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Porsche MDB.CB specs: 3.7L (228.5 ci) 6-cylinder, 102 x 76.4 mm (4.0157 x 3.0079 in) bore and stroke, 8.7:1 compression. Rated 543-640 hp, 2021–2025.
The Porsche MDB.CB is oversquare — the 4.0157" bore exceeds the 3.0079" stroke by 33.5% — a layout that favors airflow and RPM over leverage at the crank. The 3.0079" stroke does not reach 4,000 ft/min of mean piston speed until about 8,000 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 38.1 ci (624 cc).
8.7:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 9 engines in the 9A2 Evo family, sitting between the 121.3 ci and 243.9 ci members. 11 factory variants share these dimensions, rated from 543 to 640 hp across 2021–2025.
| Displacement | 228.5 ci / 3.7 L |
|---|---|
| Bore | 4.0157" |
| Stroke | 3.0079" |
| Cylinders | 6 |
| Compression ratio | 8.7:1 * |
| Bore/stroke ratio | 1.335 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | gas |
|---|---|
| Advertised HP | 543–640 hp |
| Years | 2021–2025 |
| Bore/stroke character | 1.335 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,008 ft/min — conservative for a street engine |
| Displacement per cylinder | 38.1 ci |
| Static compression | 8.7:1 — 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 |
|---|---|---|
| 2021 | 572 hp | MDB.CB |
| 2021 | 640 hp | MDB.CB |
| 2022 | 572 hp | MDB.CB |
| 2022 | 640 hp | MDB.CB |
| 2023 | 543 hp | MDB.CB |
| 2023 | 572 hp | MDB.CB |
| 2023 | 640 hp | MDB.CB |
| 2024 | 572 hp | MDB.CB |
| 2024 | 640 hp | MDB.CB |
| 2025 | 572 hp | MDB.CB |
| 2025 | 640 hp | MDB.CB |
1 factory vehicle, 2021–2025. Each year opens that model's engine table.