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Mitsubishi 6A12 specs: 2.0L (122 ci) 6-cylinder, 78.4 x 69 mm (3.0866 x 2.7165 in) bore and stroke, 10:1 compression. Rated 197 hp. DOHC.
The Mitsubishi 6A12 is oversquare — the 3.0866" bore exceeds the 2.7165" stroke by 13.6% — a layout that favors airflow and RPM over leverage at the crank. The 2.7165" stroke does not reach 4,000 ft/min of mean piston speed until about 8,850 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 20.3 ci (333 cc).
10:1 on aluminum heads is in the range that usually runs on pump premium; aluminum sheds heat faster than iron, which makes the same number a little more forgiving.
Factory fitments include the FTO, Galant, Diamante.
| Displacement | 122 ci / 2 L |
|---|---|
| Bore | 3.0866" |
| Stroke | 2.7165" |
| Cylinders | 6 |
| Compression ratio | 10:1 |
| Bore/stroke ratio | 1.136 |
| Block material | cast iron |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 197 hp |
| Bore/stroke character | 1.136 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,717 ft/min — conservative for a street engine |
| Displacement per cylinder | 20.3 ci |
| Static compression | 10:1 — in the range that usually runs on pump premium |
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