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Saab B201 Turbo specs: 121 ci 4-cylinder, 90 x 78 mm (3.5433 x 3.0709 in) bore and stroke. Rated 135 hp, 1979–1985. Used in the Saab 900.
The Saab B201 Turbo is oversquare — the 3.5433" bore exceeds the 3.0709" stroke by 15.4% — a layout that favors airflow and RPM over leverage at the crank. The 3.0709" stroke does not reach 4,000 ft/min of mean piston speed until about 7,800 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 30.3 ci (496 cc).
It is one of 8 engines in the Saab 121ci family, all of them 121 ci — the differences between them are in compression, heads and rating, not displacement. 3 factory variants share these dimensions, rated at 135 hp across 1979–1985.
| Displacement | 121 ci |
|---|---|
| Bore | 3.5433" |
| Stroke | 3.0709" |
| Cylinders | 4 |
| Configuration | I4 |
| Compression ratio | 7.2–8.5:1 (published figures vary) |
| Bore/stroke ratio | 1.154 |
| Fuel type | gas |
|---|---|
| Advertised HP | 135 hp |
| Years | 1979–1985 |
| Bore/stroke character | 1.154 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,071 ft/min — conservative for a street engine |
| Displacement per cylinder | 30.3 ci |
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 |
|---|---|---|
| 1979 | 135 hp | B201 Turbo |
| 1984 | — | B201 Turbo |
| 1985 | — | B201 Turbo |
1 factory vehicle, 1979–1985. Each year opens that model's engine table.