See other engines in this family
BMW M30B35 specs: 3.4L (209 ci) 6-cylinder, 92 x 86 mm (3.6220 x 3.3858 in) bore and stroke, 9:1 compression. Rated 208 hp, 1988–1993.
The BMW M30B35 is oversquare — the 3.622" bore exceeds the 3.3858" stroke by 7.0% — a layout that favors airflow and RPM over leverage at the crank. The 3.3858" stroke does not reach 4,000 ft/min of mean piston speed until about 7,100 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 34.8 ci (571 cc).
9:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 2 engines in the BMW 209ci family, all of them 209 ci — the differences between them are in compression, heads and rating, not displacement. 11 factory variants share these dimensions, rated at 208 hp across 1988–1993.
| Displacement | 209 ci / 3.4 L |
|---|---|
| Bore | 3.622" |
| Stroke | 3.3858" |
| Cylinders | 6 |
| Configuration | I6 |
| Compression ratio | 9:1 * |
| Bore/stroke ratio | 1.07 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | gas |
|---|---|
| Advertised HP | 208 hp |
| Years | 1988–1993 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 1988 | M30B35 net | 208 | — | — |
| 1989 | M30B35 net | 208 | — | — |
| 1990 | M30B35 net | 208 | — | — |
| 1991 | M30B35 net | 208 | — | — |
| 1992 | M30B35 net | 208 | — | — |
Factory specification sheet.
| Bore/stroke character | 1.070 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,386 ft/min — conservative for a street engine |
| Displacement per cylinder | 34.8 ci |
| Static compression | 9:1 — low by modern standards, generally happy on regular pump fuel |
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 |
|---|---|---|
| 1988 | — | M30B35 |
| 1988 | 208 hp | M30B35 |
| 1989 | — | M30B35 |
| 1989 | 208 hp | M30B35 |
| 1990 | — | M30B35 |
| 1990 | 208 hp | M30B35 |
| 1991 | — | M30B35 |
| 1991 | 208 hp | M30B35 |
| 1992 | — | M30B35 |
| 1992 | 208 hp | M30B35 |
| 1993 | — | M30B35 |
3 factory vehicles, 1988–1993. Each year opens that model's engine table.