Next-gen tech for 3.0 Commodore

THE Holden MY10 Commodore’s upgraded 3.6-litre petrol V6 may well feature the same direct-injection technology that’s now common in many European models, but it was first employed in the Cadillac CTS and SRX more than two years ago.

In fact, while the smaller-capacity 3.0-litre direct-injection V6 was developed by General Motors for Chevrolet and Buick models, it is so far ahead of the 3.6 that Holden internally dubs it the generation-1.5 SIDI engine.

Local development of both engines began in 2007, with calibration and durability testing taking place over 30 months and involving 1.1 million kilometres and 11,000 dynamometer hours.

But it is the 3.0-litre V6, which is effectively a stroked version of the 2.8-litre V6 Holden builds for Saab, that features more advanced hardware, including a plastic-composite (rather than aluminium) intake manifold and an exhaust manifold that is integrated into the cylinder-head, saving a combined 9kg.

The 3.6L SIDI engine retains the Alloytec V6’s cast-iron external manifold, so expect similar technologies to appear on the next-generation 3.6L SIDI engine. GM Holden will also begin production of a Flex Fuel E85 ethanol-compatible SIDI V6 in late 2010.

The 3.0L SIDI engine also runs a higher 11.7:1 compression ratio (up from 10.3:1 with the superseded Alloytec 3.6), compared to 11.3:1 for the 3.6L SIDI six.

The 2.997-litre SIDI engine has bore and stroke dimensions of 89.0 x 80.3mm, giving it the same bore size as the 2.8-litre V6, while the 3.6L SIDI’s cylinders are both wider and longer, at 94.0 x 85.6mm respectively.

Thus, with 190kW/290Nm for the 3.0L SIDI and 210kW/350Nm for the 3.6L SIDI, both engines offer higher specific power and torque outputs than the 3.6-litre Alloytec V6 they replace, but the 3.0-litre engine bests both 3.6-litre engines in terms of its per-litre outputs.

Cylinder blocks and heads for both SIDI engines continue to be supplied from Hungary and Mexico, with machining taking place locally before final assembly at Holden’s $400 million Port Melbourne engine plant.

It is one of four plants to produce GM’s Global V6, which began export production for the likes of Saab, Buick, Cadillac, Chevrolet, Vauxhall, Opel and Alfa Romeo in November 2003, before the Alloytec 3.6 was fitted to Australia’s VZ Commodore and WL Statesman in August 2006.

The Holden Engine Operations V6 is produced in four displacements – 2.8-litre, 3.0-litre, 3.2-litre and 3.6-litre – for export to China, Korea, Thailand, Germany, Sweden, Mexico and South Africa.

The Spark Ignition Direct Injection (SIDI) multi-point fuel-injection system directs a cooler air/fuel mix directly into the combustion chamber and therefore permits the use of higher compression ratios and, in turn, higher performance. At the same time relative fuel consumption and CO2 emissions are reduced, as is NOx output, especially during cold starts.

The SIDI hardware comes from Bosch. Architectural development was completed by Fishermens bend engineers, in conjunction with their colleagues in Germany and North America.

A high-pressure engine-driven fuel pump delivers multiple injection events, while twin knock sensors continue to prevent ‘pinging’, especially when running on standard 91 RON unleaded.

The 3.0L SIDI’s fuel pump pressures are controlled between 2 and 15MPa, based on operating conditions, while the 3.6L SIDI’s pressures are controlled between 3.8 and 12MPa. At idle, the fuel system is regulated to about 508 psi (35 bar), increasing with demand.

The 3.0L SIDI enjoys its larger-displacement 60-degree DOHC 24-valve V6 sibling in the use of a dual exhaust system and continues to employ full four-cam phasing, fast data processing and torque-based engine management.

Those processes are managed by a new engine control module, which in this case also operates the returnless fuel-injection system, with injection and spark timing adjusted for various grades of fuel. The SIDI engines continue to feature electronic throttle control, linked to an electronic stability system, and limp-home mode.

Both SIDI V6s idle at 550rpm (50rpm lower that than 3.6-litre Alloytec) to reduce fuel consumption, with a steering wheel sensor allowing the vehicle to sense how much torque reserve is required for any given steering input and then increase idle speed as required.

A new high-efficiency alternator is smaller, lighter and more efficient, reducing generator load to aid fuel economy, while regulated voltage control allows greater use of the battery by monitoring the state of charge and allowing power to be drawn from the battery rather than the alternator under certain conditions.

Both V6s’ deceleration fuel-cut system, which sequentially cuts fuel to each cylinder when decelerating or coasting, have been optimised to minimise fuel consumption. At a certain speed and load input, fuel is seamlessly reinstated when required.

New for both SIDI engines is a turbine damper that smooths out subtle instabilities, allowing engine to operate in the most efficient low rpm/high torque range. A radial spring configuration that disconnects turbine inertia from the transmission input shaft aims to improve torsional vibration isolation between the engine and driveline.

While the cam drive and valvetrain components of both SIDI engines require no scheduled maintenance, the sparkplugs have dual-platinum electrodes and a service life of 160,000km. Accessory drive belts are scheduled for first inspection at 160,000km – the same service life for the coolant under normal use.

Meantime, the 3.0L SIDI engine’s 6L50 six-speed automatic transmission, which has a torque rating of about 500Nm instead of the 800Nm rating for the 6L80 auto fitted to V8 VE/WM models since 2006, is made in Strasbourg, France and Silao, Mexico.

Belonging to the same transmission family as the 6L80, which is also designated for longitudinal rear-wheel drive applications, the 6L50 is also found in the 2010 Cadillac CTS and CTS Wagon, Cadillac STS and Chevrolet Camaro.

The 6L50 uses clutch-to-clutch operation technology to reduce complexity and size. It control features include multiple shift patterns (full auto, sport auto, tap up/ tap down and cruise), Driver Shift Control manual override, performance mode lift-foot to either hold a gear or select a lower gear, reverse lockout, automatic grade braking and altitude and temperature compensation.