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BMW N73B60 specs: 6.0L (364 ci) 12-cylinder, 89 x 80 mm (3.5039 x 3.1496 in) bore and stroke, 11.3:1 compression. Rated 438 hp, 2003–2008.
The BMW N73B60 is oversquare — the 3.5039" bore exceeds the 3.1496" stroke by 11.2% — a layout that favors airflow and RPM over leverage at the crank. The 3.1496" stroke does not reach 4,000 ft/min of mean piston speed until about 7,600 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 12 cylinders displaces 30.3 ci (497 cc).
11.3:1 is high enough that pump premium or better is normally required.
It is one of 2 engines in the BMW 364ci family, all of them 364 ci — the differences between them are in compression, heads and rating, not displacement. 6 factory variants share these dimensions, rated at 438 hp across 2003–2008.
| Displacement | 364 ci / 6 L |
|---|---|
| Bore | 3.5039" |
| Stroke | 3.1496" |
| Cylinders | 12 |
| Compression ratio | 11.3:1 * |
| Bore/stroke ratio | 1.112 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | gas |
|---|---|
| Advertised HP | 438 hp |
| Years | 2003–2008 |
| Bore/stroke character | 1.112 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,150 ft/min — conservative for a street engine |
| Displacement per cylinder | 30.3 ci |
| Static compression | 11.3:1 — 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 |
|---|---|---|
| 2003 | 438 hp | N73B60 |
| 2004 | 438 hp | N73B60 |
| 2005 | 438 hp | N73B60 |
| 2006 | 438 hp | N73B60 |
| 2007 | 438 hp | N73B60 |
| 2008 | 438 hp | N73B60 |
1 factory vehicle, 2003–2008. Each year opens that model's engine table.