PRODUCT INFORMATION - Alloytec V6 Engines

Maths Based Design
At the start of the Global V6 engine development program, engineers and associated technical sources created a wish list of engine attributes. This was followed by a process of prioritising those attributes against the realities of engineering, cost and manufacturing constraints.

As each system or component was specified or redefined, the engine design also changed.
This extremely complex matrix of design elements was managed in a computerised, maths-based design environment. The process reduced development times while simultaneously reducing or, in some cases, eliminating the need for physical testing, component analysis and engine simulation.

Development and Localisation
GM’s Global V6 engine family was conceived as an all-new family of modular V6 engines for global application. They were to incorporate contemporary features, packaging flexibility, multiple displacement configurations and be lightweight. At the same time they were to be cost effective and exhibit premium performance characteristics.

Holden product and manufacturing engineers have been members of a multinational GM team involved in the development of Global V6 specifications and designs since 1999. They were able to ensure that all Alloytec requirements were recognised in the initial charter.

Even with the assistance of computer-aided analysis, the unique development and localisation of the Alloytec variants took more than 200,000 hours, 143 experimental engines and 60 specific tests.

Power and Torque
The Alloytec produces 175kW of power at 6000rpm and 320Nm of torque at 2800rpm
It produces 48.6 kW of displacement. Ninety per cent of torque is available between 1630 and 5460 rpm.

The Alloytec 190 produces 190kW of power at 6500rpm and 340Nm of torque at 3200rpm.
It produces 52.7 kW of displacement. Ninety per cent of torque is available between 1570 and 5870rpm.

Continuously Variable Cam Phasing
The adoption of fully variable cam phasing – on both inlet and exhaust camshafts in the case of the Alloytec 190 and on the Alloytec inlet camshafts – provides performance flexibility, fuel economy and emissions reduction.

This electronically controlled, hydraulically actuated system enables the camshafts to rotate relative to the crankshaft, eliminating the compromises of ‘fixed’ or ‘discrete’ camshaft positions of most conventional engines.

Typically, fixed camshafts dictate valve timings that are a compromise between the desire to have the engine idle smoothly, produce good low-rpm torque, and deliver high-rpm power.

The Alloytecs’ cam phasers are continuously variable, allowing individual camshaft timing through 50 degrees of crankshaft rotation (and 50 degrees for exhaust cam adjustment in Alloytec 190).

This type of cam phasing provides greater flexibility and control of engine breathing and translates to high specific power, excellent driveability, fuel economy and low emissions without compromise.

In addition, cam phasing allows the elimination of the external exhaust gas recirculation valves.

By varying the intake valve timing, the cam phaser system improves engine smoothness at idle and optimises inlet flow dynamics for maximum performance. By closing exhaust valves later than normal, the cam phasing system forces the desired amount of exhaust gas back into the combustion chamber for more complete burning in the next combustion cycle resulting in improved fuel economy and lower emissions.

Variable Intake Manifold
A dual-stage variable intake manifold (VIM) is a feature of the Alloytec 190. The VIM incorporates an electrically operated valve within the manifold that partitions the plenum to change its volume to assist resonance tuning of the inlet flow.

When the VIM valve is shut, creating less volume, the cylinders are fed from two separate plenums. In this mode the system boosts cylinder charging in the low to mid speed range up to 4000rpm. At higher engine speeds, the VIM valve opens and all cylinders feed from a common plenum. This boosts ram cylinder charging volumetric efficiency at high speeds for increased power.

Micro-Hybrid Engine Control Unit (ECU)
The engine-mounted 32-bit Bosch Motronic ME9 ECU, a remarkably small and durable unit, is one of the most powerful and sophisticated currently available for automotive use. Its micro-hybrid design embeds all the necessary electronic circuitry on a four-layer ‘sandwich’ substrate that reduces the size of the unit and makes it stronger, allowing the ECU to be engine-mounted.

The ECU can withstand mounting temperatures of 110 degrees centigrade and vibration up to 30g. Engine mounting frees space in the under-bonnet area and eliminates attachment problems at the assembly plant.

Torque-based engine control strategy.
The engine output for the driver-determined pedal position is managed by the micro-hybrid ECU. The torque-based control strategy calculates throttle position, variable intake manifold position, continuously variable cam phasing positions and various other operational inputs and then translates that information into an ideal throttle position.

The torque-based engine control strategy is superior to earlier electronically controlled throttle-based engine-management systems that rely solely on the throttle position sensor to govern throttle opening.

Electronic Throttle Control (ETC)
An electronically controlled throttle (ETC) effectively coordinates a driver’s intentions with the actions of the various control components. ETC eliminates the traditional cable between the accelerator pedal and the throttle body. An accelerator pedal position sensor sends the driver’s command to the ECU, which then controls the throttle blade.

By eliminating the mechanical connection between the accelerator pedal and the engine, throttle opening can be controlled to ensure precise control of all other engine operating variables for improved driveability.

Ignition and Sensors
A coil-on-plug ignition system delivers maximum spark energy and precise timing, contributing to lower emissions. With fewer parts and no high-tension leads, quality, reliability and dependability are all improved.

Extended-life spark plugs with dual-platinum electrodes have an expected service life of 120,000 kilometres.

Multiple camshaft position sensors and a crankshaft position sensor are used to manage camshaft and spark timing. This dual measurement system ensures extremely accurate timing throughout the life of the engine and provides a backup in the event that one of the two sensors fails.

Returnless fuel system
Returnless fuel system architecture eliminates fuel system recirculation. This design minimises fuel heating, reducing fuel tank temperatures and consequent evaporative emissions. An integral pressure damper is used inside the fuel rail to reduce noise.

System pressure is 400 kilopascals. Fuel control, emissions, and driveability are improved by increasing the operating fuel pressure at higher engine loads to deliver the required fuel flow. In addition, the system sustains precise fuel control at lower engine loads with appropriate injector sizing.

Noise and Vibration Refinement
Key noise management techniques included:

• Increasing the stiffness of the forged steel crankshaft.
• Equal length intake manifold runners for cylinder-to-cylinder symmetry.
• Polymer coated pistons for smoother and quieter operation in the bore.
• A new oil pump designed to reduce aeration and pressure oscillations.
• Integral pressure damper in the fuel rail to reduce noise radiation.
• Structural oil pans with full circle mounting to add to powertrain bending stiffness.
• Piston oil-jets for additional lubrication of the bores and gudgeon pins.
• Two dissimilar sized holes in the PCV valve to reduce ‘hiss’.
• Composite cam-covers incorporating isolating perimeter and spark plug tube seals to decouple the covers from combustion noise; and
• Multi-layer steel damping panels inside the timing drive cover to provide additional stiffness and noise actuation.

Cylinder Block and Heads
The Global V6 engine is an aluminium-intensive basic design. The deep-skirt alloy cylinder block is cast in 319 aluminium with cast-iron cylinder liners using a precision sand casting process. The cylinder heads are semi-permanent mould 319 aluminium castings. The upper intake manifold is composed of 319 sand-cast aluminium, while the lower manifold is made of 356-T6 aluminium.

The cylinder block incorporates six-bolt main bearing caps and an oil filter mounting point.
Cast in inter-bay breather vents in the engine block reduce windage losses at high speed.

Cylinder heads utilise convergent exhaust ports for maximum flow, thermal conservation, lower emissions and reduced engine mass. Multi-layer stainless steel head gaskets are designed for durability.

Valvetrain and Timing Drive
Actuating four valves per cylinder, a low mass DOHC roller-follower valve train configuration operates with very low frictional losses to improve fuel efficiency.

Hydraulic lash adjusters and a two-stage, three-chain cam drive – rather than belts – provide improved reliability and durability. Holden has taken advantage of advanced technology to minimise the noise associated with previous generation chain-drive components.

Crankshaft, Pistons and Rods
Strength, durability and reliability were key design points for Global V6 major internal components. Weight, NVH and durability-maximising materials were specified wherever possible.

A micro-alloy 1038V forged steel crankshaft of the type most commonly found on high performance or diesel engines, is used for strength, rigidity and improved NVH characteristics.

Sinter-forged steel connecting rods offer durability, strength and low reciprocating mass. Aluminium pistons with fully floating 24-mm diameter pins and polymer-coated skirts allow tighter piston clearances for quieter cold starts.

A dual-mass flywheel with torsional damper eliminates gear rattle and driveline shudder in manual transmission applications.

The engine employs a Teflon crankshaft oil seal for lifetime leak-free performance.

Lubrication
Lubrication is critical to any engine, and the Alloytec lubrication system is designed to ensure mechanical protection and reliability combined with low maintenance.

A crankshaft driven ge-rotor oil pump was designed using specialised analysis of the pump flow to minimise oil aeration and noise. Pressure oscillations and relief valve ‘buzz’ are minimised by using tapered relief ports and a bypass baffle.

Pressure-actuated piston oil-jets help cool the underside of the pistons to achieve higher power and durability. This additional oil supply reduces noise from piston contact with the cylinder bore and from the piston wrist pin.

The structural aluminium 6.5-litre capacity oil pan employs a full-circle bolt pattern for transmission attachment, improving powertrain stiffness for reduced noise and vibration. A windage tray reduces friction losses at high speed and ensures oil supply under all operating conditions.

A top-access, cartridge style oil filter promotes easy and low cost maintenance. The replaceable cartridge element is more environmentally friendly and easier to dispose of than ‘spin-on’ designs that use leaded steel bodies.

Cooling System
A high efficiency water pump, a coolant jacket computer-optimised for volume and flow and an inlet flow location for the thermostat provide the necessary cooling for the high performance Alloytec engines. The inlet side thermostat and low volume coolant jackets promote rapid, consistent, warm up behaviour, channelling heat to the passenger compartment more quickly in winter.

Extended-life coolant requires minimal service and less frequent changes. Coolant loss protection software allows reduced-power engine operation in the unlikely event of overheating. This feature operates the engine on alternating pairs of three cylinders and allows the driver to reach a secure location.

Exhaust
New Alloytec and Alloytec 190 exhaust systems benefit from a design symmetry that improves aural quality. Computational analysis was extensively employed to gain the best possible noise quality, engine performance and durability.

Cast iron free-flow manifolds and dual close-coupled catalytic converters minimise temperature loss between engine and catalyst. This allows fast catalyst light-off times which reduce emissions.

Emissions
Alloytec meets the current Euro 2 emissions standard and has been designed for upgrades to meet proposed future standards.

Precise emissions control performance is achieved through the co-ordination of advanced engine control systems

• among them the ECU, returnless fuel system, variable intake manifold, electronically controlled throttle and cam phasing.

In addition Alloytec employs positive crankcase ventilation, evaporative emission recovery systems, wide-range oxygen sensors (Alloytec 190) and switching sensors (Alloytec).

Auto Start
Alloytec variants feature an Auto start function, where there is no need to hold the key in the 'start' position - just turn key to 'start' position and then let go.

On Alloytec manual variants the clutch must be fully depressed before starter will engage to avoid starting the engine in gear.

Servicing
Oil change intervals are 15,000km or 9 months. Spark plug changeover is at 120,000 kms.

Global V6 Design Flexibility
The Global V6 engine family encompasses a range of displacements. In addition to the 3.6L variant there are also 2.8L and 3.2L variants.

The range of potential displacements and configurations allows power and torque output suited to a variety of vehicle, platform and drive configuration requirements.

The basic Global V6 engine architecture supports a range of feature and content options, establishing a broad range of potential engine configurations. Aside from the normally aspirated/sequential port fuel injection ‘foundation’ architecture, possible major variants include:

• A spark-ignition direct-injection (SIDI) V6 of either 2.8L or 3.2L displacement.
• Fuel direct injection is a technology that can produce fuel economy gains of about 10 per cent, with no loss of performance. To be most responsive to regulatory and other market considerations, the global V6 engine design has provisions for both stratified-charge (lean-burn) and stoichiometric-charge SIDI architectures.
• Turbocharged engines of either 2.8L or 3.2L, with a variety of power and torque outputs depending on specific content. Turbocharging remains one of the best strategies to increase power and torque without increasing engine size.

The Global V6 was also developed to be easily configured to power an array of platforms, drive orientations and future-technology adaptations. Engineers anticipated many divergent uses for the Global V6 and from the start it was designed to power:

• Front-wheel drive (FWD) platforms, in which the engine is typically situated transversely.
• Rear-wheel drive (RWD) vehicles and platforms, where the engine is typically longitudinally mounted.
• All-wheel drive (AWD) architectures, which can dictate either transverse or longitudinal mounting.

The Global V6 engine is also suitable for parallel hybrid application. Parallel hybrid vehicles employ a standard petrol engine and an electric motor or motors, either or both of which can propel the vehicle. Hybrid vehicles offer the prospect of greater fuel economy and can deliver other emission and fuel-reduction possibilities.