Bore, stroke, displacement and compression for all 4 Mazda Skyactiv-X engines, compared side by side. Plus rod ratio and head specs where published.
| Displacement | 121.9–152.5 ci |
|---|---|
| Cylinders | 4 |
| Bore | 3.287–3.504" |
| Stroke | 3.591–3.937" |
| Compression | 15.0–16.3:1 |
| Advertised power | 180–200 hp |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| 25 | 152.5 ci | 3.5039" × 3.937" | 15:1 | 200 |
| PY-VPTS (Skyactiv-X) | 152.4 ci | 3.5039" × 3.937" | 16.3:1 | 186 |
| HF-VPS | 122 ci | 3.2874" × 3.5906" | 16.3:1 | 180 |
| HF-VPS | 121.9 ci | 3.2874" × 3.5906" | 16.3:1 | 180–186 |
Both bore and stroke vary across the family, so these are separate castings rather than variations on one block.
All are undersquare — stroke larger than bore, favouring torque low in the range.
Each engine page carries rod ratio, mean piston speed, bore/stroke character and cylinder head specs where published, and links into the calculators with its dimensions already filled in.