Cadillac to get first HFV6 engine

While the new VY Commodore is still sitting pretty at the top of the large car sales chart in Australia, Ford has managed to eat away at Holden's lead in the last few months.

While the new Falcon brings with it a plethora of new features, perhaps the biggest advantage it holds over the Commodore is a 30kW power advantage.

The new Ford-built DOHC straight six-cylinder mill is quite a piece of work, and Holden is well aware of this.

In October this year (2003), Holden will have finished integrating new technology needed to build the new HFV6 at its Fisherman's Bend, Port Melbourne facility.

The 'High Feature' V6 will be offered in four sizes, from 2.8 to 3.8-litres, and while the Aussie-spec VE Commodore, due in 2005, will pack the 3.8-litre engine, there are rumours that GM may export a sub 3.0-litre VE Commodore to Euro markets in 2006.

The all-aluminium engine construction will feature dual overhead camshafts, 4-valves per cylinder and continuously variable cam phasing, though rumours suggest that the Commodore will get a fairly basic model without variable cam and valve timing.

The Fisherman's Bend production line is one of only two facilities in the world to manufacture GM's new HFV6 engine - the other plant at St Catherine, Canada - and the new powerplants will be exported worldwide from 2004, with the first vehicle to make use of the HFV6 a Cadillac.

The new Cadillac CTS will be launched in the US in 2004, and will ship with a 3.6-litre V6 with variable valve timing.

The rear-wheel drive CTS is the American equivalent of a BMW 5-series or Audi A6, and the new powerplant is eagerly awaited by many.

General Motors knew it was lagging behind in the mid-to-large engine department, so the HFV6 was designed to incorporate all the latest developments to improve refinement, efficiency, and our favourite - power.

To start with, the new Caddy's 3.6-litre mill makes use of fully variable valve timing for both intake and exhaust valves, and the quad-cam design (DOHC per cylinder bank) ensures VVT aspect is utilised to the full.

The result of this means that some 90 per cent of the 3.6-litre engine's torque is available from as low as 1600rpm, all the way to 5800rpm.

"Flexibility was very important," said Bob Jacques, base engine design system engineer for GM. "We insisted on going after high performance and high refinement at the same time.

"We went after all the benchmarks. You name it - if there is a good V6 out there, we found out how and why it was good."

The result is an impressive amount of torque and power, but also a supremely wide power band spanning some 3000rpm.

190kW of power hits @ 6200rpm, while 342Nm of torque peaks @ 3200rpm.

Quite impressive for the 3.6-litre mill, we can't wait to see what the 3.8 churns out.

Compared to an existing General Motors DOHC V6, the 3.6-litre V6 VVT develops 20 per cent more peak power and a 13 per cent increase in peak torque.

While the base-model VE Commodore Executive isn't likely to benefit from a top-range V6 (fully loaded with variable valve timing and cam phasing) you can be sure that the current pushrod 3.8-litre six will be comfortably eclispsed in both power and torque.

Berlina, Calais and perhaps even Statesman variants are more likely to benefit from a 3.8-litre HFV6 will all the trimmings.

What are all the trimmings? Electronic throttle control, or drive-by-wire, a more powerful 32-bit fuel-injection processor, a forged-steel crankshaft, piston-cooling oil jets and coil-on-plug ignition.

The General's new engine employs isolated cam covers, to reduce vibration, while the engine front cover incorporates internal damping plates to also quell engine vibrations. A structural aluminum oil pan, attached by a full-circle mounting, enhances bending stiffness and mitigates "drumming" from the oil pan, all of which help reduce NVH levels.

Internally, polymer-coated piston skirts help the piston to track more smoothly and quietly in the bore and pressure-actuated piston-oil squirters help cool the pistons, contributing to performance and durability. Again, this also helps reduce NVH levels.

The camshaft sprocket employs durable, molded-rubber "cushion rings" that absorb the noise of the camshaft drive engaging the sprocket teeth.

A forged steel crankshaft ensures the durability required of high specific output variants and provides an extra degree of robustness.

Three pressure-actuated piston-cooling oil-jet assemblies in the block each hold a pair of oil squirters that douse the underside of the piston and the surrounding cylinder wall with oil.

This practice reduces piston temperatures, which helps the engine develop more power. The cooler piston/cylinder interface also enhances long-term durability.

Flexible oil pan configurations facilitate the engine's adaptability for all drive layouts: V6 VVT engines destined for AWD applications, for instance, are fitted with an oil pan cast specifically with a pass-through so that the front-wheel half shaft can be fitted.

There has been some speculation that the new high feature six-cylinder mills may even benefit from forced induction, though the chances of Holden releasing a turbocharged S or SS Commodore to rival Ford's XR6 Turbo are slim.

A twin turbocharged six wouldn't be out of the question for GM vehicles in other markets, such as Vauxhall in the UK, Saab in Sweden, Alfa Romeo in Italy and Opel in Germany.

It will be interesting to see how quickly the new Cadillac CTS sprints from zero to one hundred - one would expect a time of below 8.0 seconds - but because we don't the weight of the '04 Caddy, it's quite hard to say.

Still, at the very least we are starting to see how GM's new HFV6 works, and if the 3.6-litre mill is any indication, the 3.8-litre variant due for the next Commodore should give Ford's 4.0-litre six something to think about.