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BMW B48 specs: 2.0L (122 ci) 4-cylinder, 82 x 94.6 mm (3.2283 x 3.7244 in) bore and stroke, 11.1:1 compression. Rated 201 hp, 2025.
The BMW 122ci (B48) is undersquare — the 3.7244" stroke exceeds the 3.2283" bore by 13.3% — a layout that trades peak RPM for leverage and torque low in the range. The 3.7244" stroke puts mean piston speed at 4,000 ft/min around 6,450 RPM, which is where a production bottom end is generally considered at its limit. Each of the 4 cylinders displaces 30.5 ci (500 cc).
11.1:1 is high enough that pump premium or better is normally required.
It is one of 7 engines in the BMW 122ci family, all of them 122 ci — the differences between them are in compression, heads and rating, not displacement.
| Displacement | 122 ci / 2 L |
|---|---|
| Bore | 3.2283" |
| Stroke | 3.7244" |
| Cylinders | 4 |
| Configuration | I4 |
| Compression ratio | 11.1:1 |
| Bore/stroke ratio | 0.867 |
| Fuel type | gas |
|---|---|
| Advertised HP | 201 hp |
| Years | 2025 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 2025 | B48A20M2 net | 201 @ 5000 | 221 lb-ft @ 1450 | 11.1:1 |
Factory specification sheet.
| Bore/stroke character | 0.867 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,724 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 30.5 ci |
| Static compression | 11.1:1 — high enough that pump premium or better is normally required |
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1 factory vehicle, 2025. Each year opens that model's engine table.