Audi 4.2-litre V8 FSI Manual

377
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specifications subject to
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AUDI AG
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AUDI AG
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Technical status: 03/06
Printed in Germany
A06.5S00.23.20
Audi 4.2-litre V8 FSI engine
Self-Study Programme 377
Vorsprung durch Technik www.audi.de
Service Training

377_045
Special features of the current Audi vee engine family are the 90-degree included angle between the
cylinder banks and the spacing of 90 mm between the cylinders.
The first member of the family was the 3.2-litre V6 FSI engine. The 4.2-litre V8 FSI engine is also a member
of this family.
It is available in two versions - a comfort-oriented basic version (used for the first time in the Audi Q7) and
a sporty high-revving version for the new RS4. A V10 engine with 5.2 litres of displacement will also be
available.
Like the RS4 engine, the V8 in the Q7 has FSI direct injection, which – following five victories in the
Audi R8 Le Mans racing car – is now being introduced in a production eight-cylinder model.
The V8 was retuned for use in the Audi Q7. A fuller torque curve up to nominal speed and spontaneous
response – these are the characteristics of this new engine.
The engine excels not only with its dominant power output and high maximum torque. The resultant
driving performance is excellent, even in the face of tough competition.
RS4 high-revving engine

Table of contents
Engine mechanicals
Oil circulation system
Cooling system
Air circulation system
Cranktrain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Crankcase ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Chain drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Drive, ancillary units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Cylinder head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Oil pump and oil filter module. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Oil pan Audi RS4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Oil circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Cooling system in Audi Q7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Cooling system in Audi RS4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Air intake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Intake manifold flaps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Vacuum hoses in the Audi RS4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Vacuum hoses in the Audi Q7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Engine management
System overview, Audi Q7 (Bosch MED 9.1.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
System overview, Audi RS4 (Bosch MED 9.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Operating modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
CAN data bus interfaces (powertrain CAN data bus) in the Audi Q7. . . . . . . . . 42
CAN data bus interfaces (powertrain CAN data bus) in the Audi RS4 . . . . . . . 43
Start mode of the Audi RS4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Sport mode of the Audi RS4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
The self-study programme teaches the basics of the design and function of new models,
new automotive components or new technologies.
The self-study programme is not a Repair Manual!
All values given are intended as a guideline only and refer
to the software version valid at the time of publication of the SSP.
For maintenance and repair work, always refer to the current technical literature.
NoteReference
Exhaust system
Exhaust system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Exhaust flap control in the Audi RS4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Secondary air system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Fuel system in the Audi Q7/RS4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Fuel system

6
The 4.2-litre V8 FSI engine is supplied in the new
Audi Q7, Audi A6, Audi A8 and in the RS4.
Note
The technical descriptions of this engine refer
mainly to the V8 basic engine in the Audi Q7
and the high-revving engine in the Audi RS4.
377_003
Introduction
The following main objectives were set for
the development of the Q7 engine:
– High specific engine power:
257 kW/350 bhp out of 4.2 litres (15 bhp more
than MPI engines)
– High torque: 440 Nm out of 4.2 litres
– Reduction of fuel consumption by approx. 5 %
(~360 g/kWh at 2000 rpm and 2 bar)
– Short and compact design
– Modular engine concept based on V6 FSI engine
for V8 and V10 FSI (synergy)
– High idling quality
– High standard of comfort with regard to
acoustics and running quality
– Low engine weight
– Off-road capability of Audi Q7 engine
Q7 engine

7
377_002
Technical features
– Petrol direct injection
– Homogeneous-charge mode
– Roller cam followers with hydraulic backlash
compensation
– Flywheel-side chain drives for camshafts and
ancillary units
– Variable camshaft adjustment for intake and
exhaust camshafts
– Two-stage magnesium variable inlet manifold
with integrated tumble flap (not fitted in RS4)
– Drive-by-wire throttle control
– for compliance with exhaust emission standards
EU IV/LEV II
The main technical differences between the base
engine and the high-revving engine lie in the
following modules:
– Cranktrain
– Timing gear
– Cylinder head
– Oil supply
– Engine cooling
– Intake path
– Exhaust system
– Engine management
For an exact description of the differences, please
refer to the relevant section.
RS4 engine

8
160
200
240
280
320
80
kW
Nm
460
300
380
420
20000 5000 7000 9000
Introduction
Torque/power curve
Max. torque in Nm
V8 FSI basic engine in Q7
V8 FSI high-revving engine in RS4
Max. power output in kW
V8 FSI basic engine in Q7
V8 FSI high-revving engine in RS4
Engine speed in RPM
Specifications
Q7 RS4
Engine code BAR BNS
Type of engine V8 90° vee angle 4V FSI
Displacement in cm34163
Max. power output in kW (bhp) 257 (350) at 6800 rpm 309 (420) at 7800 rpm
Max. torque in Nm 440 at ~3500 rpm 430 at 5500 rpm
Number of valves per cylinder 4
Bore in mm 84.5
Stroke in mm 92.8
Compression ratio ~12.5/-0.4 : 1
Firing order 1–5–4–8–6–3–7–2
Engine weight in kg approx. 198* approx. 212**
Engine management Bosch MED 9.1.1 Bosch 2x MED 9.1
Fuel grade 98 / 95 RON
Exhaust emission standard EU IV/LEV II
* with automatic transmission
** manual gearbox including clutch and dual-mass flywheel

9
377_006
*Aluminium alloys are classed as hypoeutectic or
hypereutectic, depending on their silicon content.
"Alusil" has a hypereutectic silicon content of 16 to
18 % so that primary silicon is precicipated on
solidification of the molten metal.
A multistage honing process is applied. The silicon
grains in the cylinderbores in the form of micro-
scopically small, very hard particles are stripped to
give the necessary wear resistance of the cylinder
surfaces for the piston and piston rings.
– Cylinder spacing: 90 mm
– Cylinder bank offset: 18.5 mm
– Overall engine length: 464 mm
– Cylinder block height: 228mm
Engine mechanicals
Cranktrain
Cylinder block
The cylinder crankcase has a closed-deck design.
The closed-deck design is stronger than the open-
deck design.
In an open-deck cylinder block, the water jacket for
cooling the cylinders is open at the top.
The cylinder crankcase is made of a low-pressure
gravity diecast aluminium-silicon alloy, is
hypereutectic* and has a silicon content of 17 %
(AlSi17Cu4Mg).
The cylinder crankcase underwent special heat
treatment in order to increase its strength.
The cylinder liners are mechanically stripped.
The cylinder crankcase of the high-revving engine
was machined to higher specifications due to the
higher stresses in this component. To minimise
warping of the cylinder manifolds, the crankcase is
honed under stress. For this purpose, a honing
template is attached to the crankcase before the
honing process in order to simulate the warping of
the bolted cylinder manifold.
The cylinder crankcase lower section (bedplate
bearing cross-member) is made of aluminium with
press-fitted iron main bearing covers made of grade
50 nodular cast iron. It is centred using centring
pins, sealed with liquid sealant and bolted to the
cylinder crankcase.
The main bearing is symmetrically to the centre of
the main bearing attached by four bolts.
The bedplate type design provides high stability.
The bedplate has the same stabilising effect as a
ladder frame.
Cylinder crankcase bottom section
Press-fitted main bearing
Cylinder crankcase

10
377_035
Engine mechanicals
Crankshaft
The crankshaft runs on five bearings and is made of
high-alloy tempering steel (42CrMoS4). It is 90°
cranked and has no conrod journal offset.
The vibration damper is a vulcanised single-mass
damper with unbalance.
– Main bearing: Ø 65 mm
– Main bearing width: 18.5 mm
– Big-end bearing: Ø 54 mm
– Big-end bearing width: 15.25 mm
Modifications to high-revving engine
At the very high engine speeds, axial vibration
occurs due to the unbalance in the single-mass
damper. This can cause the crankshaft to break.
To avoid this vibration, a dual-mass damper without
unbalance is employed in the high-revving engine.
To compensate for unwanted engine vibration,
heavy metal inserts are integrated in the first and
eighth crank webs by way of unbalance.
Heavy metal inserts
Cranktrain in the RS4

11
377_057
377_058
377_062
Piston
For strength reasons forged pistons with a slightly
higher weight than conventional pistons is used.
Both engines have the same piston geometry.
– Piston weight
without rings: approx. 290 g
– Piston pin: Ø 20 mm x Ø 11.5 mm x 40 mm
Con-rod
Cracked con-rods made of 36MnVS4 are used in the
basic engine while the conventionally split con-rods
in the RS4 engine are made of 34CrNiMo8 for
strength.
In addition, the geometry of the con-rods was
reduced for the high-revving engine and the toler-
ances were reduced.
– Bearing journals: Ø 54 mm
– Bearing bushings: 1.4 mm thick,
15.25 mm wide
– Length of bushing: Ø 20 mm rolled
– Con-rod length: 154 mm
Cracking
During the cracking process, the con-rod is split at a
predetermined breaking point using a special tool.
The resultant unique breaking surface ensures the
high joining precision of the two mating parts.
Breaking surface
Predetermined
breaking point

12
377_009
Note
Modifications after start of production
In both engines, the separated oil flows
into the crankcase through the cover in the
inner vee adjacent the crankcase breather
(no longer through the chain housing).
In the Q7 engine the crankcase is vented
through a single chamber, i.e. via bank 2
only. Better antiicing protection is achieved
in this way.
After the blow-by gas has passed through the fine
oil separator, the gas flows into the intake manifold
downstream of the throttle valve.
This inlet point is integrated in the coolant circula-
tion system and heated. This prevents the crankcase
breather from freezing up.
Engine mechanicals
Crankcase ventilation
The crankcase is ventilated through both cylinder
heads.
The valve hoods incorporate a large settling space.
This space acts as a gravity-type oil separator.
A fine oil separator is connected to the valve hoods
by means of plastic hoses.
A control piston, a bypass valve, a two-stage
pressure limiting valve and an oil drain valve are
integrated in the oil separator housing.
Pressure limiting valve
Heater
Bypass valve
Fine oil separator
Crankcase breather system
Non-return valve
(crankcase breather)
Breather pipe Breather pipe

13
377_011
Function of fine oil separator
Blow-by gas volume is dependent on engine load
and RPM. The fine oil ("oil spray") is separated by
means of a cyclone separator. Cyclone separators
only have a high separation efficiency over a small
volumetric range. For this reason, one, two or three
cyclones of the fine oil separator operate in parallel
depending on the gas flow rate.
The cyclones are released by the control piston.
The displacement of the control piston against its
spring force is dependent on the gas flow rate.
Piston ring flutter at very high engine RPM and low
engine load can result in a very high gas flow rate.
The crankcase internal pressure is set by the two-
stage pressure control valve.
The bypass valve together with the control piston
ensures that the cyclones operate at the optimum
operating point (if the volumetric flow rate is too
high or too low, this will impair the functioning of
the cyclones).
When the bypass valve opens, a fraction of the
blow-by gas flows to the engine untreated, but the
remainder is optimally treated by the cyclones.
The separated oil is collected in an oil reservoir
beneath the cyclones. The oil cannot drain out of
the reservoir until the oil drain valve is opened.
The oil drain valve is closed as long as the pressure
in the crankcase, i.e. below the valves, is higher
than in the oil separator. The valve opens auto-
matically due to gravity only at very low engine RPM
or when the engine is at a standstill, because the
pressure conditions above and below the valve are
in equilibrium.
The crankcase ventilation system also includes the
crankcase breather. Air is extracted downstream of
the air filter and flows through a non-return valve
into the crankcase from above.
The non-return valve is located at the end of the
vent line and is bolted between the two cylinder
banks in the engine block.
A damping chamber is located below the non-return
valve in the engine block. This prevents non-return
valve flutter and eliminates noise.
A restrictor bore connects this chamber to the
inner chamber of the crankcase. It has the task of
supplying only a defined volume of fresh air to the
crankcase.
Control piston
Oil reservoir
Oil drain valve
Triple cyclones

14
377_012
Engine mechanicals
Chain drive
The timing gear concept is identical in all Audi vee-
engine series.
The chain drive runs on two planes.
Plane 1
Basic drive A:
drives idler gears to camshafts from crankshaft
Plane 2
Top drive B and C: drives camshafts from idler gears
Chain drive D: drives ancillary units drive module
from crankshaft
Correct chain tension is ensured by spring hydraulic
tensioners. The chain drive is maintenance-free and
designed for lifetime service.
The two engine types differ in terms of the type of
chains used and the reduction ratios in drives A, B
and C. The load on the roller chains was reduced in
the basic engine version by selecting a higher
number of teeth.
Illustration shows the Q7 engine
Q7
The camshafts in the basic engine are driven
by 3/8“ simplex roller chains.
Due to their acoustic advantages, the chains were
developed to meet the high comfort requirements.
In this case the idler gears have 40 and 24 teeth.
The camshaft sprockets have 30 teeth.
High-revving engine
3/8“ simplex sleeve-type chains are used here.
Their advantage is their reduced wear and higher
stress resistance at high engine speeds.
In this case the idler gears have 38 and 19 teeth.
The camshaft sprockets have 25 teeth.
Chain drive B Chain drive C
Chain drive D
Chain drive A

15
377_013
Ancillary units drive
The oil pump, water pump, power steering pump
and the compressor are driven by chain drive D.
The chain is driven directly by the crankshaft,
deflected by an idler gear and drives the chain
sprocket seated on the gear module.
Chain drive D
Power steering pump
Coolant pump
Gear module
Air conditioner compressor
Oil pump

16
Engine mechanicals
Cylinder head
The cylinder heads are based technically on the
well-known Audi four-valve FSI cylinder heads.
Specifications
– Aluminium cylinder head
– FSI intake ports with horizontal divisions to
produce a tumble effect
– Four-valve technology with centralised layout of
the spark plugs
– Inlet valve: chrome-plated solid stem valve
– Exhaust valve: chrome-plated sodium-filled
hollow stem valve
– Valve lift 11 mm
– Lightweight, low-friction valve gear, valve actu
tion via roller cam followers with hydraulic back-
lash compensation, single valve spring
– Two assembled camshafts per cylinder head,
driven by hydraulic swivel motors
– Intake valve opening angle 200 crank angle
degrees
– Exhaust valve opening angle 210 crank angle
degrees
– Adjustment range of the camshafts is 42 crank
angle degrees
– The adjusters are locked by locking bolts when
the engine is at a standstill; Intake in advance
position, exhaust in retard position
– Return spring in exhaust adjuster
– Implementation of "internal exhaust gas
recirculation" through the use of a correspond
ing valve overlap
Different features of the high-revving engine
To match the higher engine power output and RPM,
the following cylinder head components were
modified:
– Intake ports are charge optimised (based on
larger cross-sections)
– Intake valves are chrome-plated hollow stem
valves (for weight reduction)
– Valve springs are made of a material with higher
tensile strength and also have higher spring
force
– To meet the higher fuel requirements the
injectors are designed for higher flow rates.
– Roller cam followers are more robustly designed,
with peened rollers for higher strength
– Camshafts have different timings and larger
opening lengths
– Intake valve opening angle 230 crank angle
degrees
– Exhaust valve opening angle 220 crank angle
degrees
– The clearance compensation elements were
adopted from the VR6 engine. They have a larger
ball stroke which, in the course of testing,
proved advantageous for the high-revving
engine (with regard to the inflation of the
hydraulic valve clearance compensation
element).
– The cylinder head has a modified water jacket
which circulates coolant to the area between
the intake port and the injector and thereby
reduces the temperatures in the cylinder head
combustion chamber plate.
– Due to modified camshaft drive reduction ratio,
the camshaft adjuster has 25 teeth for chain
drive, as against 30 teeth in the basic engine.

17
377_015
377_080
High-pressure fuel pump
with fuel metering valve
Crankcase breather
Valve hood
Hall sensor
Assembled camshafts
Exhaust adjuster
with return spring
Intake adjuster

18
377_028
Oil circulation system
Design
The oil supply in the basic engine, and likewise in
the high-revving engine, is based on a classic wet
sump concept.
The focal point of development was on significant
reduction of the oil flow rate. As a result, the oil
remains in the sump for longer and is better able to
deaerate.
The oil flow rate of 50 litres per minute (at 7000 rpm
and 120 °C oil temperature) is very low for an eight-
cylinder engine. This has helped to minimise oil
pump drive power and thus improve fuel economy.
The baffle plate is designed such that it not only
prevents the crankshaft churning the oil in the
sump, but also strengthens the main bearing walls.
In the basic engine the oil is cooled by an oil-water
heat exchanger.
In the more highly stressed high-revving engine,
an additional oil-air heat exchanger is used to mini-
mise the oil temperature even at high engine load.
This additional heat exchanger is operated in
parallel with the heat exchanger via a thermostat.
Cylinder bank 1 Cylinder bank 2
Oil cooler (coolant)
Thermostat
Oil cooler (air)
Features
exclusive
to the Audi RS4
Oil pump
(gear)
Hydraulic
camshaft adjustment
Chain tensioner Oil filter module
Oil pressure
regulator

19
377_040
377_039
Oil pump
The oil pump is situated above the oil pan. The oil is drawn in through the filter in the bottom of the sump and
simultaneously through the engine return duct while driving. All engine lubrication points are swept from the
pressurised oil side.
Oil filter module
The oil filter module is designed as a full-flow filter. For easy maintenance, it is accommodated in the inner
vee of the engine. The filter element can be easily replaced without the need for special tooling. It is made of
a polymer-based nonwoven material.
Return line from the
engine
Bottom filter
on intake side
Polymer-based nonwoven
filter element
Sealing cap
from the pressure side
of the oil pump
to the engine circuit
Pressurised oil side

20
377_037
A
377_038
Oil circulation system
Sump in the Audi RS4
Especially in a sports car, a reliable supply of oil in
all driving situations is vitally important. The oil
supply system in the high-revving engine was
designed for racing applications in which it is
subjected to lateral acceleration of up to 1.4 g.
To ensure this, the sump in the RS4 has an
additional system of flaps.
Design
Four flaps whose axis of rotation is parallel to the
longitudinal axis of vehicle are arranged inside a
housing. Each of the flaps opens towards the inside
of the intake end of the oil pump.
Function
When the vehicle is cornering the oil flows inside
the sump towards the outside of the corner. The two
flaps facing the outside of the corner close and hold
the oil in the sump intake.
At the same time, the two flaps facing the inside of
the corner open to allow additional oil to flow into
the intake. This ensures a sufficient supply of oil to
the oil pump.
Direction of travel
Flap opens
(oil flows into intermediate chamber)
Flap closes
(oil back pressure is increased)
to outside of corner
acting centrifugal forces
Cutaway view A