Caterpillar C18 vs Cummins QST30G1
The Caterpillar C18 and Cummins QST30G1 are both diesel generator engines in a similar power class. Both are rated at roughly 782 kVA. Displacement is 18.13 L versus 30 L. The table below compares their full specifications side by side.
| Specification | Caterpillar C18 | Cummins QST30G1 |
|---|---|---|
| Headline rating | 780 kVA | 783 kVA |
| Standby (50 Hz) | 624 kWe | 626 kWe |
| Prime (50 Hz) | 564 kWe | 582 kWe |
| Standby (60 Hz) | 750 kWe | 751 kWe |
| Prime (60 Hz) | 680 kWe | 700 kWe |
| Displacement | 18.13 L | 30 L |
| Configuration | L6 | V12 |
| Cylinders | 6 | 12 |
| Rated speed | 1,500 / 1,800 RPM | 1,500 / 1,800 RPM |
| Fuel | Diesel | Diesel |
| Cooling | Liquid-Cooled | Liquid-Cooled |
| Emissions | U.S. EPA Tier 2 | Unregulated |
| Dry weight | — | — |
| Origin | United States | United States |
Choosing between Caterpillar C18 and Cummins QST30G1
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. The Cummins QST30G1 has the higher headline kVA rating in this pair, but site conditions and duty cycle can still change the final recommendation.