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Mazda P5-VPS specs: 1.5L (91.5 ci) 4-cylinder, 74.5 x 85.8 mm (2.9331 x 3.3780 in) bore and stroke, 13:1 compression. Rated 118 hp. DOHC.
The Mazda P5-VPS is undersquare — the 3.378" stroke exceeds the 2.9331" bore by 13.2% — a layout that trades peak RPM for leverage and torque low in the range. The 3.378" stroke does not reach 4,000 ft/min of mean piston speed until about 7,100 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 22.9 ci (375 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. Factory fitments include the Mazda 2, Mazda 3, Mazda MX-5 Miata and 3 others.
| Displacement | 91.5 ci / 1.5 L |
|---|---|
| Bore | 2.9331" |
| Stroke | 3.378" |
| Cylinders | 4 |
| Compression ratio | 13:1 |
| Bore/stroke ratio | 0.868 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 118 hp |
| Bore/stroke character | 0.868 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,378 ft/min — conservative for a street engine |
| Displacement per cylinder | 22.9 ci |
| Static compression | 13:1 — high enough that pump premium or better is normally required |
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