See other engines in this family
BMW S38B35 specs: 3.5L (211 ci) 6-cylinder, 93.4 x 84 mm (3.6772 x 3.3071 in) bore and stroke, 9.8:1 compression. Rated 256 hp, 1987–1989.
The BMW S38B35 is oversquare — the 3.6772" bore exceeds the 3.3071" stroke by 11.2% — a layout that favors airflow and RPM over leverage at the crank. The 3.3071" stroke does not reach 4,000 ft/min of mean piston speed until about 7,250 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 35.2 ci (576 cc).
9.8:1 is in the range that usually runs on pump premium.
3 factory variants share these dimensions, rated at 256 hp across 1987–1989.
| Displacement | 211 ci / 3.5 L |
|---|---|
| Bore | 3.6772" |
| Stroke | 3.3071" |
| Cylinders | 6 |
| Configuration | I6 |
| Compression ratio | 9.8:1 * |
| Bore/stroke ratio | 1.112 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | gas |
|---|---|
| Advertised HP | 256 hp |
| Years | 1987–1989 |
| Bore/stroke character | 1.112 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,307 ft/min — conservative for a street engine |
| Displacement per cylinder | 35.2 ci |
| Static compression | 9.8:1 — 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 |
|---|---|---|
| 1987 | 256 hp | S38B35 |
| 1988 | 256 hp | S38B35 |
| 1989 | 256 hp | S38B35 |
2 factory vehicles, 1987–1989. Each year opens that model's engine table.