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Nissan A13 specs: 79 ci 4-cylinder, 73 x 77 mm (2.8740 x 3.0315 in) bore and stroke, 8.5:1 compression. Rated 75 hp, 1974. Used in the Datsun B210.
The Nissan 79ci (A13) is undersquare — the 3.0315" stroke exceeds the 2.874" bore by 5.2% — a layout that trades peak RPM for leverage and torque low in the range. The 3.0315" stroke does not reach 4,000 ft/min of mean piston speed until about 7,900 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 19.8 ci (324 cc).
8.5:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 2 engines in the Nissan 79ci family, all of them 79 ci — the differences between them are in compression, heads and rating, not displacement.
| Displacement | 79 ci |
|---|---|
| Bore | 2.874" |
| Stroke | 3.0315" |
| Cylinders | 4 |
| Configuration | I4 |
| Compression ratio | 8.5:1 * |
| Bore/stroke ratio | 0.948 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | gas |
|---|---|
| Advertised HP | 75 hp |
| Years | 1974 |
| Bore/stroke character | 0.948 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,032 ft/min — conservative for a street engine |
| Displacement per cylinder | 19.8 ci |
| Static compression | 8.5:1 — low by modern standards, generally happy on regular pump fuel |
Each link opens the calculator with this engine's specs already filled in.
1 factory vehicle, 1974. Each year opens that model's engine table.