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Nissan G15 specs: 92 ci 4-cylinder, 80 x 74 mm (3.1496 x 2.9134 in) bore and stroke. Rated 85 hp, 1963–1965. Used in the Datsun Roadster.
The Nissan 92ci (G15) is oversquare — the 3.1496" bore exceeds the 2.9134" stroke by 8.1% — a layout that favors airflow and RPM over leverage at the crank. The 2.9134" stroke does not reach 4,000 ft/min of mean piston speed until about 8,250 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 23.0 ci (377 cc).
It is one of 3 engines in the Nissan 92ci family, all of them 92 ci — the differences between them are in compression, heads and rating, not displacement. 3 factory variants share these dimensions, rated at 85 hp across 1963–1965.
| Displacement | 92 ci |
|---|---|
| Bore | 3.1496" |
| Stroke | 2.9134" |
| Cylinders | 4 |
| Configuration | I4 |
| Bore/stroke ratio | 1.081 |
| Fuel type | gas |
|---|---|
| Advertised HP | 85 hp |
| Years | 1963–1965 |
| Bore/stroke character | 1.081 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,913 ft/min — conservative for a street engine |
| Displacement per cylinder | 23.0 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 |
|---|---|---|
| 1963 | — | G15 |
| 1964 | 85 hp | G15 |
| 1965 | 85 hp | G15 |
1 factory vehicle, 1963–1965. Each year opens that model's engine table.