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BMW M60B40 specs: 4.0L (243 ci) 8-cylinder, 89 x 80 mm (3.5039 x 3.1496 in) bore and stroke, 10:1 compression. Rated 282 hp, 1993–1995.
The BMW M60B40 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 8 cylinders displaces 30.4 ci (498 cc).
10:1 is in the range that usually runs on pump premium.
5 factory variants share these dimensions, rated at 282 hp across 1993–1995.
| Displacement | 243 ci / 4 L |
|---|---|
| Bore | 3.5039" |
| Stroke | 3.1496" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 10:1 * |
| Bore/stroke ratio | 1.112 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | gas |
|---|---|
| Advertised HP | 282 hp |
| Years | 1993–1995 |
| 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 | 30.4 ci |
| Static compression | 10:1 — in the range that usually runs on pump premium |
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 |
|---|---|---|
| 1993 | 282 hp | M60B40 |
| 1994 | — | M60B40 |
| 1994 | 282 hp | M60B40 |
| 1995 | — | M60B40 |
| 1995 | 282 hp | M60B40 |
2 factory vehicles, 1993–1995. Each year opens that model's engine table.