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Jaguar V12 5.3 specs: 326 ci 12-cylinder, 90 x 70 mm (3.5430 x 2.7560 in) bore and stroke. Built 1971–1974. Used in the Jaguar E-Type.
The Jaguar V12 5.3 is oversquare — the 3.543" bore exceeds the 2.756" stroke by 28.6% — a layout that favors airflow and RPM over leverage at the crank. The 2.756" stroke does not reach 4,000 ft/min of mean piston speed until about 8,700 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 12 cylinders displaces 27.2 ci (445 cc).
4 factory variants share these dimensions across 1971–1974.
| Displacement | 326 ci |
|---|---|
| Bore | 3.543" |
| Stroke | 2.756" |
| Cylinders | 12 |
| Compression ratio | 7.8–9:1 (published figures vary) |
| Bore/stroke ratio | 1.286 |
| Fuel type | gas |
|---|---|
| Years | 1971–1974 |
| Bore/stroke character | 1.286 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,756 ft/min — conservative for a street engine |
| Displacement per cylinder | 27.2 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 |
|---|---|---|
| 1971 | — | V12 5.3 |
| 1972 | — | V12 5.3 |
| 1973 | — | V12 5.3 |
| 1974 | — | V12 5.3 |
1 factory vehicle, 1971–1974. Each year opens that model's engine table.