unusual to find a car enthusiast who is 100 percent content with their machine.
There are always some shinier wheels, bigger cams and sexier sub-woofers to
catch you eye just when you thought you had everything sorted out... Well, Simon X is an exception. His
sensational HSV GTO has everything he desires and he’s not interested in
updating to the latest model.
happy right where he is, thanks very much!
car was featured in AutoSpeed back in 2002 (see Fly the Coupe)
and since then it has comprehensively matured as a performance vehicle. Every
area of performance has been addressed.
last time we saw this GTO it was running a cam and head package good for 271kW
at the wheels. Simon says he spent a fair amount of time with different cam
profiles chasing the power he wanted - Simon is a regular circuit racer and
doesn’t like the idea of being left behind on the straights...
a really big cam in it the car made good power - but there’s a limit to what you
can do by just changing the cam in the standard 5.7,” says Simon.
big horsepower camshafts caused a bottom-end torque loss that Simon wasn’t
content with so the next logical step was to bump up the cubic capacity (Simon
isn’t a fan of forced induction). At this point, Simon sat down with F1
Performance’s trusted engine builder - James Young - and discussed approximate
power output and engine application. There wasn’t a particular power figure
Simon had in mind – he simply wanted an engine that could be driven without
hiccup in traffic yet perform strongly on weekend racetrack assaults.
solution came in the form of a 6.2-litre (383ci) Eagle stroker kit teamed with
heavy-duty L19 rod bolts and JE forged pistons providing a 10.8:1 compression
ratio. The already ported cylinder heads were replaced with even more serious
heads with bigger ports and polished combustion chambers. The camshaft is a big
‘un with specifications chosen by James Young. Stainless steel valves,
Competition valve springs, heavy-duty retainers, 1.7:1 Yella Terra roller
rockers and a Rollmaster double row timing chain complete the valvetrain.
Multi-layer head gaskets are also used in the build.
huge volume of gas exhaled by the stroker motor is channeled through a twin 3
inch Di Filippo exhaust with a custom rear muffler with an emphasis on reducing
noise. Simon doesn’t want to attract the wrong kind of attention on the street.
A pair of ceramic-coated Pacemaker 4>1 headers scavenge gasses from the
the intake side, an over-the-radiator ram-air pipe draws air through a removable
K&N panel filter. Downstream of
the ram-air pipe is a Starr throttle body connected to the stock intake
says the newly built stroker motor delivers strong punch from about 4500 to 6800
rpm - 200 rpm shy of the rev limiter. The reset rev limit, altered fuel mapping
and ignition timing come courtesy of LS1 Edit reprogramming software. No need
to fiddle around wiring in a new computer or interceptor unit.
of those long-sweeping pistons suck fuel from a 42lb fuel injector teamed with
Wilson Manifolds rails, braided lines and an SX pressure regulator. A Bosch 044
Motorsport pump and surge tank live in the rear and guarantee uninterrupted fuel
delivery even during the fiercest cornering and braking forces.
into life on F1 Performance’s Dyno Dynamics chassis dyno, Simon’s GTO makes some
impressive numbers. There’s bulk torque straight off idle and the muscle
continues to flex to almost 7000 rpm where the car is pushing 355kW at the
treads. That equates to almost 450kW at the crank – enough to see off pretty
well anything that lines up alongside.
further along the driveline you’ll find a 12 inch Mal Wood clutch and Yella
Terra lightened steel flywheel. The stock T56 gearbox was also replaced by a Mal
Wood 6-speed ‘box with carefully selected ratios. A Mal Wood tailshaft reaches
back to the rear-end which is enhanced with a KAAZ mechanical LSD. A Harrop diff
cover (which provides greater fluid capacity and improved cooling) is also
the original 5.7 litre engine, Simon says the GTO handled progressively and was
easy to control. But with stroker grunt now on tap, the car arrives at corners
carrying a lot more speed and the handling needed more development. Previously,
the car used a Quadrant/Bilstein set-up comprising springs, dampers and a front
strut brace. It now uses Koni double adjustable dampers, King springs, Nolathane
bushes and a Whiteline adjustable front swaybar. The chassis is also toughened
with the addition of a rear strut brace and under-body bracing.
existing Harrop/DBA front brakes are carried over but Simon says a pair of
six-pot CSC anchors will be soon fitted. The rear employs newly installed CSC
four-pot calipers and slotted discs. Simon says the CSCs are a great product –
they provide good value for money, good disc life and they stop well. A set of
Race Brakes RB74s are used for the street while circuit duties call for PFC
Simon also tweaks the chassis before each track day. Up to 4½ degrees of
negative camber and 1.5 – 3mm of toe-out improves front end turn-in and mid
corner grip. Front brake cooling ducts are also installed and the
Monday-to-Friday Nexen tyres are swapped for soft an’ sticky Bridgestone RE55s.
preparation for track work includes the fitment of an engine oil cooler and
power steering fluid cooler. It’s this kind of attention to detail that makes
Simon’s GTO very quick and reliable – it’s no surprise that the car was the
quickest road car at Winton Raceway during a recent weekend meet.
keeps an eye on the engine thanks to AutoMeter gauges for oil pressure and
temperature. These are temporarily mounted in a custom alloy faceplate at the
base of the centre console. They will soon be integrated into an OE satellite
navigation trim panel.
audio system stems from gold plated battery terminals and fuse holders into the
standard HSV head unit. An Eclipse four-channel amplifier boost the output level
and sends it to 6½ inch Focal front splits, 5 1/4 inch Focal rear splits and a
pair of Rockford Fosgate 6½ inch woofers in the rear shelf. Simon chose these
as a lighter weight alternative to large cone subs and says they work well -
especially in the mid-bass frequencies. Sound deadening is installed inside the
doors and side quarter panels to improve sound quality.
around three years of development, Simon has his GTO exactly how he wants it –
there’s no way you could tempt him with the latest batch of Holden/HSV Coupes.
The only plan on the agenda is to put a higher number on the odometer – when
you’ve finally pieced together your dream machine, you often find there’s simply
not enough time for drivin’ it...
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