime at 75% load without external fuel supply. At 75.8 inches long and under 2,000 pounds dry weight, it fits standard equipment pads and can be transported on a standard utility trailer.
Standby and prime flexibility#
The C3.3 offers both standby (45 kW) and prime (40 kW) ratings at 60 Hz, making it suitable for applications beyond emergency backup. Prime-rated installations can run unlimited hours at variable load, which opens up construction sites, temporary facilities, and locations without reliable utility service. The mechanical governor and inline fuel injection keep the power train simple and field-serviceable, while the turbocharged aspiration provides the power density needed to keep the package compact.
Our service experience#
The C3.3 is common at small retail and telecom sites in our Northern California territory. The integral fuel tank simplifies installation — no separate day tank or fuel piping required — and the compact footprint fits tight equipment yards. The turbocharger is the component we monitor most closely on these units; regular oil sampling through Cat's S.O.S program catches bearing wear before it becomes a field failure. For standby installations, we recommend monthly exercise under load and annual fuel polishing to prevent the injector fouling that comes from diesel sitting idle for months at a time.
