Ram Cummins ISB specs: 4.213 x 4.882 in (107 x 124 mm) bore and stroke, shared by all 5 versions. Displacement, compression and factory ratings.
| Displacement | 408 ci |
|---|---|
| Cylinders | 6 |
| Bore | 4.213" |
| Stroke | 4.882" |
| Compression | 16.2–17.3:1 |
| Advertised power | 350–430 hp |
| Years | 2007–2026 |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| Cummins ISB · 4.213" × 4.882" · 17.3:1 | 408 ci | 4.2126" × 4.8819" | 17.3:1 | 350–370 |
| 67 Cummins ISB HO | 408 ci | 4.2126" × 4.8819" | 16.2:1 | 400 |
| Cummins ISB 6.7 | 408 ci | 4.2126" × 4.8819" | — | 350–370 |
| Cummins ISB 6.7 High Output | 408 ci | 4.2126" × 4.8819" | — | 385–420 |
| Cummins 6.7 High Output | 408 ci | 4.2126" × 4.8819" | — | 430 |
All are undersquare — stroke larger than bore, favouring torque low in the range.
Each engine page carries rod ratio, mean piston speed, bore/stroke character and cylinder head specs where published, and links into the calculators with its dimensions already filled in.