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Infiniti VK56VD specs: 5.6L (341 ci) 8-cylinder, 98 x 92 mm (3.8583 x 3.6220 in) bore and stroke, 10.8:1 compression. Rated 400 hp. DOHC.
The Infiniti VK56VD is oversquare — the 3.8583" bore exceeds the 3.622" stroke by 6.5% — a layout that favors airflow and RPM over leverage at the crank. The 3.622" stroke puts mean piston speed at 4,000 ft/min around 6,650 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 42.6 ci (698 cc).
10.8:1 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 9 engines in the VK family, sitting between the 274 ci and 341.7 ci members. Factory fitments include the Infiniti QX80, Infiniti M56, Infiniti Q70.
| Displacement | 341 ci / 5.6 L |
|---|---|
| Bore | 3.8583" |
| Stroke | 3.622" |
| Cylinders | 8 |
| Compression ratio | 10.8:1 |
| Bore/stroke ratio | 1.065 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 400 hp |
| Bore/stroke character | 1.065 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,622 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 42.6 ci |
| Static compression | 10.8:1 — in the range that usually runs on pump premium |
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