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BMW N63B44 specs: 4.4L (268 ci) 8-cylinder, 89 x 88.3 mm (3.5039 x 3.4764 in) bore and stroke. Rated 400-523 hp, 2009–2023. Used in the BMW 7 Series.
The BMW N63B44 is close to square: 3.5039" bore against 3.4764" stroke, within 0.8%, which splits the difference between a high-revving layout and a torque layout. The 3.4764" stroke puts mean piston speed at 4,000 ft/min around 6,900 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 33.5 ci (549 cc).
It is one of 12 engines in the BMW 268ci family, all of them 268 ci — the differences between them are in compression, heads and rating, not displacement. 21 factory variants share these dimensions, rated from 400 to 523 hp across 2009–2023.
| Displacement | 268 ci / 4.4 L |
|---|---|
| Bore | 3.5039" |
| Stroke | 3.4764" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 10–10.5:1 (published figures vary) |
| Bore/stroke ratio | 1.008 |
| Fuel type | gas |
|---|---|
| Advertised HP | 400–523 hp |
| Years | 2009–2023 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 2011 | N63B44 net | 400 @ 5500 | 450 lb-ft @ 1800 | 10:1 |
| 2012 | N63B44 net | 400 @ 5500 | 450 lb-ft @ 1800 | 10:1 |
| 2013 | N63B44 net | 400 @ 5500 | 450 lb-ft @ 1800 | 10:1 |
| 2018 | N63B44M3 net | 456 @ 5250 | 479 lb-ft @ 1500 | 10.5:1 |
| 2019 | N63B44M3 net | 456 @ 5250 | 479 lb-ft @ 1500 | 10.5:1 |
| 2020 | N63B44M3 net | 456 @ 5250 | 479 lb-ft @ 1500 | 10.5:1 |
| 2020 | N63B44T3 net | 523 @ 5500 | 553 lb-ft @ 1800 | 10.5:1 |
| 2021 | N63B44T3 net | 523 @ 5500 | 553 lb-ft @ 1800 | 10.5:1 |
| 2022 | N63B44T3 net | 523 @ 5500 | 553 lb-ft @ 1800 | 10.5:1 |
| 2023 | N63B44T3 net | 523 @ 5500 | 553 lb-ft @ 1800 | 10.5:1 |
Factory specification sheet.
| Bore/stroke character | 1.008 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,476 ft/min — conservative for a street engine |
| Displacement per cylinder | 33.5 ci |
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 |
|---|---|---|
| 2009 | — | N63B44 |
| 2010 | — | N63B44 |
| 2011 | — | N63B44 |
| 2011 | 400 hp | N63B44 |
| 2012 | — | N63B44 |
| 2012 | 400 hp | N63B44 |
| 2013 | — | N63B44 |
| 2013 | 400 hp | N63B44 |
| 2014 | — | N63B44 |
| 2015 | — | N63B44 |
| 2016 | — | N63B44 |
| 2017 | — | N63B44 |
| 2018 | — | N63B44 |
| 2018 | 456 hp | N63B44 |
| 2019 | — | N63B44 |
| 2019 | 456 hp | N63B44 |
| 2020 | 456 hp | N63B44 |
| 2020 | 523 hp | N63B44 |
| 2021 | 523 hp | N63B44 |
| 2022 | 523 hp | N63B44 |
| 2023 | 523 hp | N63B44 |
4 factory vehicles, 2009–2023. Each year opens that model's engine table.