BMW S63B44 engine code explained
S63B44 is the full code for the M Division's version of the hot-V twin-turbo V8: the engine in the E70 / E71 X5 M and X6 M, the F10 M5 and F1x M6, the F85 / F86 X5 M and X6 M, and the F90 M5, F9x M8 and F95 / F96 X5 M and X6 M. Four suffixes mark four generations, from 547 bhp to 626 bhp. It inherits the N63's coolant-pipe design and adds the M engine's rod-bearing preventative.
Quick answer
The S63B44 is the 4.4-litre V8 twin-turbo M engine petrol of the BMW S63 family, built 2009-2024. Bimmer.AI scores the family 6 / 10: a sound used buy provided the known weak points are documented. The tables below give every output tier and sticker letter BMW used on this stem and which cars got them; the failure table is the same one that powers the S63 family guide.
How to read S63B44
| Part of the code | Meaning |
|---|---|
| S | BMW M GmbH (M Division) engine |
| 63 | engine family number within the S-series |
| B | petrol, longitudinal (rear-drive platform: 1 to 8 Series, X3 to X7, Z4) |
| 44 | displacement in tenths of a litre: 4.4 litres |
| K / U / M / O / T / S + digit | output tier and revision, appended in BMW's internal naming (for example S63B44O1) |
| A / B / C / D | parts-catalogue engine version printed on the engine cover sticker (for example S63B44A) |
S63B44 output tiers and which cars have them
| Code | Output | Cars | Notes |
|---|---|---|---|
| S63B44O0 | 547 bhp (original S63) | X5 M (E70 2009-2013), X6 M (E71 2009-2014) | First hot-V M V8 |
| S63B44T0 | 552 bhp, 567 bhp (Competition), 592 bhp (30 Jahre) | M5 (F10 2011-2016), M6 (F06 / F12 / F13 2012-2018) | S63TU with Valvetronic; the F10 M5 engine |
| S63B44T2 | 567 bhp | X5 M (F85 2014-2018), X6 M (F86 2014-2019) | SUV-specific cooling |
| S63B44T4 | 592 bhp (M5, M8), 616 bhp (Competition), 626 bhp (M5 CS, X5 M / X6 M Competition) | M5 (F90 2018-2024), M8 (F91 / F92 / F93 2019 on), X5 M (F95 2020-2023), X6 M (F96 2020-2023) | Current generation until the S68 hybrid M5 |
S63B44 sticker letters: S63B44A, S63B44B, S63B44C
Whatever the letter, an S63 needs the same two items priced in: rod bearings (£2,000 to £3,500, the mandatory M V8 preventative at 50,000 to 70,000 miles) and the coolant transfer pipe in the valley (£2,000 to £3,500). Add the charge-pipe upgrade and hot-V battery wear. A car with all four documented is a very different purchase from one with none.
| Sticker code | What it denotes |
|---|---|
| S63B44A | Original S63 (X5 M / X6 M E70 / E71). |
| S63B44B | S63TU (F10 M5, F1x M6, F85 / F86 X5 M / X6 M). |
| S63B44C | F90 M5 / F9x M8 generation. |
Known problems on every S63B44
Failure data is held once, per engine family, so this table is identical to the BMW S63 guide. Cost ranges are indicative UK figures.
| Failure mode | Severity | Frequency | Typical onset | UK repair range |
|---|---|---|---|---|
| Rod bearing wear | Catastrophic | Common | 40 to 100k mi | £2,000 to £3,500 |
| Coolant transfer pipe (inherited from N63) | Moderate | Common | 80 to 150k mi | £2,000 to £3,500 |
| OEM plastic charge pipe | Moderate | Common | 30 to 100k mi | £200 to £500 |
| Battery wear from hot-V heat | Mild | Very common | 20 to 80k mi | £250 to £400 |
| Intake valve carbon buildup | Moderate | Common | 50 to 100k mi | £500 to £900 |
Long-term verdict
M-engine derivative of the N63 architecture. Inherits the coolant transfer pipe pattern (less common on M-cars because they tend to get better service); adds rod-bearing concerns similar to other M-engines. Preventative rod-bearing service and coolant pipe inspection are the defining maintenance items. With both addressed and a documented M-service history, the S63 is genuinely robust for an M V8. M5 F10 and X5M / X6M F85 / F86 are the cars where this engine has the largest used presence; F90 M5 is still mostly under warranty in 2026.
Check a specific S63B44 listing
Paste any BMW S63 listing, VIN or registration. Bimmer.AI identifies the exact engine and returns the buyer report in 30 seconds.
Run a Bimmer.AI buyer report →Bimmer.AI is designed to help you identify BMW-specific buyer risks before you travel, negotiate, or pay for an inspection. It does not replace a physical inspection by a qualified mechanic, a legal vehicle-history check (e.g. HPI Check), or independent verification of finance, stolen, or write-off status. Repair-cost ranges are indicative UK figures that vary by region, specialist, parts supply, and labour rates.
Frequently asked questions
S63B44T0 vs S63B44T4: F10 M5 or F90 M5?
The T4 (F90 M5, 2018 onwards) adds revised turbos, higher fuel pressure, a new cooling package and 592 to 626 bhp, and drives through an 8-speed automatic and M xDrive rather than the F10's 7-speed DCT. Mechanically the rod-bearing and coolant-pipe conversations apply to both; the T4 has more cars still under warranty. The F10 M5 is the value buy at roughly half the money; the F90 is the more complete car.
Do S63B44 rod bearings really need replacing?
Treat it as a scheduled service on any S63 past 50,000 miles, especially tracked or tuned cars: £2,000 to £3,500 at a specialist for bearings and bolts, sometimes with an oil analysis first. It is the same preventative culture as the S65 and S85, and the market prices it in. A car with receipts is worth the premium.
Which BMWs have the S63B44 engine?
The S63B44 went into the following cars, by output tier. S63B44O0 (547 bhp (original S63)): X5 M (E70 2009-2013), X6 M (E71 2009-2014); S63B44T0 (552 bhp, 567 bhp (Competition), 592 bhp (30 Jahre)): M5 (F10 2011-2016), M6 (F06 / F12 / F13 2012-2018); S63B44T2 (567 bhp): X5 M (F85 2014-2018), X6 M (F86 2014-2019); S63B44T4 (592 bhp (M5, M8), 616 bhp (Competition), 626 bhp (M5 CS, X5 M / X6 M Competition)): M5 (F90 2018-2024), M8 (F91 / F92 / F93 2019 on), X5 M (F95 2020-2023), X6 M (F96 2020-2023). The two-letter family badge is S63; any listing that quotes the family code is talking about one of these.
Is the BMW S63B44 reliable?
Bimmer.AI scores the S63 family 6 out of 10, which makes the S63B44 a sound used buy provided the known weak points are documented. M-engine derivative of the N63 architecture. Inherits the coolant transfer pipe pattern (less common on M-cars because they tend to get better service); adds rod-bearing concerns similar to other M-engines. Preventative rod-bearing service and coolant pipe inspection are the defining maintenance items. With both addressed and a documented M-service history, the S63 is genuinely robust for an M V8. M5 F10 and X5M / X6M F85 / F86 are the cars where this engine has the largest used presence; F90 M5 is still mostly under warranty in 2026.
What does S63B44 mean?
S is the BMW M GmbH (M Division) engine, 63 is the family number, B means petrol, longitudinal (rear-drive platform: 1 to 8 Series, X3 to X7, Z4), and 44 is the displacement in tenths of a litre (4.4 litres). BMW appends an output tier and revision (K, U, M, O, T or S plus a digit) in its own naming, and the parts catalogue adds a version letter (A, B, C) that is what you see on the engine cover.