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Mitsubishi 4G61 specs: 1.6L (98 ci) 4-cylinder, 82.3 x 75 mm (3.2402 x 2.9528 in) bore and stroke. Built 1991–1992. Used in the Mitsubishi Mirage.
The Mitsubishi 4G61 is oversquare — the 3.2402" bore exceeds the 2.9528" stroke by 9.7% — a layout that favors airflow and RPM over leverage at the crank. The 2.9528" stroke does not reach 4,000 ft/min of mean piston speed until about 8,150 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 24.5 ci (401 cc).
It is one of 3 engines in the Mitsubishi 98ci family, all of them 98 ci — the differences between them are in compression, heads and rating, not displacement. 2 factory variants share these dimensions across 1991–1992.
| Displacement | 98 ci / 1.6 L |
|---|---|
| Bore | 3.2402" |
| Stroke | 2.9528" |
| Cylinders | 4 |
| Configuration | I4 |
| Bore/stroke ratio | 1.097 |
| Fuel type | gas |
|---|---|
| Years | 1991–1992 |
| Bore/stroke character | 1.097 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,953 ft/min — conservative for a street engine |
| Displacement per cylinder | 24.5 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 |
|---|---|---|
| 1991 | — | 4G61 |
| 1992 | — | 4G61 |
1 factory vehicle, 1991–1992. Each year opens that model's engine table.