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Audi AMU / BEA specs: 1.8L (107 ci) 4-cylinder, 81 x 86.4 mm (3.1890 x 3.4016 in) bore and stroke, 9:1 compression. Built 2001–2006. Used in the Audi TT.
The Audi AMU / BEA is undersquare — the 3.4016" stroke exceeds the 3.189" bore by 6.3% — a layout that trades peak RPM for leverage and torque low in the range. The 3.4016" stroke does not reach 4,000 ft/min of mean piston speed until about 7,050 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 26.8 ci (438 cc).
9:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 3 engines in the Audi 107ci family, all of them 107 ci — the differences between them are in compression, heads and rating, not displacement. 6 factory variants share these dimensions across 2001–2006.
| Displacement | 107 ci / 1.8 L |
|---|---|
| Bore | 3.189" |
| Stroke | 3.4016" |
| Cylinders | 4 |
| Configuration | I4 |
| Compression ratio | 9:1 * |
| Bore/stroke ratio | 0.938 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | gas |
|---|---|
| Years | 2001–2006 |
| Bore/stroke character | 0.938 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,402 ft/min — conservative for a street engine |
| Displacement per cylinder | 26.8 ci |
| Static compression | 9:1 — 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 |
|---|---|---|
| 2001 | — | AMU / BEA |
| 2002 | — | AMU / BEA |
| 2003 | — | AMU / BEA |
| 2004 | — | AMU / BEA |
| 2005 | — | AMU / BEA |
| 2006 | — | AMU / BEA |
1 factory vehicle, 2001–2006. Each year opens that model's engine table.