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Department of Mechanical Engineering RCPIT, Shirpur (2011-12)
V12 Engine Page 1 of 26
CHAPTER-1
INTRODUCTION
A broad power band and smooth operation are assured as the new V-12 produces
295 horsepower and the torque output is rated at 450 Nm. The compact, high performance
engine radiates a balanced functional design. In addition to the impressive visual
appearance , the new V-12 maintains a power-to-weight ratio of 1.77 lbs/hp. From the
beginning of development, fuel economy and emission control were assigned high
priorities, resulting in a combination of V-12 performance with economical operation and
low emissions.Additional technological refinements include individual cylinder bank
management, precise electronic throttle operation and hot wire air flow sensing.
Maintenance has been reduced with the employment of self-adjusting valves and drive
belts. The engine is equipped with a powerful 2.2kW gear reduction starter motor which
provides easy starting at all temperatures. Smooth running is enhanced with the use of
small, lightweight pistons which limit the oscillating mass. Further, the strong drop-
forged crankshaft with twelve counterweights and the unitized engine/transmissionassembly reduce vibration and resonance.
It is exemplifies quiet operation resulting from the use of self-adjusting valves,
more precise internal clearances, optimized timing chain tensioning and a silent oil pump.
These noise reduction features combine with unique laminated metal/fiber/metal cylinder
head covers and oil pan which act as sound barriers.[1]
[figure-1 V12 engine]
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CHAPTER-2
CLSSIFICATION OF ENGINE
[figure-2 classification of engine]
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CHAPTER-3
COMPONENTS OF V12 ENGINE
3.1-Crankcase
The lightweight aluminum crankcase is manufactured hyper eutectically. That is
to say, special measures are employed during the formation, casting and cooling which
promote torsional resistance and dimensional stability. The crankcase is symmetrical and
can be machined to accept the starter motor on either side to accommodate market
demands of left- or right-hand drive. The cylinder banks are arranged in a 60Vconfiguration witha constant cylinder center-to-center distance of 91 mm. Cooling is
achieved with horizontal coolant flow. The cast iron main bearing caps, which are heat
treated, arefastened to the crankcase with four bolts. Two are attached parallel to the
vertical axis and two parallel to the cylinder axis. This patented configuration promotes
bottom end,
`
[Figure-3.1.1 crankcase]
stability and strength. During crankcase formation, a concentration of silicon crystals is
maintained in the cylinder bore areas. Special cylinder wall treatment and honing
produces a wear resistant silicon surface that, in combination with metal-coated pistons,
provides minimal wear and long life.[1]
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[figure-3.1.2 crankcase]
3.2-Crankshaft
The drop forged steel crankshaft has excellent torsion resistant qualities and is
supported in seven main bearings. Connecting rod journals are spaced 1200 apart with
two counterweights per journal. The axial thrust bearing is now located at the No. 7
bearing position for improved vibration damping. Similar to the design, all bearing shells
are triple layered.
[figure-3.2 crankshaft]
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3.3-Connecting rod & piston
The main bearing shells conform to the triple classification. The connecting rods
are made of drop forged steel and are similar to type. The center to center distance
is135mm, however, unlike the big end is machined asymmetrically. The special
machining allows two rods to run on one journal,
[figure-3.3 connecting rod & piston]
thus there is an "installed direction" requirement. The connecting rod bearing shells
conform to the double classification. Vibration is held to a minimum with short 60
ignition intervals and the use of low mass, light alloy pistons. The pistons have a 0.1mm
ferrous coating which provides a highly compatible operating surface for use in
aluminum/silicon cylinders. The combustion chamber bowl is located eccentrically to
concentrate the air/fuel charge central to the spark plug.
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3.4-Piston
[figure-3.4 piston]
Correct wrist pin off-set is maintained with the use of different pistons for each
cylinder bank. The top and intermediate rings are compression rings having plain and
tapered faces respectively. The oil control ring has a rubber-lined spring with a bevelled
face for good oil control.[1]
3.5-Cylinder heads
Cylinder heads are manufactured of die cast aluminum an dare identical for both
banks. Cylinder head gaskets in various thicknesses are available so that combustion
chamber volume uniformity can be maintained.
[figure-3.5 cylinder head]
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3.6-Valve arrangement
The intake and exhaust valves are arranged in a 14 V-configuration and operated
by overhead camshafts which are supported in seven bearing journals each. Camshaft
lubrication is pressure fed at the journals and with overhead oil pipes providing spray oil
to the camshaft.
[figure-3.6 valve arrangement]
This valve arrangement in conjunction with the piston bowl forms a compact
combustion chamber with excellent cylinder filling and evacuating characteristics.[3]
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3.7-Primary and secondary balance
Historically, engine designers have spoken of primary balance and secondary
balance. They are so called because they refer to vibration at the first and
second harmonic of the crank's rotational frequency, respectively. These excitations can
produce both couples and forces. Higher order harmonics also exist but, as the orders
increase, the magnitudes decrease, thus orders higher than the second are typically
neglected. The source of the higher orders is in the motion equation for a slider-crank
mechanism, which forms the basis for common reciprocating piston engines. Evaluation
of the motion equation reveals an infinite sinusoidal series, meaning there is actually no
limit to the balancing orders.
3.7.1-Primary balance
It is the balance achieved by compensating for the eccentricities of the masses in
the rotating system, including the connecting rods. At the design stage primary balance is
improved by considering and adjusting the eccentricity of each mass along the crankshaft.
In theory, any conventional engine design can be balanced perfectly for primary balance.
Once the engine is built primary balance is controlled by adding or removing mass to or
from the crankshaft, typically at each end, at the required radius and angle, which variesboth due to design and manufacturing tolerances.
3.7.2-Secondary balance
Secondary balance can include compensating (or being unable to compensate) for:
The kinetic energy of the pistons.
The non-sinusoidal motion of the pistons.
The motion of the connecting rods.
The sideways motion of balance shaft weights.
The second of these is the main consideration for secondary balance. There are
two main control mechanisms for secondary balance matching the phasing of pistons
along the crank, so that their second order contributions cancel and the use of
Lanchester balance shafts, which run at twice engine speed and so can provide a
counteracting force. No widely used engine configuration is perfectly balanced for
secondary excitation. However, by adopting particular definitions for secondary balance,
http://en.wikipedia.org/wiki/Harmonichttp://en.wikipedia.org/wiki/Balance_shafthttp://en.wikipedia.org/wiki/Balance_shafthttp://en.wikipedia.org/wiki/Balance_shafthttp://en.wikipedia.org/wiki/Balance_shafthttp://en.wikipedia.org/wiki/Harmonic8/2/2019 Report v12(Numbering)
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particular configurations can be correctly claimed to be reasonably balanced in these
restricted senses. In particular, the straight six, the flat six and the V12 configurations
offer exceptional inherent mechanical balance. Boxer eights with an appropriate
configuration can eliminate all primary and secondary balance problems, without the use
of balancing shafts. Vibrations not normally included in either primary or secondary
balance include the uneven firing patterns inherent in some configurations.
The above definitions exclude the dynamic effects due to flexure of the crankshaft
and block and ignores the loads in the bearings, which are one of the main considerations
when designing a crankshaft.[1]
3.8-Valve arrangement (for spring)
Low valve mass and dual valve springs insure reliable opening and closing
between the short ignition periods. Due to the offset of the cylinder heads,
3.8.1-Camshafts
[figure-3.8.1 camshafts]
The camshafts are of unequal length. The longer shaft is used in the left cylinder head.
http://en.wikipedia.org/wiki/Straight-6http://en.wikipedia.org/wiki/Flat-6http://en.wikipedia.org/wiki/V12_enginehttp://en.wikipedia.org/wiki/Flat_enginehttp://en.wikipedia.org/wiki/Firing_orderhttp://en.wikipedia.org/wiki/Firing_orderhttp://en.wikipedia.org/wiki/Flat_enginehttp://en.wikipedia.org/wiki/V12_enginehttp://en.wikipedia.org/wiki/Flat-6http://en.wikipedia.org/wiki/Straight-68/2/2019 Report v12(Numbering)
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3.8.2-Self-adjusting valve clearance system
[figure-3.8.2.1 self-adjusting valve clearance system]
1. Ball pin type hydraulic tappet
2. Cast rocker arm
3. Thrust guide pad
The operation of the self-adjusting valve clearance system is based on engine oil
pressure hydraulics. Clearances are taken up as oil pressure enters the hydraulic tappet
through the oil feed bore and internal one-way valve. The hydraulic pressure acts on the
adjusting piston which is displaced to reduce any non specified clearance.[2]
[figure-3.8.2.2 self-adjusting valve clearance system]
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The operation of the self-adjusting valve clearance system is based on engine oil
pressure hydraulics. Clearances are taken up as oil pressure enters the hydraulic tappet
through the oil feed bore ( arrow ) and internal one-way valve. The hydraulic pressure acts
on the adjusting piston which is displaced to reduce any non specified clearance.
1 Bleeder bore
2 Oil supply chamber
3 Oil supply bore
4 Piston
5 Body
6 Ball valve
7 Tappet pressure chamber
8 Return spring
[figure-3.8.2.3 self-adjusting valve clearance system]
Engine start-up and shut-down present thermal changes that require compensation.
The hydraulic tappet reacts to these thermally caused dimension changes by bleeding
tappet pressure back into the supply chamber when necessary.The hydraulic tappet is biased in the "clearance reduce" phase with the help of an
internal return spring. Replacement hydraulic tappets are supplied with full oil supply
chambers, therefore, proper functioning after installation is assured. Specific procedures
must be followed concerning hydraulic tappet spare parts storage, or oil leakage will
occur. Please follow instructions on tappet package.[4]
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[figure-3.8.2.4 self-adjusting valve clearance system]
3.9-Fuel injectors
The fuel injectors are mounted in the inlet flanges to produce pressurised fuel
supply.
[figure-3.9 fuel injector]
The twin camshafts are driven with a single row chain which operates in
conjunction with low noise plastic guide tubes and tensioning rails. The camshaft drive
chain lash is controlled with an automatic hydraulic tensioner.[5]
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3.10-Cylinder banks
[figure-3.10 cylinder banks]
The individual cylinder banks receive precisely balanced air charge delivery from
two symmetrical intake plenums which have equal length ram intake runners. The fuel
injectors are mounted in the inlet flanges.
3.11-Elastic sealing
[figure-3.11 Elastic sealing]
Elastic sealing plates are used to attach the plenum assemblies to the cylinder
heads. This feature acts as a sound barrier and limits vibration to the electronic throttle
valve assemblies.
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3.12-Intake plenum chamber
[figure-3.12 intake plenum chamber]
Each intake plenum chamber is equipped with a fast acting, electronic throttle
valve assembly.
3.13-flow sensors
[figure-3.13 flow sensor]
Hot wire air flow sensors are used in conjunction with Digital Motor Electronics
for measurement of physical air mass. Precise and rapid load sensing allows improved
adaptation to changing engine operating conditions. The crankcase ventilation system
vents crankcase vapors direct to the intake plenum to prevent oil mist contamination.After
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engine shutdown, the air flow sensing wire is superheated to vaporize any contaminants
which may have adhered during the previous engine operating period.
3.14-Ignition distributor and high tension cables
[figure-3.14 ignition distributor and high tension cables]
Each cylinder bank has it's own secondary ignition distributor and high tension
cables. All secondary wiring is routed and protected in a special plastic conduit developed
for this purpose.
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3.15-Oil pump
[figure-3.15 oil pump]
The oil pump is an Eaton Rotary type of tandem design. The front segment is the
primary pump which provides high pressure lubrication for all internal engine
components.
The rear segment operates as a scavenger pump insuring an adequate oil supply
for the primary pump under all operating on ditions. The scavenger pump draws oil from
the rear of the crankcase via a snorkel tube and delivers the oil to the primary pump
pickup.
3.16-Oil filter
[figure-3.16 oil filter]
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The easy access oil filter is mounted on the left inner fender. Features include
large diameter hoses to insure ample oil flow and an anti-drain back valve. Thermostatic
oil cooler control is located in the lower section. At a temperature threshold of 95C,
engine oil is directed to the external oil cooler for additional heat dissipation. Correct
hydraulic tappet operation requires engine oil which is free of all air bubbles. A special
oil deflector located in the oil pan, defoams the oil and limits splash oil precipitation.
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CHAPTER-4
SUPPLY CIRCUIT
4.1-Schematic diagram of oil circuit
[figure-4.1 Schematic diagram of oil circuit]
1. Oil pan2. Oil intake, primary oil pump
3. Primary oil pump with relief valve (4 bar, activation via filtered oil pressure)
4. Oil filter (filter cartridge bypass valve-2.2 bar, one-way check valve, oil pressure
switch, oil cooler valve-activated at 95 C)
5. Filtered oil, main gallery
6. Crankshaft main bearings
7. Connecting rod bearings
8. Piston pins (oil spray)
9. Cylinder wall surfaces (oil spray)
10. Oil feed bores in crankcase (cylinders 1 - 6 and 7 - 12)
11. Oil feed bores in cylinder heads
12. Oil gallery
13. Oil spray pipes for cam lobe lubrication
14. Camshaft bearings
15. Hydraulic tappets
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16. Timing chain lubrication (oil splash)
17. Rocker arm thrust (guide) pads (oil splash)
18. Oil supply for hydraulically-damped chain tensioner
19. Oil drain bore
20. Oil intake, snorkel
21. Oil pump, scavenger
4.2-Cooling system
[figure-4.2.1 cooling system]
Cooling system flow to the radiator is regulated with an 800 C thermostat. A ball
type valve (arrow) in the thermostat plate allows air bubble bleeding following cooling
system service.
[figure-4.2.2 cooling system]
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1. Radiator
2. Return
3. Feed
4. Thermostat
5. Water Pump
6. Right Cylinder Head
7. Left Cylinder Head
8. Connecting Pipe
9. Expansion Tank
10. Heater Core
11. Auxiliary Water Pump
4.3- V- type drive belts
[figure-4.3.1 v-type drive belts]
All accessory component rotary drive is accomplished with two poly-V type drive
belts. Once correctly installed the belts are self-adjusting with automatic hydraulic
tensioners (arrow) and thus are maintenance-free.
Component Drive Distribution:
Belt #1: Water pump, cooling fan and air conditioner compressor
Belt #2: Alternator, hydraulic fluid pump
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[figure-4.3.2 v-type drive belts]
A special lock sensor control unit monitors the A/C compressor speed in
relationship to engine RPM. In the unlikely event of A/C compressor seizure, the lock
sensor system will immediately de-energize the compressor clutch, thus insuring
uninterrupted water pump/fan operation.
The four exhaust down pipes of the exhaust assembly are mounted with springloaded ball flanges (arrows). This arrangement insures positive sealing and tends to
release any trapped stress.
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CHAPTER-5
TECHNICAL INFORMATION
5.1-Engine power and torque curves
[figure-5.1 Schematic diagram of oil circuit]
5.2-Technical data
Design - V, twelve cylinders
Displacement 4987.5 cc
Stroke 75 mm
Bore 84 mm
Power 295 hp/220 kW at engine speed 5200 rpm
Max. torque 450 Nm at engine speed 4100 rpm
Max. permissible engine speed 6000 40 rpmConstant engine speed 5900 rpm
Compression ratio 8.8 to 1
Combustion chamber volume53.3 cc
Compression pressure 10 to 12 bar
Piston running clearance 0.01 to 0.034 mm
Valve diameter
Intake valve 42 mm
Exhaust valve 35 mm
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Valve clearance self-adjusting, hydraulic
Oil pressure 4 bar
Oil volume 6.5 ltr. (+1 ltr. for oil filter and 1 ltr. for oil cooler)
Ignition Digital Motor Electronics, 30 kV system
Firing order 1-7-5-11-3-9-6-12-2-8-4-10
Distributor 2 high tension distributors
Spark plugs F8 LCR
Electrode gap 0.7 0.1 mmCO level Max. 0.7 0.5% by volume
Idle speed 700 rpm
Fuel injection- with hot wire air flow sensors[6]
5.3-Four stroke engine cycle diagram
[5.3.1-P-V Diagram]
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[5.3.2-T-S Diagram]
5.4-Advantages
Doubling the firing frequency and smoothen power delivery.
Engine speed is high. Engine torque is high. Vibration is less.
5.5-Disadvantages
High cost. Heavy in weight. Big in size there for more space is required. Average is less. Complicated in design.
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5.6- Application
This engine is use in only high speed super cars and luxurious cars like,
Aston Martin One-77
Audi Q7
Ferrari 340/342/375/375
BMW 750i/750iL/760i/760Li
Jaguar XJR15
Lamborghini 350GT
McLaren F1Mercedes-Benz CLK GT
Rolls-Royce etc...
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CHAPTER-6
CONCLUSION
Theoretically the best balanced configuration for practical use. It is simply a
duplication of inline-6 (therefore achieve the same perfect balance), with corresponding
cylinders in both banks joined at the same crank pins. V12 is better than inline-6 just
because it has more cylinders, thus doubling the firing frequency and smoothen power
delivery.