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Jaguar XK 3.8 specs: 231 ci 6-cylinder, 87 x 106 mm (3.4250 x 4.1730 in) bore and stroke. Rated 265 hp, 1961–1964. Used in the Jaguar E-Type.
The Jaguar XK 3.8 is undersquare — the 4.173" stroke exceeds the 3.425" bore by 17.9% — a layout that trades peak RPM for leverage and torque low in the range. The 4.173" stroke puts mean piston speed at 4,000 ft/min around 5,750 RPM, which is where a production bottom end is generally considered at its limit. Each of the 6 cylinders displaces 38.5 ci (631 cc).
4 factory variants share these dimensions, rated at 265 hp across 1961–1964.
| Displacement | 231 ci |
|---|---|
| Bore | 3.425" |
| Stroke | 4.173" |
| Cylinders | 6 |
| Configuration | I6 |
| Bore/stroke ratio | 0.821 |
| Fuel type | gas |
|---|---|
| Advertised HP | 265 hp |
| Years | 1961–1964 |
| Bore/stroke character | 0.821 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 4,173 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 38.5 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 | 265 hp | XK 3.8 |
| 1962 | 265 hp | XK 3.8 |
| 1963 | 265 hp | XK 3.8 |
| 1964 | 265 hp | XK 3.8 |
1 factory vehicle, 1961–1964. Each year opens that model's engine table.