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Ford Cummins ISB 6.7 specs: 408 ci (6.7L) 6-cylinder, 4.213 x 4.882 in (107 x 124 mm) bore and stroke. Built 2014–2015. Used in the Ford F-650 / F-750.
The Ford Cummins ISB 6.7 is undersquare — the 4.8819" stroke exceeds the 4.2126" bore by 13.7% — a layout that trades peak RPM for leverage and torque low in the range. With a 4.8819" stroke, mean piston speed reaches 4,000 ft/min at only 4,900 RPM — the practical ceiling for a production bottom end — which is why a stroke this long makes its power low and runs out of safe revs early. Each of the 6 cylinders displaces 68.0 ci (1,114 cc).
2 factory variants share these dimensions across 2014–2015.
| Displacement | 408 ci / 6.7 L |
|---|---|
| Bore | 4.2126" |
| Stroke | 4.8819" |
| Cylinders | 6 |
| Configuration | I6 |
| Bore/stroke ratio | 0.863 |
| Fuel type | diesel |
|---|---|
| Years | 2014–2015 |
| Bore/stroke character | 0.863 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 4,882 ft/min — above the 4,500 ft/min mark where most production bottom ends are considered at their limit |
| Displacement per cylinder | 68.0 ci |
Each link opens the calculator with this engine's specs already filled in.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 2014 | — | Cummins ISB 6.7 |
| 2015 | — | Cummins ISB 6.7 |
1 factory vehicle, 2014–2015. Each year opens that model's engine table.