See other engines in this family
Audi ABZ, AKB, AUX specs: 4.2L (256.3 ci) 8-cylinder, 84.5 x 93 mm (3.3268 x 3.6614 in) bore and stroke, 10.8:1 compression. Rated 300 hp. DOHC.
The Audi ABZ, AKB, AUX is undersquare — the 3.6614" stroke exceeds the 3.3268" bore by 9.1% — a layout that trades peak RPM for leverage and torque low in the range. The 3.6614" 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 8 cylinders displaces 32.0 ci (525 cc).
10.8:1 on aluminum heads is in the range that usually runs on pump premium; aluminum sheds heat faster than iron, which makes the same number a little more forgiving.
It is one of 11 engines in the EA824 family, sitting between the 244.1 ci and 317.4 ci members. Factory fitments include the Audi A8 (D2), Audi S6 (C5).
| Displacement | 256.3 ci / 4.2 L |
|---|---|
| Bore | 3.3268" |
| Stroke | 3.6614" |
| Cylinders | 8 |
| Compression ratio | 10.8:1 |
| Bore/stroke ratio | 0.909 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 300 hp |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 1997 | ABZ net | 300 @ 6000 | 295 lb-ft @ 3300 | 10.8:1 |
| 1998 | ABZ net | 300 @ 6000 | 295 lb-ft @ 3300 | 10.8:1 |
| 1999 | ABZ net | 300 @ 6000 | 295 lb-ft @ 3300 | 10.8:1 |
Factory specification sheet.
| Bore/stroke character | 0.909 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,661 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 32.0 ci |
| Static compression | 10.8:1 — in the range that usually runs on pump premium |
Each link opens the calculator with this engine's specs already filled in.