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Nissan A12A specs: 1.2L (73 ci) 4-cylinder, 75 x 70 mm (2.9528 x 2.7559 in) bore and stroke. Built 1979–1982. Used in the Datsun 210.
The Nissan A12A is oversquare — the 2.9528" bore exceeds the 2.7559" stroke by 7.1% — a layout that favors airflow and RPM over leverage at the crank. The 2.7559" 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 4 cylinders displaces 18.3 ci (299 cc).
It is one of 2 engines in the Nissan 73ci family, all of them 73 ci — the differences between them are in compression, heads and rating, not displacement. 4 factory variants share these dimensions across 1979–1982.
| Displacement | 73 ci / 1.2 L |
|---|---|
| Bore | 2.9528" |
| Stroke | 2.7559" |
| Cylinders | 4 |
| Configuration | I4 |
| Bore/stroke ratio | 1.071 |
| Fuel type | gas |
|---|---|
| Years | 1979–1982 |
| Bore/stroke character | 1.071 — 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 | 18.3 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 |
|---|---|---|
| 1979 | — | A12A |
| 1980 | — | A12A |
| 1981 | — | A12A |
| 1982 | — | A12A |
1 factory vehicle, 1979–1982. Each year opens that model's engine table.