BMW S63 engine explained: the twin-turbo V8 of modern M cars

The BMW S63 is the twin-turbo V8 that has powered BMW's biggest M cars for more than a decade. It appeared first in the X5 M and X6 M in 2009 and later powered the M5, M6, M8 and their Competition versions.

Its unusual design places the turbochargers inside the V of the engine, which gives a quick response and huge torque. In this article we explain how the S63 works, the different versions and power outputs, its known issues and the maintenance it needs to stay healthy.

Where the S63 comes from

The S63 is based on the N63, a 4.4-litre twin-turbo V8 used in regular BMW models such as the 550i, 750i and X5 xDrive50i. BMW M changed many parts for higher power, better cooling and sustained high loads.

The first S63 appeared in the E70 X5 M and E71 X6 M in 2009. It marked a big change for BMW M, which had previously preferred high-revving naturally aspirated engines such as the V8 of the E92 M3 and the V10 of the E60 M5. Our article on BMW engine codes explains how names such as S63 work.

The hot-V design of the BMW S63

In most V8 engines, the exhaust manifolds sit on the outside of the cylinder banks. In the BMW S63, the layout is reversed: the exhaust side faces inwards, and the two turbochargers sit inside the V between the cylinder banks. This is often called a hot-V design.

The benefits include:

• Short exhaust paths, so the turbochargers receive exhaust energy quickly, improving response.
• A compact engine package.
• Strong torque from low engine speeds.

The downside is that a lot of heat is concentrated in the centre of the engine, which places high demands on cooling, hoses, seals and oil. That is why the S63 uses an extensive cooling system with several radiators.

Versions and power outputs

The S63 has been updated several times. The main versions include:

• First generation: in the X5 M and X6 M (E70, E71), with 555 hp.
• F10 M5 and F12/F13/F06 M6: a revised version with 560 hp, later more with the Competition package.
• F85 X5 M and F86 X6 M: 575 hp.
• F90 M5 and M8: a heavily updated version with 600 hp, and 625 hp in the Competition models, with M xDrive.
• F95 X5 M and F96 X6 M: 600 hp and 625 hp in Competition form.
• Special models such as the M5 CS with even more power.

Exact outputs depend on the market and model year. Our articles on the BMW M6 history, the F10 M5 buying guide and the X5 M and X6 M history explain the cars that use this engine.

Known issues

The S63 is powerful and generally strong, but owners should be aware of these points, especially on earlier versions:

• Oil consumption: some consumption is normal, but early engines in particular could use more oil. Our article on BMW oil consumption explains what is normal.
• Cooling and coolant leaks: the hot-V layout puts stress on hoses, coolant pipes and pumps.
• Turbocharger oil and coolant lines: leaks can appear around the hot area in the centre of the engine.
• Injectors and ignition coils: misfires can come from these parts. Our article on BMW spark plugs and ignition coils explains intervals.
• Valve stem seals: on some versions, wear can increase oil consumption and smoke at start-up.
• Battery and electronics: these cars have complex electrical systems that depend on a healthy battery.

Later versions of the S63 received many updates that addressed several of these issues.

Maintenance that matters

To keep a BMW S63 healthy:

• Change the oil frequently with the correct approved oil. Many specialists recommend shorter intervals than the maximum. Our article on BMW M engine oil explains the requirements.
• Warm up the engine gently and let it cool after hard driving. Our article on BMW turbo problems explains why turbos need care.
• Maintain the cooling system and fix leaks quickly.
• Replace spark plugs at the correct intervals, or earlier on tuned cars.
• Monitor oil consumption and note any changes.
• Keep software up to date through a BMW service partner.

Records of this work are important when you sell the car.

Tuning the S63

The S63 responds strongly to tuning, and many owners increase power with software. Remember that:

• Higher power increases stress on the engine, gearbox, cooling system and brakes.
• Modifications must be legal in your country and declared to your insurer.
• Warranty can be affected.

A well-maintained standard engine with full history is usually the safest choice for long-term reliability.

The successor: S68

BMW introduced a new V8, the S68, in models such as the XM and the latest M5. It continues the twin-turbo V8 concept, but it is designed to work with hybrid technology. Our article on the BMW XM explains how the S68 works with an electric motor.

The S63 remains one of the most important engines in BMW M history. It brought M cars into the turbo era and delivered enormous performance for more than a decade.

BMW S63 engine at a glance

Item	Details
Layout	4.4-litre V8, twin-turbo
Design	Hot-V with turbos inside the V
First used	2009 in the X5 M and X6 M
Power range	From 555 hp to 625 hp and more in special models
Main models	M5, M6, M8, X5 M, X6 M
Key checks	Oil consumption, cooling, leaks, injectors
Successor	S68 V8 for hybrid M models

Frequently asked questions

Which cars have the BMW S63 engine?

The X5 M, X6 M, F10 and F90 M5, F12/F13/F06 M6, M8 and their Competition versions.

Is the BMW S63 reliable?

Later versions are generally strong when maintained. Earlier versions need careful attention to oil consumption, cooling and leaks.

What is a hot-V engine?

An engine with the turbochargers placed inside the V between the cylinder banks, for short exhaust paths and quick response.

How much power does the S63 make?

From 555 hp in the first version to 625 hp in Competition models, and more in special editions.

Sources

• BMW Group PressClub – BMW M5, M8 and X5 M press kits
• BMW M GmbH – official model information