The HSV GTS Coupe is king of the LS1-powered monsters in Australia. Its sexy
profile combines with Calloway C4B grunt (all 300kW of it!) to create a package
that has car enthusiasts tripping over their tongues.
You just want one?
Sure. Come and join us near the back of the queue!
One of the first people on that queue for a new GTS Coupe was Doug X of
Queensland. Since first laying eyes on the mighty Coupe, Doug had been preparing
mental notes on what he thought could be done to ‘take it to the next
After discussions with John Whittaker of Brisbane Tuning and Turbo Centre, a
full-scale attack was launched on the new HSV. John says everything was done in
one big hit – there were no dribs and drabs modification here!
Not wanting to pull apart the Calloway engine, Doug decided bolt-on products
were the way to go. A big ‘800hp’ version of the latest Vortech supercharger is
bolted to the front of the block using parts supplied in an off-the-shelf CAPA
kit. Brisbane Tuning and Turbo has modified the CAPA kit to incorporate a
Gilmer belt drive system and an in-house developed water injection system with a
high-pressure electric pump.
With the big Vortech whirring to the tune of 12 psi and a relatively high
9.8:1 static compression ratio, an effective intercooler is essential. The CAPA
air-to-air intercooler kit is installed with custom mandrel bent and polished
plumbing. Heat exchange is further helped along with fitment of a nitrous spray
bar. The spray is triggered by the programmable management system and a manual
switch which opens the bottle. The large nitrous bottle can be found in the
With 5.7 litres of boosted C4B, you’re talking a lot of gas flow. Brisbane Tuning and
Turbo has fabricated a set of big-bore headers leading into a twin 3 inch
mandrel system with high-flow cats and mufflers. Nice. Very nice!
On the intake side, a K&N pod filter inside the front left guard
protects the compressor, there are twin Bosch Motorsport blow-off valves and a
78mm HSV throttle body feeds the stock intake manifold.
Not afraid to spend bux where it’s needed, Doug ripped out the factory engine
management system and whacked in a top-line MoTeC M800 programmable unit. This
controls a set of huge 1000cc injectors working with modified rails, bigger
lines, a surge tank and a ‘1000hp’ pump fed by a low-pressure lift pump. Not
much is left of the standard fuel system.
All of this is hung on the back of a bog-stock C4B engine. The C4B engine
already boasts CNC-ported heads, an aggressive cam and upgraded valvetrain – a
major advantage over lesser model LS1s.
Brisbane Tuning and Turbo carefully programmed the M800 management system to
provide as much power as possible while still allowing detonation-free use of 98
RON pump fuel. The fuel and ignition maps were tickled until the in-house Dyno
Dynamics chassis dyno showed a sizeable 423kW at the treads. Peak power is
reached at around 6100 rpm and there’s good, useable torque through the rev
range. An aftermarket oil cooler and power steering cooler have been added to
ensure temps stay out of the red.
The stock Holden/HSV driveline is strong bugger and there hasn’t been any
need to upgrade the stock T56 ‘box. The clutch is a custom Brisbane Tuning and
Turbo part and the stock Hydratrak diff has been exchanged for a KAAZ mechanical
type unit with a 3.9:1 ratio (the same as standard). A modified tailshaft and
new rear axles are also installed.
Rather than mix ‘n’ match suspension components, Doug’s GTS Coupe runs
coil-overs, swaybars and bushes the same as used in Peter Brock’s Targa race
car. Brisbane Tuning and Turbo can be thanked for sourcing the parts and
installation. The Targa suspension set-up provides a liveable ride together with
excellent balance – as you’d expect.
Brake-wise, huge six-pot HSV front calipers team with DBA slotted and drilled
replacement discs and competition pads to ensure powerful braking. The rears are
standard HSV four-potters with less aggressive aftermarket pads.
But forget about the lowered stance and muscular looking brakes – this
machine never fails to grab attention with its yellow paint, abundant carbon
fibre and Supercar-style rear wing.
Brisbane Tuning and Turbo farmed out the job of laying up a new carbon bonnet
(with vents which are effective in cooling the intake manifold), front splitter
and Group A under-body rear diffuser. It’s all custom and magnificently
finished. The wiper arm surround panel, mirrors, front engine bay trim, valve
covers, fuse box and front strut bar are a mixture of genuine and imitation
carbon fibre. And the rear wing? Well, let’s just say it arrived together with a
reinforced boot from a very high profile race car.
Keen Holden fans might recognise the 18 inch wheels. These are the same as
slated for fitment to the stillborn 427ci (7-litre) production coupe and are
clad in Dunlop road/race rubber.
Inside, the trim is pretty much stock HSV GTS with splashes of aftermarket
carbon fibre trim. A boost gauge and nitrous level gauge are hidden away from
So where to next for this road-reg supercar?
Well, at the time of writing, a competition sump and diff cooler were being
stirred into the mix and there are discussions about upping the cubic capacity
count with an alloy 427ci-er. Doug plans to build the car that HSV never had the
guts to carry through with.
Oh, and we should mention that Doug has also bought a new HSV Coupe 4 (AWD)
that won’t stay standard for very long...
Brisbane Tuning and Turbo Centre
+61 7 3393 1588