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Saab B204R specs: 121 ci 4-cylinder, 90 x 78 mm (3.5433 x 3.0709 in) bore and stroke, 9.2:1 compression. Built 1999. Used in the Saab 9-3.
The Saab B204R 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).
9.2:1 is low by modern standards and generally happy on regular pump fuel.
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.
| Displacement | 121 ci |
|---|---|
| Bore | 3.5433" |
| Stroke | 3.0709" |
| Cylinders | 4 |
| Configuration | I4 |
| Compression ratio | 9.2:1 * |
| Bore/stroke ratio | 1.154 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | gas |
|---|---|
| Years | 1999 |
| 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 |
| Static compression | 9.2:1 — low by modern standards, generally happy on regular pump fuel |
Each link opens the calculator with this engine's specs already filled in.
1 factory vehicle, 1999. Each year opens that model's engine table.