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Nissan VQ25HR specs: 2.5L (152.4 ci) 6-cylinder, 85 x 73.3 mm (3.3465 x 2.8858 in) bore and stroke, 10.3:1 compression. Rated 225 hp. DOHC.
The Nissan VQ25HR is oversquare — the 3.3465" bore exceeds the 2.8858" stroke by 16.0% — a layout that favors airflow and RPM over leverage at the crank. The 2.8858" stroke does not reach 4,000 ft/min of mean piston speed until about 8,300 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 25.4 ci (416 cc).
10.3:1 on aluminum heads is in the range that usually runs on pump premium; aluminum sheds heat faster than iron, which makes the same number a little more forgiving.
It is one of 14 engines in the VQ family, sitting between the 121.9 ci and 243.8 ci members. Factory fitments include the Nissan Skyline V36, Nissan Fuga Y50, Infiniti G25.
| Displacement | 152.4 ci / 2.5 L |
|---|---|
| Bore | 3.3465" |
| Stroke | 2.8858" |
| Cylinders | 6 |
| Compression ratio | 10.3:1 |
| Bore/stroke ratio | 1.16 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 225 hp |
| Bore/stroke character | 1.160 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 2,886 ft/min — conservative for a street engine |
| Displacement per cylinder | 25.4 ci |
| Static compression | 10.3:1 — in the range that usually runs on pump premium |
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