Caterpillar CG18 vs Generac SG500
The Caterpillar CG18 and Generac SG500 are both natural gas generator engines in a similar power class. Both are rated at roughly 625 kVA. Displacement is 18.1 L versus 25.8 L. The table below compares their full specifications side by side.
| Specification | Caterpillar CG18 | Generac SG500 |
|---|---|---|
| Headline rating | 625 kVA | 625 kVA |
| Standby (50 Hz) | — | — |
| Prime (50 Hz) | — | — |
| Standby (60 Hz) | 500 kWe | 500 kWe |
| Prime (60 Hz) | — | 455 kWe |
| Displacement | 18.1 L | 25.8 L |
| Configuration | L6 | V12 |
| Cylinders | 6 | 12 |
| Rated speed | 1,800 RPM | 1,800 RPM |
| Fuel | Natural Gas | Natural Gas |
| Cooling | Liquid-Cooled | Liquid-Cooled |
| Emissions | U.S. EPA Stationary | Unregulated |
| Dry weight | — | — |
| Origin | United States | United States |
Choosing between Caterpillar CG18 and Generac SG500
Use this comparison as an engineering shortlist, then confirm the complete generator package against load profile, voltage, 50/60 Hz frequency, duty class, emissions rules, cooling margin, altitude, ambient temperature, enclosure design, controller features, and alternator sizing.