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Mazda TC specs: 1.3L (78 ci) 4-cylinder, 73 x 76 mm (2.8740 x 2.9921 in) bore and stroke. Rated 52 hp, 1977. Used in the Mazda GLC / 323.
The Mazda 78ci (TC) is close to square: 2.874" bore against 2.9921" stroke, within 3.9%, which splits the difference between a high-revving layout and a torque layout. The 2.9921" stroke does not reach 4,000 ft/min of mean piston speed until about 8,000 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 19.5 ci (320 cc).
| Displacement | 78 ci / 1.3 L |
|---|---|
| Bore | 2.874" |
| Stroke | 2.9921" |
| Cylinders | 4 |
| Configuration | I4 |
| Bore/stroke ratio | 0.961 |
| Fuel type | gas |
|---|---|
| Advertised HP | 52 hp |
| Years | 1977 |
| Bore/stroke character | 0.961 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 2,992 ft/min — conservative for a street engine |
| Displacement per cylinder | 19.5 ci |
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1 factory vehicle, 1977. Each year opens that model's engine table.