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Toyota B48B20 specs: 2.0L (121.9 ci) 4-cylinder, 82 x 94.6 mm (3.2283 x 3.7244 in) bore and stroke, 10.2:1 compression. Used in the Toyota Supra.
The Toyota B48B20 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 (499 cc).
10.2:1 is in the range that usually runs on pump premium.
It is one of 4 engines in the BMW B48/B58 (Supra) family, the smallest at 121.9 ci.
| Displacement | 121.9 ci / 2 L |
|---|---|
| Bore | 3.2283" |
| Stroke | 3.7244" |
| Cylinders | 4 |
| Compression ratio | 10.2:1 |
| Bore/stroke ratio | 0.867 |
| Fuel type | gas |
|---|
| 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 | 10.2:1 — in the range that usually runs on pump premium |
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1 factory vehicle, 2021–2024. Each year opens that model's engine table.