The making of a legend: HSV’s GTS

IT STARTED as a whisper almost four years ago. This week, it reaches a fully grown roar as Holden Special Vehicles unveils its most powerful passenger sedan ever – the 430kW 6.2-litre supercharged V8-engined HSV GTS.

The range-topping, 430kW GTS will have the heart of a Chevrolet Camaro ZL1 muscle car under its aluminium bonnet, a ride said to be not unlike a McLaren supercar and almost as many radiators as the fastest production car in the world, the Bugatti Veyron.

A few of the numbers are still missing, but we do know its big, unobstructed mouth – more than 30 per cent larger than for the other HSV-badged cars – will gulp in air at the same rate as the Chevy-badged Camaro.

The four rotors hidden inside the low-boost Eaton supercharger sitting between the banks of cylinders stuffs the intake manifold with 1.6 litres of air with each cycle, helping to produce a stump-pulling 570Nm of torque from low in the rev range.

Each of its front brake discs is almost as big as the alloy rims on a 1980s-era HSV-badged Commodore, while each wheel uses the same McLaren MP4-12C-inspired magnetically activated suspension set-up to almost instantaneously adjust how it rides and handles.

It also has eight separate radiators that, as well as drawing heat from the engine via a block-mounted heat exchanger, also cool the rear differential, supercharger, transmission and more.

However, it has already been a long road for the GTS, dating back to a few whispers circulating the car-maker’s Clayton workshops of a bitumen-tearing, force-fed powerplant that could also fit Holden’s Zeta platform, all taking shape at the General Motors skunkworks in the US.

According to HSV chief engineer Joel Stoddard, the LSA engine modified for the Camaro – which uses a similar engine bay to Holden’s large rear-wheel-drive platform – was little more than a rumour when the Gen-F program had its first look at a computer-generated model of the VF Commodore in December 2009.

“They took us through their overall spec of the VF Commodore – at this stage it was still a design review on a piece of paper,” Mr Stoddard said. “We got an idea of the extent of the change.” It was shortly after drawing up a list of wants and needs for the next HSV series that word of the LSA program came out.

“During that time we heard rumours and whispers, and then confirmation that LSA was going into Camaro, so we started scrambling as fast as we could to try and get that LSA into our vehicles,” Mr Stoddard said.

However, instead of the engine and transmission swapping easily between the shared rear-wheel-drive platforms, there were plenty of niggles.

“I guess the common misconception is to say that it should bolt straight in (to the Commodore’s engine bay) but nothing could be further from the truth,” Mr Stoddard said.

“We had clashes everywhere,” Mr Stoddard said. “In the tunnel, the rear module, clashing with the hood ... it was so close yet so far.” The list of annoyances is detailed. The engine, for instance, had to sit lower so the Commodore-sourced aluminium bonnet could still close. It also had to sit on a slight rearward angle so the transmission – which sits comfortably inside the Camaro’s belly – would fit inside the tunnel behind the firewall.

Then there were the fiddly bits. The most difficult for Mr Stoddard’s team was fitting the manual gearbox’s shifter inside the HSV donor car’s skin.

“The shifter was sitting about 30 centimetres too far back in the housing, so we had to re-engineer the shifter mechanism to move it forward by 40cm,” he said.

“Before we did that we were having real problems trying to select fourth and sixth (gears).” The GTS also has to sit on relatively high-profile tyres. This is because the canted engine and bigger differential hang so low the performance hero needed extra ground clearance, and the easiest way to do this was to increase the tyres’ side profile.

Incidentally, the also-wider rear tyres meant that HSV had to add a small flap at the rear of the wheelarch to meet regulations that spell out how much tread can protrude past the guard. The GTS needs it to stay road-legal.

Because of these niggles, HSV missed the August 2010 deadline to have the LSA approved by the start of Holden’s production cycle for the VF Commodore. It had also missed its cut-off date for GM’s development cycle for the supercharged V8 engine.

“We got it (the LSA engine development) all approved by December 2010 ... but that meant we were three months behind the main program, and that’s because of the system we use in GM – we have a program where you can’t make months up because there’s set goals and milestones that you have to meet,” Mr Stoddard said.

“We’re working to that template, so that’s why LSA is a bit late.” Late it is, launching here in August for a pricetag believed to sit below $95,000 – suggesting the big performance numbers will also attract a big premium in the showroom.