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Mitsubishi 4G64 specs: 2.4L (143 ci) 4-cylinder, 86.5 x 100 mm (3.4055 x 3.9370 in) bore and stroke, 9:1 compression. Rated 138-145 hp. SOHC.
The Mitsubishi 4G64 is undersquare — the 3.937" stroke exceeds the 3.4055" bore by 13.5% — a layout that trades peak RPM for leverage and torque low in the range. The 3.937" stroke puts mean piston speed at 4,000 ft/min around 6,100 RPM, which is where a production bottom end is generally considered at its limit. Each of the 4 cylinders displaces 35.8 ci (586 cc).
9:1 on aluminum heads is low by modern standards and generally happy on regular pump fuel.
It is one of 9 engines in the Sirius family, sitting between the 122 ci and 145 ci members. 2 factory variants share these dimensions, rated from 138 to 145 hp. Factory fitments include the Eclipse GS, Galant, Outlander and 3 others.
| Displacement | 143 ci / 2.4 L |
|---|---|
| Bore | 3.4055" |
| Stroke | 3.937" |
| Cylinders | 4 |
| Compression ratio | 9:1 |
| Bore/stroke ratio | 0.865 |
| Block material | cast iron |
|---|---|
| Head material | aluminum |
| Valvetrain | SOHC |
| Fuel type | gas |
| Advertised HP | 138–145 hp |
| Bore/stroke character | 0.865 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,937 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 35.8 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 |
|---|---|---|
| — | 138 hp | 4G64 |
| — | 145 hp | 4G64 |