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Crankcase, Cylinder Head and Valve Timing Components
The crankcase was taken from the N63.
In view of the high ignition pressures of the S63, the pistons were upgraded accordingly.
The interior structure of the crankcase ventilation system has been adapted in terms of
the oil separator and control valve (similar to S85).
Cylinder Head
The cylinder head has been adapted to accommodate the higher thermal and mechanical
loads, the modified turbochargers (ATL) and exhaust manifold as well as the increased
transverse dynamics of the vehicle.
The following changes have been made to the cylinder heads compared to the N63:
• The S63 cylinder heads are made from a higher grade alloy
• Adapted bolt pattern arrangement for the new exhaust manifold
• The exhaust camshafts are new and specific to the S63
Other changes to the top of the engine include the newly designed oil filler neck and its
new location as well as the redesigned thermostat housing.
Note: It is important to note that the rigidity of the engine mounts on the S63
has been adapted toMspecific requirements.
E70/E71Mtiming gear
The timing components have been adopted from the N63 engine.
The following changes have been made:
• The cam timing has been adapted accordingly (see Technical Data)
• The exhaust camshafts are new components, specific to the S63.
Exhaust System
ExhaustManifold
On the N63, a single-flow, cast exhaust manifold per cylinder bank is assigned to each
exhaust turbocharger (cyl. 1–4 and cyl. 5–8).
The S63 is fitted with a four-flow, air gap insulated tuned pulse exhaust manifold that
connects both cylinder banks. In an ideal configuration, the exhaust gas pulses from
cylinders 1/6 and 4/7 are fed to the turbocharger installed over the right bank (cyl.1-4)
and the exhaust gas pulses from cylinders 2/8 and 3/5 are fed to the turbocharger
installed over the left bank (cyl. 5-8).
This design creates a spacing of 360° of crankshaft angle between the two exhaust
cycles within the exhaust flute that feeds each twin scroll turbocharger turbine. The effective
utilization of the exhaust gas energy delivers optimum de-throttling, ideal response
characteristics and minimizes turbo lag.
Corrugated pipes combined with sliding seat flanges connect the exhaust ports from
both banks within the center of the manifold outer shell to compensate for thermomechanical
expansion and contraction. (See below)
The specially designed exhaust manifold connects each of the 8 cylinders in sequence
according to the exhaust pulses in the firing order. This delivers a uniform flow of exhaust
gas to the turbochargers which improves volumetric efficiency by promoting cylinder
scavenging.
Every 180° of crankshaft rotation, one exhaust gas pulse is fed to each turbocharger over
the entire ignition sequence (1–5–4–8–6–3–7–2).
This highly efficient charging concept achieves optimum energy transmission of the
exhaust flow to the turbine blades of the turbochargers. The result is the fastest and
most direct response characteristics of any turbo engine worldwide. The innovative
technology is patented by BMW and therefore represents a unique selling point over
the competition.
Advantages of the Twin-scroll Turbo System
The response characteristics of the exhaust turbochargers are enhanced when compared
to the N63. The S63 turbocharger turbines are fed through two separate channels within
the turbine housing (highlighted red in the graphic above). Each of these channels or
“scrolls” is always fed by the exhaust pulses from the same two cylinders.
The layout and cross sections of the turbine impeller and compressor wheels have been
correspondingly adapted and are designed for the maximum exhaust inlet operating temperature
of 1020° C (1868° F).
The diverter valves are now integrated in the charge air line and have a hose connection
to the turbocharger compressor inlet side (See the graphic on the next page).
Catalytic converters and oxygen sensors are the same as in the N63 with the cable routing
of the oxygen sensors adapted accordingly to the new engine.
Intake Silencer (AGD)
To enhance air flow to the engine while taking
pedestrian protection into consideration, the
intake silencer has been redesigned and fixed
to the body directly in front of the engine (on
N63 its fixed to the engine).
Two activated carbon filters prevent pollutants
(that could stem from the engine) from entering
the intake system when the engine is not
in operation, complying with corresponding
emission requirements.
US models use an intake silencer with an
integrated snow valve and additional activated
carbon filter mesh.
SnowValve
The snow valve is a filter bypass valve that is opened by engine vacuum. It allows continued
engine operation (at greatly reduced power output) if necessary, should the air cleaner
be iced up or closed off with packed snow in extreme wheather conditions
Cooling Systems
As in the series production X6 (xDrive50i) the X5/X6 M have two cooling systems, the
main engine cooling system and a low temperature cooling system dedicated to intake
charge air cooling (turbo intercooling).
The following components have been adopted from the N63 and are common with
series production E71 vehicles:
• The low temperature system heat exchanger for the intercoolers
• Air conditioning condenser
• Power steering oil cooler
• The standalone auxiliary radiator
The expansion tank for the main engine cooling system was taken from the E70.
New and Adapted Cooling Components
The main coolant radiator takes up the same package space as in the E71 but has a
winglet tubing design, for increased surface area. It no longer contains the integrated low
temperature area for the transmission oil-to-coolant heat exchanger.
The engine oil cooler has been adapted to the higher engine output by increasing the
core depth from 30 mm to 45 mm.
The charge air (low temperature) cooling system has an additional intercooler heat
exchanger installed in series, a second auxiliary water pump and a new expansion tank.
The length of the engine intercoolers (LLK) has been increased from 130 mm to 160
mm. The measuring range of the boost pressure sensors at the intercooler outlet has also
increased to 4 bar.
The transmission oil heat exchanger has been adapted to the higher engine output by
increasing the number of plates from 23 to 31.
Transmission
With the M Sport automatic transmission 6HP26S the customer is able to enjoy spontaneous
gearshifts and a more stable control of the torque converter lock-up clutch.
To effectively absorb rotational irregularities in the drive train and achieve the best possible
reduction of the slip at the converter lock-up clutch, a double-damper torque converter
is installed. A single-damper torque converter design is used in the 6HP26TU of the
E71 xDrive50i.
The spring characteristics in the double-damper converter are especially designed for the
increased power and torque of the S63 engine. The 6HP26S internal components have
also been adapted to the maximum engine speed of 6800 rpm.
The plastic transmission oil pan has been replaced with an aluminum version. The air flow
to the transmission has been enhanced and the opening point of the transmission oil
thermostat has been lowered.
The gear ratio is identical to that of the series production 6HP26TU transmission.
Transmission Control
The electronic transmission control unit (EGS) for the 6HP26S, is integrated into the
transmission case as on the series production model.
The transmission control software is adapted to M specific requirements.
The transmission now features even shorter shift times in manual mode, ensured by a
new type of torque reduction system involving cylinder cutout. This feature along with
the short axle transmission ratio emphasize the sporty characteristics of the vehicle.
A special M shifting program ensures quick and precise gear changes and enhances
throttle response throughout the three driving modes.
Front Axle
Springs and Struts
Front springs are series production E71 with EDC. Shock absorbers are also E71 N63
with EDC but with piston rods adapted to the newly designed strut mounts. Damper
hardness and characteristic were specially adapted to M requirements and suspension
setup.
Rear Axle
The rubber mounts between the body and rear axle carrier are adapted in terms of their
rigidity to M specific requirements.
Springs and Struts
New strut mounts with specially adapted internal rubber section are installed. The air
springs are new and have been adapted to the strut mount, lower vehicle height and M
specific tuning. The air springs are based on the E71 N63 EDC but with layout for M
suspension setup. The shock absorbers are also based on the E71 N63 EDC, with the
piston rod adapted to the new strut mount. Damper hardness and characteristic were
especially adapted to M requirements.
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