See other engines in this family
Toyota 3K-C specs: 1.2L (71 ci) 4-cylinder, 75 x 66 mm (2.9528 x 2.5984 in) bore and stroke, 9:1 compression. Rated 55-73 hp, 1971–1979.
The Toyota 3K-C is oversquare — the 2.9528" bore exceeds the 2.5984" stroke by 13.6% — a layout that favors airflow and RPM over leverage at the crank. The 2.5984" stroke does not reach 4,000 ft/min of mean piston speed until about 9,250 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 17.8 ci (291 cc).
9:1 is low by modern standards and generally happy on regular pump fuel.
9 factory variants share these dimensions, rated from 55 to 73 hp across 1971–1979.
| Displacement | 71 ci / 1.2 L |
|---|---|
| Bore | 2.9528" |
| Stroke | 2.5984" |
| Cylinders | 4 |
| Configuration | I4 |
| Compression ratio | 9:1 |
| Bore/stroke ratio | 1.136 |
| Fuel type | gas |
|---|---|
| Advertised HP | 55–73 hp |
| Years | 1971–1979 |
| Bore/stroke character | 1.136 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,598 ft/min — conservative for a street engine |
| Displacement per cylinder | 17.8 ci |
| Static compression | 9:1 — low by modern standards, generally happy on regular pump fuel |
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 | 73 hp | 3K-C |
| 1972 | — | 3K-C |
| 1973 | — | 3K-C |
| 1974 | — | 3K-C |
| 1975 | 55 hp | 3K-C |
| 1976 | 55 hp | 3K-C |
| 1977 | 55 hp | 3K-C |
| 1978 | — | 3K-C |
| 1979 | — | 3K-C |
1 factory vehicle, 1971–1979. Each year opens that model's engine table.