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Dodge 251ci (1961–1968) specs: 251 ci 6-cylinder, 3.438 x 4.50 in (87.3 x 114.3 mm) bore and stroke. Built 1961–1968. Used in the Dodge Power Wagon.
The Dodge 251ci (1961–1968) is undersquare — the 4.5" stroke exceeds the 3.4375" bore by 23.6% — a layout that trades peak RPM for leverage and torque low in the range. With a 4.5" stroke, mean piston speed reaches 4,000 ft/min at only 5,350 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 41.8 ci (686 cc).
8 factory variants share these dimensions across 1961–1968.
| Displacement | 251 ci |
|---|---|
| Bore | 3.4375" |
| Stroke | 4.5" |
| Cylinders | 6 |
| Configuration | I6 |
| Bore/stroke ratio | 0.764 |
| Fuel type | gas |
|---|---|
| Years | 1961–1968 |
| Bore/stroke character | 0.764 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 4,500 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 41.8 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 |
|---|---|---|
| 1961 | — | — |
| 1962 | — | — |
| 1963 | — | — |
| 1964 | — | — |
| 1965 | — | — |
| 1966 | — | — |
| 1967 | — | — |
| 1968 | — | — |
1 factory vehicle, 1961–1968. Each year opens that model's engine table.