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Mazda Skyactiv-G specs: 1.998L (121.9 ci) 4-cylinder, 83.5 x 91.2 mm (3.2874 x 3.5906 in) bore and stroke, 13:1 compression. Rated 155-181 hp. DOHC.
The Mazda Skyactiv-G is undersquare — the 3.5906" stroke exceeds the 3.2874" bore by 8.4% — a layout that trades peak RPM for leverage and torque low in the range. The 3.5906" stroke puts mean piston speed at 4,000 ft/min around 6,700 RPM, which is where a production bottom end is generally considered at its limit. Each of the 4 cylinders displaces 30.5 ci (499 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 155 to 181 hp. Factory fitments include the Mazda 3, Mazda 6, Mazda CX-3 and 7 others.
| Displacement | 121.9 ci / 1.998 L |
|---|---|
| Bore | 3.2874" |
| Stroke | 3.5906" |
| Cylinders | 4 |
| Compression ratio | 13:1 |
| Bore/stroke ratio | 0.916 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 155–181 hp |
| Bore/stroke character | 0.916 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,591 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 30.5 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 |
|---|---|---|
| — | 155 hp | PE-VPS |
| — | 155 hp | PE-VPS |
| — | 181 hp | PE-VPS (Miata) |