Two new SIDI (Spark Ignition Direct Injection) V6s play the leading role in the program of changes for Holden's 2010 model year upgrade of the VE Commodore. But, as a famnous knife salesman once said: "wait there's more!" Indeed, the MY10 Commodore ensemble also includes new transmissions, new tyres and a minor change to the car's IRS system.
Starting with the engines, while GM's HF (High Feature)V6 powerplant is built at Port Melbourne in 2.8, 3.0 3.2 and 3.6-litre displacements, only the 3.0 and 3.6 units are set aside for Commodore. The 3.6-litre version (codenamed LLT) powers higher-grade SV6 and Calais variants, while the new smaller (in bore and stroke) 3.0-litre V6 (LF1) will find its way into the Omega and Berlina grades.
Although the direct-injection 3.6-litre V6 has been getting around in the Cadillac CTS overseas, local development work on the engine for the Commodore application didn't begin until 2007, says Simon Cassin, Manager for Holden's Engine and Transmission Design Group.
Calibration and durability testing took place over 30 months and called for 1.1 million kilometres and 11,000 dynamometer hours.
The Carsales Network asked Cassin why the introduction of the new engines was delayed for the Commodore, when the Cadillac has been on sale with the same 3.6-litre engine for years.
"The technology's got to a price point now where it's very cost-effective -- and just delivers some great fuel economy. It's obviously more affordable in a premium product... This is the first time it's been offered at this price point in this size of vehicle, so it gives you an indication of the way things have changed over the years..."
So, how have the economies of scale improved for the new engines to become affordable?
"It's just long-term volume with these systems and it's also design improvements made over time -- not cost out, but still deliver all the advantages. A lot of it is volume-based. You'll see this technology eventually trickle down through our engine ranges and, ultimately, through other manufacturers. We're able to offer it here today in a volume -- at a very, very cost-effective and competitive price," Cassin explained.
Direct-injection fuel delivery cools the charge in the cylinder, allowing the engine to run a higher compression ratio for improved efficiency, according to Cassin. High pressure for the fuel injectors is provided by an engine-driven pump running off the exhaust cam on the left-hand bank of cylinders, allowing "multiple injection events" to suppress emissions during the cold start-up period.
"Dual-stage injection is used during cold starts and this allows us to get the catalyst up to temperature more quickly," says Cassin, "and we get a reduction in hydrocarbon emissions as a result."
Depending on engine loads, the injectors pump fuel between 2MPa and 15MPa (or between 300PSI and just over 2000PSI).
The new engines additionally come with variable cam phasing, which also reduces exhaust emissions in combination with the direct-injection system. Both engines benefit from new, "very advanced" engine control modules, which, among other things, maintain the engine's idle speed at 550rpm -- 50 rpm lower than for the outgoing Alloytec engine. They will automatically adjust the idle setting when excessive power is being drawn from the engine for the power steering system or the air conditioning.
The 3.0-litre engine features an exhaust manifold that's cast integral with the cylinder head. This reduces both mass and emissions.
"We're able to light off the catalytic converter more quickly," explains Cassin.
The upper intake manifold for the 3.0-litre is formed from a composite material, which not only saves mass, but also reduces NVH. Both these features of the smaller-displacement engine save up to 9kg of weight, in comparison with the 3.6-litre engine.
A high-efficiency alternator introduces Regulated Voltage Control (RVC) to reduce system voltage and consequently reduce the load on the alternator, thus reducing power take-off from the engine.
Most variants of the MY10 Commodore range will drive through a new six-speed 6L50 transmission, which is related to the 6L80 unit fitted to V8 variants. Built in Strasbourg, France (or Silao in Mexico from later this year), the new transmission provides a lower ratio for first gear, in order to aid launch from a standing start.
Gear changes from second through to sixth are effected in a "clutch-to-clutch manner", says Cassin, meaning that the transmission has already selected the next gear -- with clutch isolating the gear from the engine and final drive -- as the car is still accelerating/decelerating. In that regard, it's a little like a DSG transmission, but employs a conventional epicyclic configuration. GM says it allows shifts to take place very quickly and smoothly.
A turbine damper between the 258mm diameter torque converter and the input shaft for the transmission smoothes out engine output pulses for more refined operation.
"It's really aimed at allowing the engine to operate at very high efficiency and low-fuel consumption operating points," says Cassin, "so it allows us to upshift a lot earlier. Despite the reduction in capacity, we're able to upshift at very, very low speeds and relatively high loads."
Vehicles specified with the dual-fuel LPG option continue with the 3.6-litre Alloytec port-injected engine. It is matched to the old four-speed auto.
In addition to the new V6 engines and the 6L50 transmission, the MY10 Commodores are upgraded with low-rolling-resistance tyres, each of which weighs 2kg less than the previous OE tyres. Recommended tyre pressures have risen from 250kPa to 270kPa.
These tyres are complemented by a revised stability control calibration with faster onset, but without being intrusive, according to Holden.
Holden has developed a number of measures to address the Commodore's NVH. These include an 'engine bay package', a new dash and a larger-volume muffler in the free-flowing dual exhaust system.
At the rear of the car, the Commodore benefits from a re-tuned suspension system. By replacing the rubber bush in the hub carrier for the lower/rear link with a cross-axis ball joint set-up, Holden suspension engineers have reduced compliance and improved handling for cars fitted with 18 and 19-inch wheels. These cars are also equipped with a larger (24mm) anti-roll bar at the rear.
Upgraded safety for the MY10 Commodore comprises a front passenger seatbelt reminder across the range (previously fitted to Omega only) and a knee-protecting shroud under the steering column. Utes are now fitted with curtain airbags to protect the heads of the occupants. Sensors to activate the curtain airbags can react in 8 milliseconds, Holden claims.
The passenger-carrying models (sedan and Sportwagon variants) have already passed ANCAP's testing to score five stars in crash testing. Holden will submit the Ute for crash testing by ANCAP later in the year and is confident the Ute will also score five stars.
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