Lamborghini Diablo Engine. Manual

Workshop manual - Diablo 6.0

10-3

DESCRIPTION

Otto cycle – 4 intake stroke engine, 12 V cylinders at 60°; timing system with 4 valves for each cylinder, double overhead camshaft
controlled by double chain, phase variator on intake, indirect MPI injection (one injector for each cylinder), static electronic ignition
(one coil per cylinder), liquid cooling with double radiator, forced lubrication with oil radiator, exhaust six in two in one with catalyst.
Aluminium alloy and H+T silicon “open deck” type crankcase with wet inserted liners.
Steel alloy liners with Nikasil treated internal surfaces. This treatment ensures a very high surface hardness.

Cr Mo hardened and tempered steel crankshaft, the working surfaces are hardened by gaseous nitriding. The crankshaft bearings
are smooth. The main bearing caps are integrated in a block structure to give maximum stiffness.

Titanium alloy connecting rods with modular head, smooth bearings at big and small ends.
The pistons are in pressed light alloy with three rings, two seals and one oil scraper.
The cylinder heads are aluminium alloy and H+T silicon, with bronze valve guides and cast iron valve seats.
The timing system consists of two overhead camshafts for each cylinder bank, controlled by double chains with phase variator on
the intake shafts.
Motion is transmitted directly from the crankshaft to two gear wheels by means of a double chain. Each of these gear wheels in its
turn controls the two camshafts of each head by means of double chains.
The chain tension is ensured by hydraulic chain tighteners that operate with the lubrication circuit oil.
The cooling system with two cooling radiators is a closed loop system with forced circulation by a centrifugal pump belt driven by
the crankshaft.
The lubrication is forced by a gear pump with a vented gas recycling system and radiator to cool the oil.

This type of liner cannot be lapped.

Each time the crankshaft is undersized, it is most important to restore the surface hardness by the special heat treat-
ment.

Index

Workshop manual - Diablo 6.0

10-5

Cylinder numbering and direction of crankshaft rotation
The engine rotation is anticlockwise (as seen from the timing side).
The engine cylinder banks are defined as right and left hand as seen from the flywheel.
The No. 1 cylinder is the first of the left hand cylinder bank near the flywheel, the numbering continues following a U towards the
right hand cylinder bank.

Fig. 2 – Numbering of cylinders

181002

Engine flywheel side

Timing side

Direction of rotation
(counterclockwise from timing side)

Travel direction

SX = Left hand cylinder bank (cylinder bank 1-6)
DX = Right hand cylinder bank (cylinder bank 7-12)

Index

Workshop manual - Diablo 6.0

10-6

SPECIFICATIONS AND DATA

Crankshaft

The 1st undersizing is no longer available.

Crankshaft end float

0.155 to 0.315

Crankpin and conrod journals surface hardness

HV1 630

Crankpin and conrod journals surface finish

0.2 mm

Crankpins:
Rated diameter D
2nd undersizing

62.966 to 62.979

62.712 to 62.722

Conrod journals:
Rated diameter d
2nd undersizing

45.482 to 45.500

45.236 to 45.246

Shoulders:
Rated width
Oversized thickness

40.070 to 40.100

40.578 to 40.608

Whenever crankshaft undersizing is performed, it is most important to restore the surface hardness with special treat-
ment of the NITREG type, attaining to these specifications:
temperature:

530 °C

times:

rising 4 hours
holding 40 hours
descent 4 hours

depth of nitriding :

0.35 to 0.40 mm

hardness:

HV1: 600 to 680
HV10: 550 to 630

white sheet thickness:

< 10 microns

Index

Workshop manual - Diablo 6.0

10-7

Fig. 3 – Crankshaft

Connecting radius R

(*) apply a force P=5200 N as indicated in the figure.

Crankpins

2.0 to 2.2

Conrod journals

2.0 to 2.2

Protrusion from crankcase edge (bushing) s

0.125 to 0.150 (*)

Bushing/shaft clearance

0.010 to 0.050

031003

Index

Workshop manual - Diablo 6.0

10-8

Crankcase

Fig. 6 – Crankcase

Fig. 4 – Crankshaft

Fig. 5 – Crankshaft bearings

Crankpin seat diameter d

66.675 to 66.688

Liner seat diameter D

92.000 to 92.035

031004

031005

031006

Index

Workshop manual - Diablo 6.0

10-9

Conrods

Fig. 7 – Conrods

Piston pin seat Ø (small end) d

20.020 to 20.030

Conrod bushing seat diameter (big end) D

48.626 to 48.642

Axis parallelism tolerance (piston pin-shaft)

C – C1=

0.03

Conrod big end width

19.900 to 19.905

Conrod small end width

20.750 to 20.755

Distance between centres i

135.97 to 136.03

Piston pin and conrod small end bushing assembly clearance

0.020 to 0.080

Interference between piston pin bushing and conrod hole

0.050 to 0.096

Conrod journal bearings on crankshaft assembly clearance

0.024 to 0.067

031007

Index

Workshop manual - Diablo 6.0

10-10

Piston liners

(*)

measure with a liner-stop pre-load P=30 [N]

The big end grooves are to face the crank arms when fitting the conrod-piston group.

If one or more conrods are replaced, it is essential that the spare parts are identical to the originals. (PANKL or LAM-
BORGHINI).

Rated diameter

Group A

86.995 to 86.985

87.005 to 86.995

87.015 to 87.005

Height ha

Diameter a

Group A

86.995 to 86.975

87.005 to 86.985

87.015 to 86.995

Height hb

Diameter b

Group A

89.995 to 86.985

87.005 to 86.995

87.015 to 87.005

Height hc

110

Diameter c

Group A

87.005 to 86.985

87.015 to 86.995

87.025 to 87.005

Liner protrusion from crankcase edge s

0.4 to 0.7 (*)

Maximum taper

0.02

Maximum ovalisation

0.03

Surface roughness

0.3 micron

Index

Workshop manual - Diablo 6.0

10-12

Pistons

Rated diameter

Group A

86.900

0.009

86.910

0.009

86.920

0.009

Total height H

47.1

Piston crown-piston pin axis
height H1

29.050 to 29.150

Piston pin axis-lower edge
height H2

17.8 to 18.0

Step I – slot h height

6.1 to 6.3

Height I slot a

1.230 to 1.250

Height II slot b

1.770 to 1.790

Height III slot c

3.010 to

3.030

Pistons must always be coupled with liners belonging to the same group. Pistons and liners belonging to the same
engine must all be of the same group.

Index

Workshop manual - Diablo 6.0

10-13

Fig. 9 – Pistons

Piston pin

Diameter

19.995 to 20.000

Seat diameter

20.010 to 20.016

Piston pin-piston clearance

0.010 to 0.020

031009

Index

Workshop manual - Diablo 6.0

10-14

Piston rings

(*) measured with piston ring fitted in the liner.

SLOT I

Height s

190 to 1.175

Thickness b

3.70 to 3.45

Gap between ends l

0.20 to 0.40 (*)

Slot-piston ring clearance

0.040 to 0.075

SLOT II

Height s

1.740 to 1.728

Thickness b

3.70 to 3.45

Gap between ends l

0.30 to 0.50 (*)

Slot-piston ring clearance

0.020 to 0.062

Diameter b

SLOT III

Height s

2.990 to 2.975

Thickness b

3.00 to 2.75

Gap between ends l

0.25 to 0.50 (*)

Slot-piston ring clearance

0.020 to 0.055

Index

Workshop manual - Diablo 6.0

10-16

Cylinder heads

Fig. 11 – Cylinder head

Tappet housing diameter (a)

33.015 to 33.030

Intake valve seat housing diameter (b)

30.560 to 30.580

Exhaust valve seat housing diameter (c)

30.560 to 30.580

Valve guide housing diameter (intake and exhaust) (d)

12.00 to 12.018

0310011

Index

Workshop manual - Diablo 6.0

10-17

Valves

Valve seats

Intake

Stem diameter d

6.950 to 6.970

Reduced stem diameter d1

6.50 to 6.60

Valve head diameter D

33.3 to 33.5

Valve seat angle °

45°

5’

Height h

103.69 to 103.84

Tappets support thickness s

3.45

Exhaust

Stem diameter d

6.950 to 6.970

Valve head diameter D

29.3 to 29.5

Valve seat angle °

45 °

5’

Height h

103.59 to 103.74

Tappets support thickness s

3.35

Intake

Rated inner diameter

0.10

Rated outer diameter

34.7

0.01

Contact fascia angle

45°

Exhaust

Rated inner diameter

0.10

Rated outer diameter

32.7

0.01

Contact fascia angle

45°

Index

Lamborghini Diablo Engine. Manual - part 1