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Audi AUK / BKH specs: 3.2L (191 ci) 6-cylinder, 84.5 x 92.8 mm (3.3268 x 3.6535 in) bore and stroke, 12.5:1 compression. Rated 255 hp, 2005–2009.
The Audi AUK / BKH is undersquare — the 3.6535" stroke exceeds the 3.3268" bore by 8.9% — a layout that trades peak RPM for leverage and torque low in the range. The 3.6535" stroke puts mean piston speed at 4,000 ft/min around 6,550 RPM, which is where a production bottom end is generally considered at its limit. Each of the 6 cylinders displaces 31.8 ci (522 cc).
12.5:1 is high for a production gasoline engine; running a ratio like that on pump fuel depends on chamber design and fuel delivery rather than the number alone.
5 factory variants share these dimensions, rated at 255 hp across 2005–2009.
| Displacement | 191 ci / 3.2 L |
|---|---|
| Bore | 3.3268" |
| Stroke | 3.6535" |
| Cylinders | 6 |
| Configuration | V6 |
| Compression ratio | 12.5:1 |
| Bore/stroke ratio | 0.911 |
| Fuel type | gas |
|---|---|
| Firing order | 1-4-3-6-2-5 |
| Advertised HP | 255 hp |
| Years | 2005–2009 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 2005 | AUK / BKH net | 255 @ 6500 | 243 lb-ft @ 3250 | 12.5:1 |
| 2006 | AUK / BKH net | 255 @ 6500 | 243 lb-ft @ 3250 | 12.5:1 |
| 2007 | AUK / BKH net | 255 @ 6500 | 243 lb-ft @ 3250 | 12.5:1 |
| 2008 | AUK / BKH net | 255 @ 6500 | 243 lb-ft @ 3250 | 12.5:1 |
| 2009 | AUK / BKH net | 255 @ 6500 | 243 lb-ft @ 3250 | 12.5:1 |
Factory specification sheet.
| Bore/stroke character | 0.911 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,654 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 31.8 ci |
| Static compression | 12.5:1 — high enough that pump premium or better is normally required |
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 |
|---|---|---|
| 2005 | 255 hp | AUK / BKH |
| 2006 | 255 hp | AUK / BKH |
| 2007 | 255 hp | AUK / BKH |
| 2008 | 255 hp | AUK / BKH |
| 2009 | 255 hp | AUK / BKH |
1 factory vehicle, 2005–2009. Each year opens that model's engine table.