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The Engineering Behind the 2001 Monaro

The inside story from the people who designed it.

By Andrew Hynson, Manager Special Vehicles, Holden Ltd

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The Monaro program presented an opportunity to test Holden's mettle in terms of its capacity to design, engineer and manufacture a car in a very tight time frame. "Business as usual" would simply not deliver a car in the time available.

The Holden Monaro project represents a total investment of $60 million, consisting of $40 million for plant and tooling and $20 million for design and engineering. The design and engineering investment was halved by using the latest Computer Aided Engineering techniques.

Non-Traditional Development

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Traditionally, when we're developing a car, we build physical prototypes to test both crash and durability performance, before committing millions of dollars to production tooling. But on the Monaro program we did all of the vehicle crash and durability development virtually. That is, all on computer.

When we knew we had the design right, we went straight to production tooling. The final validation was completed using pre-production vehicles at our proving ground and on Australian roads.

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The total time taken from styling freeze to start of production was just 22 months. In order to achieve such a rapid acceleration in the way we engineer a vehicle, we decided to run the operation as a 'skunk works'. In October 1999 we pulled together a dedicated team of 12 engineers and set up a separate engineering office. We also assembled a team of approximately 20 CAD designers. Our mission was clear: develop a 21st century Monaro using some of the most sophisticated computer aided development tools in the world.

And do it radically faster than we have ever done a program before.

What followed for the Monaro engineering team was the busiest and most exciting two years of our careers. The challenges were considerable. For much of the program, we had no history to guide us. Fortunately there's a fantastic depth and breadth of experience within Holden, so we were able to tap into expert knowledge across a broad range of science and engineering disciplines, including a dedicated team of three manufacturing engineers at our plant in Elizabeth (South Australia).

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The Monaro was fully designed and validated virtually using Simultaneous Math Based Processes (SMBP). It is the first Holden in history to have been designed virtually, without the usual prototype phases and physical development.

The Monaro was fully developed using GM's UniGraphics package. All new components were designed as solid models, not surfaces, which were used previously. This represents the continuing march of design towards parameterised math models.

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We were so confident in our virtual designs that we commenced cutting the major long lead tools before we had completed all the design and analysis!

The acid test came last January when we commenced building the first car. On February 26 this year, the first real Monaro was finished. We were so encouraged by the results that we ended up building all the remaining Monaros straight down the production line amidst our normal assembly operations. This is a first for a program of this magnitude.

Body Structure

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In line with Holden's single platform strategy, the Monaro program utilised the Commodore architecture, sharing all sheet metal forward of the A pillar. Rearward of the A pillar there are 84 major new body components.

The new component breakdown is as follows:

  • Bodyside - 29 panels
  • Underbody - 23 panels
  • Doors and Decklid - 32 panels
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Major changes are as follows:

  • the windscreen is raked back an additional two degrees
  • the B pillar is relocated 150mm rearward to enable access to the rear seats
  • the doors are 150mm longer
  • the roof is 40mm lower
  • the seat mounts are lowered by 25mm
  • the rear overhang is reduced by 100mm.

The aerodynamic drag coefficient (Cd) for the Monaro is 0.31.

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From a structural point of view, the doors presented an interesting challenge. The increased length and mass of the Monaro doors required substantial changes to match the four-door model's strength and stiffness. We designed a number of improvements using computer simulation. The hinge side reinforcement was changed to high-strength steel, the hinge flaps were extended to double the mounting area on the body, and a gusset was added to increase torsional stiffness. The result is a door with 24 per cent reduced vertical deflection.

An intensive body structure analysis program included crashworthiness, durability, aerodynamics and noise and vibration development. Monaro's body bending stiffness is increased by 23 per cent over the VX Commodore sedan and torsional stiffness is increased by five per cent.

Safety Features

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The Monaro has a comprehensive occupant safety system. This includes:

  • Driver and passenger airbags
  • Driver and front passenger side impact airbags
  • Pyrotechnic seat belt pre-tensioners on the front seats
  • Anti-submarining ramps
  • Revised rear seat belt system
  • Revised child restraint anchor points, located behind the rear head restraints
  • Adjustable head restraints in all seating positions
  • New centre-mounted stop lamp

The safety performance of the Monaro and its efficient crash energy management characteristics were achieved using the latest computer simulation processes. The sensing system has been re-calibrated to ensure that the new body structure provides the same level of protection as VX. The side structure has been extensively developed to control the deformation profile in a crash to reduce the intrusion velocity and therefore the injury risk.

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The rear structure has been developed to maintain controlled crush characteristics in rear impact collisions. Ultra high-strength steel reinforcements have been added to direct and absorb impact forces in a rear collision.

The new centre high-mounted stop lamp is an LED design for improved rear visibility, low energy and faster response time. The faster response time provides the additional safety benefit of alerting other drivers 0.2 of a second faster than a conventional lamp. This improves stopping distance by 4.7 metres at 100 km/h.

Seating

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The Monaro offers genuine four-seater accommodation, with the following features:

  • 8 way power seats
  • 3 position memory on the CV8 driver's seat
  • Automated fold forward system for both front seats for access to the rear seats. Both front seats return automatically to their original position.
  • Faster fore/aft motors on both seats to improve rear seat access
  • Bolster wires in all cushions for improved lateral support
  • Microprocessor control for both front seats with occupant sensing mat.

The Monaro seats feature unique comfort contours and pads using dual hardness foam. They have been tuned specifically to match the car's suspension for optimum ride comfort.

A sophisticated microprocessor-controlled fold-forward system has been developed which enables effortless access to the rear seat. The system is controlled by a seat-mounted microprocessor which powers the seat to full forward when the lever on the top of the seat back is activated and the back is de-latched. The seat will then return to the original position when the seat back is re-latched.

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The automated fold forward system also features an electronic occupant sensing mat which controls the activation of the system. The sensing mat ensures that the seat will not move forward if the lever is activated and the front seat is occupied, eliminating the potential for occupant crush. All automated seat movement can be cancelled by operating any of the side-mounted seat switches.

The full size Monaro rear seats have been specially designed for two occupants and feature unique contours that achieve similar comfort levels to the front seats.

The rear seat packaging has been developed to enable adults to ride in the rear with a comfortable amount of headroom and legroom, making the Monaro a true four-seater vehicle.

Powertrain

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There are three powertrain combinations available on the Monaro. The CV6 model uses the 3.8 litre Supercharged V6 with 4-speed electronic control automatic, while the CV8 comes standard with Holden's 5.7 litre Gen III V8 and a choice of 4-speed electronic control automatic transmission or 6-speed manual transmission. Wide open throttle power and torque for both engines remain unchanged.

The CV6 achieves 7.6 l/100km highway cycle and 12.5 l/100km city cycle. The CV8 manual returns 7.4 l/100km highway and 13.0 l/100km city. The CV8 automatic returns 8.0 l/100km highway and 13.0 l/100km city.

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As part of creating a unique character for the Monaro, we looked very closely not just at how the car looked and handled, but also how it sounded.

The V8 Monaro induction system has been re-designed to provide enhanced vehicle response and noise character during moderate to heavy throttle applications. The result is a subtle yet purposeful noise character that lets the driver know what the engine is doing.

Changes to the system from the current VXII V8 include:

  • A new cold air intake shroud designed to isolate the intake air from the engine bay to improve hot idle drive away.
  • The inlet air temperature sensor has been relocated to the throttle body duct, improving system response time to changes in the inlet air temperature. This improved response time enables enhanced spark timing and subsequent performance improvement.
  • The air cleaner assembly has been revised to suit the new shroud and the relocated inlet air temperature sensor.
  • A unique tuning tube was added to give the desired noise character.

Lighting

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The Monaro has distinctive front and rear lamps. The front lamps include new generation quartz halogen H9 and H11 bulbs with more precise tolerances that improve lamp performance. High-Multi Focal Reflector (MFR) technology is used to complement the new generation of bulbs. The low beam lights use projector technology which throws a wide and even beam pattern. Safety is improved by reducing the glare to oncoming vehicles, especially in the wet.

The high beam uses the highest output bulbs to maintain high beam performance from a single bulb system.

Vehicle Dynamics

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Even before we started developing the math models of the car, we knew precisely how we wanted it to feel from the driver's seat. Our goal was to create a vehicle that had a unique dynamic character by developing the chassis system to give the best possible handling without significantly compromising ride comfort. Sports luxury was what we wanted to achieve.

Suspension and steering systems have been comprehensively revised. Our development program resulted in:

  • Revised front springs and re-designed rear springs
  • Increased front and rear stabiliser bar diameters
  • Completely retuned front struts and rear dampers
  • New steering gear
  • Control link IRS
  • New 18-inch wheels and tyres for the CV8.

For the CV8 model, we chose 18-inch wheels combined with wide, low profile tyres to give the Monaro precise steering response and predictability combined with maximum cornering tractability. In order to achieve the balance between precision and comfort, we worked with our Bridgestone counterparts to modify the internal construction of the tyre. The result is a tyre that gives exceptional grip and precision, combined with good comfort characteristics.

For the CV6 we chose to use the 17-inch VX SS sedan wheel and tyre combination.

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Straight-line directional stability was improved by balancing the stiffness of the steering gear valve torsion bar with that of the lower control arm bush, so that lateral forces on the front wheels due to crosswinds and road camber produce minimal deviations from the desired course.

Steering precision was refined by slowing the steering gear ratio by 13 per cent and increasing torsion bar stiffness in the steering gear valve by 14 per cent. The new steering gear (three turns lock to lock) facilitates lighter parking effort.

Steering response - the phase delay between an input from the driver and the reaction of the vehicle to the input was sharpened by the addition of a new control valve in the steering gear and by significant modifications made to the internal construction of the CV8's 18-inch 235/40 R18 Bridgestone tyre. The 17-inch 235/45 R17 93V tyre specified for the CV6 also exhibits good response characteristics.

Cornering linearity was enhanced by revisions to spring rates and stabiliser bar balance in conjunction with new shock absorber and strut valving.

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Predictability - the ability of the chassis system to provide continuous driver feedback was enhanced through a combination of changes to the steering, tyres and shock absorber and strut valving.

Cornering tractability was optimised through a combination of roll control, shock absorber and strut valving and tyre construction. The chassis set-up is also designed to be balanced through corners under power. Consequently, if a mid-corner deviation is necessary, throttle lift-off will immediately provide additional traction to the rear wheels and the associated weight transfer to the front wheels will provide additional traction and the vehicle will remain dynamically stable.

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Ride comfort - Steps taken to isolate road surface irregularities while maintaining good motion control included opening the primary valving (bleeds) of the shock absorbers and struts and tightening up high speed valving. Ride quality is enhanced by internal tyre construction, particularly that of the 18-inch tyre developed specifically for the Monaro, and improvements in seat damping characteristics.

Monaro Specifications

  SUPERCHARGED V6 GENERATION III V8
ENGINE 'V' configuration.
Cold air intake. High flow air cleaner.
OHV design with cross flow cylinder heads.
Sequential fuel injection.
High energy, distributorless, ignition.
Twin knock control sensors.
Computer diagnostics.
Electric cooling fan.
Low restriction dual exhaust in stainless steel.
Cross-bolted main bearings.
  4-bolt 6-bolt
  Electronic control supercharger. Aluminium alloy block & cylinder heads.
  Triple coils. Coil-per-cylinder.
BORE x STROKE (mm) 97 x 86 99 x 92
CAPACITY (cc) 3791 5665
COMPRESSION RATIO (:1) 8.5 10.1
RECOMMENDED FUEL OCTANE RATING 95 (PULP)
Alternative: 91 (ULP)
91 (ULP)
POWER (DIN, kW) 171 @ 5200rpm (PULP) 225 @ 5200rpm
TORQUE (DIN, Nm) 375 @ 3000rpm (PULP) 460 @ 4400rpm
GEAR RATIOS (:1) Auto Manual Auto
1st 3.06 2.66 3.06
2nd 1.63 1.78 1.63
3rd 1.00 1.30 1.00
4th 0.70 1.00 0.70
5th   0.74  
6th   0.50  
Final drive ratio 3.08 3.46 3.08
FUEL ECONOMY (L/100km*)[mpg] Auto Manual Auto
City 12.5
[22.6]
(PULP)
13.0
[21.7]
13.0
[21.7]
Highway 7.6
[37.1]
(PULP)
7.4
[38.1]
8.0
[35.3]
PETROL TANK (L) 75
BRAKES Four wheel disc.
Ventilated front disc & finned caliper.
ANTI-LOCK BRAKING SYSTEM (ABS) 4-channel.
TRACTION CONTROL (TC) When sensors detect imminent rear wheel spin, engine torque is reduced. If one wheel is about to spin, braking is applied to transfer torque to wheel with better traction.
SUSPENSION - Front MacPherson strut. Direct acting stabiliser bar. Progressive rate coil springs.
Rear Control-Link Independent Rear Suspension (IRS). Semi-trailing arm. Progressive rate miniblock coil springs. Stabiliser bar.
COUPE FE2 SPORTS SUSPENSION - Front Sports springs. Revised stabiliser bar diameter. Reduced ride height.
Rear Sports springs. Gas pressure dampers.
STEERING Variable ratio rack & pinion.
TRACK (mm) Front: 1559 Rear: 1577
TURN CIRCLE (kerb to kerb, m) 11.0
WHEELBASE (mm) 2788
EXTERIOR DIMENSIONS(mm) Length Width Height
  4789 1841 1397
INTERIOR DIMENSIONS(mm) Leg Shoulder Head Hip
Front 1072 1515 946 1472
Rear 942 1312 848 1275
CARGO (L) 370
KERB WEIGHT (Est. kg) Auto Manual Auto
  1603 1640 1645
TOWING Holden approved 1600kg towing equipment is available.
See your Holden Dealer for details.
SERVICE 1500km (free) inspection, 10,000km then every 10,000km.
Maintenance-free, long life, accessory drive belt with automatic tensioner. Dual belt on V8.
Holden Dealer 'Tech 2' computerised analysis available for engine management system.

* Fuel consumption figures based on AS2877 tests.

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