Ever watched a child go off the rails when they’ve found something that they really, really want? You’ve probably seen the furrowed brow, the pouting, flailing arms and the obnoxious whines of “I wannit, I wannit, I wannit!”
Well, that’s how we feel when we see the HSV Coupe 4 owned by Geoff Thuring of JHP Vehicle Enhancements. This is a car that we’d gladly keep forever. We wouldn’t ask for anything ever again – honest...
It’s this sort of reaction (or something like it!) that Geoff aims to generate with his Coupe 4 – it’s the perfect promo tool for his Melbourne-based vehicle enhancement business. Geoff has had plenty of HSV vehicles in the last 10 years and says, from a business point of view, it pays to have the latest and greatest model to promote and develop.
“I bought the Coupe 4 in 2004 because it was the pick of the range and it had all-wheel-drive to get the power down,” says Geoff.
As you may be aware, the Coupe 4 comes with all of HSV’s good bits, AWD and stomps out 279kW. Still, Geoff says the standard Coupe 4 car felt down on performance compared to the previous HSVs he’d owned. The auto transmission and AWD system (which takes the kerb weight to around 1800kg) take some shine off the performance.
“I looked at adding more power in what I describe as a conservative fashion,” says Geoff. No booming exhaust or lumpy idle here.
The product that got the nod is the Harrop Stealth blower kit which boosts the LS1 to around 7 psi. The Harrop kit includes a LS112 supercharger with Eaton rotors, a replacement intake manifold, heavy-duty belt system, replacement intake duct, base ECU program and an optional water-to-air intercooler that’s tucked in the valley. Geoff also went for the optional 92mm throttle body and bigger injectors. The kit was fitted and given a final tune in-house at JHP Vehicle Enhancements – Geoff says the conversion (exactly as fitted to his Coupe 4) cost AUD$10,500 drive in/drive out.
Interestingly, Geoff has resisted the urge to whack on a complete aftermarket exhaust system. True to the plan to keep the car conservative, he has kept most of the standard HSV exhaust but installed free-flow intermediate mufflers and modified rear pipework.
With the supercharger installed, Geoff’s Coupe 4 has picked up around 100kW at the wheels. With normal 98 RON fuel in the tank it has punched out 289kW at all four wheels on a Dyno Dynamics chassis dyno. Straight-line performance has not yet been confirmed but Geoff says a high 12 is a realistic expectation given the standard car runs low 14s.
“The car launches great,” says Geoff.
“It just bites and takes off,” he says.
The auto transmission (the Coupe 4 was auto-only) boasts a big fluid cooler and reprogrammed shift patterns. The driveline is standard aside from fitment of a HSV LSD in the rear. This reduces the traction control that is applied to the rear wheels on hard launches.
To improve the Coupe 4’s on-road feel and race circuit performance, Geoff installed a set of JHP Stage 3 adjustable height, bump and rebound coil-overs in the front and adjustable height coils and race dampers in the rear. These give a huge range of adjustment from Statesman-soft to hell-this-is-hard.
The HSV Coupe 4 uses the same RWD-bias AWD as found in the Holden Adventra. The system employs traction control and individual brake calipers to prevent wheel spin and apportion torque to the wheel(s) with the most grip. Following fitment of the rear LSD, Geoff is currently in the process of installing switchable traction control – this is hoped to provide greater driver control.
The brakes are standard HSV fare except for braided lines, grooved rotors, performance pads and fluid. This combo is fine for the street but can’t hack the pace on the circuit - Geoff plans to step up to Harrops.
The sleek body features subtle modifications. Geoff has added a VZ Monaro bonnet together with a custom modified rear bumper. The bumper now incorporates a mesh section which Geoff says was fitted to the original HSV Coupe 4 show car.
Wheels are the standard Coupe 4 19s – why change ‘em when they look this good? But Geoff has switched to a larger rear tyre – you’ll find 275mm rear rubbers in place of the standard 255s. Oh, and Pirelli P-Zeros are the tyre of choice.
About now you may be wondering about the wheel arch flares, side skirts, rear spoiler and sexy front bar. Well, it’s all standard – HSV held nothing back with the Coupe 4!
Open the long doors and you’ll find the standard 2004 Coupe 4 interior – again, why modify when there’s no need? The 2-tone leather trim, drilled pedals, white face instruments and a gauge pod (for battery voltage and oil pressure) make every trip an enjoyable one.
Selling for AUD$89,950 when new and with more than 10 grand spent on modification, Geoff’s Coupe 4 isn’t exactly a cheap performance car but it’s one that will happily chew up Porsches and spit ‘em out. Understandably, Geoff is pretty fond of this machine but admits he needs to move with the times and update into the latest 6.0 litre HSV.
So what happens to the blown Coupe 4?
Well, get your best pouting face ready coz this sucker is now for sale!
Please can I have 88 grand to buy a toy? P-l-e-a-s-e....