Cummins QSB3.9-G31 vs Isuzu 4LE2T
The Cummins QSB3.9-G31 and Isuzu 4LE2T are both diesel generator engines in a similar power class. Both are rated at roughly 31 kVA. Displacement is 3.9 L versus 2.179 L. The table below compares their full specifications side by side.
| Specification | Cummins QSB3.9-G31 | Isuzu 4LE2T |
|---|---|---|
| Headline rating | 31 kVA | 31 kVA |
| Standby (50 Hz) | 25 kWe | 24.8 kWe |
| Prime (50 Hz) | 20 kWe | 22.5 kWe |
| Standby (60 Hz) | — | 29.7 kWe |
| Prime (60 Hz) | — | 27 kWe |
| Displacement | 3.9 L | 2.179 L |
| Configuration | L4 | L4 |
| Cylinders | 4 | 4 |
| Rated speed | 1,500 RPM | 1,500 / 1,800 RPM |
| Fuel | Diesel | Diesel |
| Cooling | Liquid-Cooled | Liquid-Cooled |
| Emissions | Unregulated | U.S. EPA Final Tier 4 |
| Dry weight | — | — |
| Origin | China | Japan |
Choosing between Cummins QSB3.9-G31 and Isuzu 4LE2T
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.