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Mazda Skyactiv-G specs: 2.488L (151.8 ci) 4-cylinder, 89 x 100 mm (3.5039 x 3.9370 in) bore and stroke, 13:1 compression. Rated 181-187 hp. DOHC.
The Mazda Skyactiv-G is undersquare — the 3.937" stroke exceeds the 3.5039" bore by 11.0% — 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 38.0 ci (622 cc).
13:1 on aluminum heads is high for a production gasoline engine; running a ratio like that on pump fuel depends on chamber design and fuel delivery rather than the number alone.
It is one of 13 engines in the Skyactiv-G family, sitting between the 91.3 ci and 201.4 ci members. 3 factory variants share these dimensions, rated from 181 to 187 hp. Factory fitments include the Mazda 6, Mazda CX-5, Mazda CX-50 and 5 others.
| Displacement | 151.8 ci / 2.488 L |
|---|---|
| Bore | 3.5039" |
| Stroke | 3.937" |
| Cylinders | 4 |
| Compression ratio | 13:1 |
| Bore/stroke ratio | 0.89 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 181–187 hp |
| Bore/stroke character | 0.890 — 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 | 38.0 ci |
| Static compression | 13:1 — high enough that pump premium or better is normally required |
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 |
|---|---|---|
| — | 181 hp | PY-VP |
| — | 187 hp | PY-VPS |
| — | 187 hp | PY-VPS |