SAFE AND SOUND
Keen to find out how well turbocharged VXRs can cope with big power, Callan Ackerman subjected this Arden Blue Astra to a wealth of upgrades in the pursuit of 550bhp…
Callan Ackerman subjected his Astra VXR to a wealth of upgrades in pursuit of 550bhp.
What is it that first drew you to Vauxhalls? For Astra owner, Callan Ackerman, it was the noise! “I must admit, I wasn’t overly impressed with the Mk5 VXR before a mate took me out for a spin in his lightly tuned example. Up until that point in time, I’d been modifying cars from the stables of a variety of different manufacturers. A Renault Megane R26, a Seat Leon Cupra R, a BMW E36 drop-top and even a 530D were just some of the cars I’d bought and tuned. I’d heard horror stories about the VXR’s engine and transmission reliability when subjected to a significant hike in horsepower, but the pops and bangs my friend’s car was making, not to mention how quick it felt, convinced me I needed to find out how good or bad Astra VXRs are first-hand.”
“At the back of my mind, I liked the idea of fitting a turbocharger capable of producing more power,” says Callan. “I tried to exercise restraint by buying a freshly built K06, but I was amazed at the claimed 620bhp being delivered by the BorgWarner S257SX-E T3 twinscroll turbocharger fitted to a
Mk4 Astra GSi I’d been reading about. When the owner of the car offered the part for sale, I couldn’t resist, although if anything was going to test the durability of my car’s engine and gearbox, this was more than likely it!”
Providing the voice of reason, Dale stressed the need for Callan to buy a stack of essential supporting equipment if he stood any chance of being able to make use of his new snail-shaped bhp booster before the car’s engine blew itself up. “I was suddenly faced with a lot of unanticipated spend,” sighs the scaffolder from Bristol. “The block needed to be wedged, the cylinder head needed to be overhauled, I had to buy high-flow fuel kit, a new exhaust, all new intake equipment and a mass of other performance parts. The list was huge!” he gasps, although he’s the first to admit Dale knows a thing or two about building engines for VXRs chucking out big bhp, as evidenced by the high number of reliable, supremely powerful Astras which have rolled out of the Autoworks Services workshop doors of late.
Depending on which way you look at it, chasing ponies and buying a bigger turbo may have saved Callan money in the long run. “After I gave the green light to Dale to start work on the engine, he contacted me with news the cylinder head featured a bent valve and one of the main bearings was severely worn. In short, I’d bought a ticking time bomb,” he groans. At least the problem was discovered before major damage was done, allowing Dale to continue stripping the engine of its internals before decking the block and rebuilding with Omega oversized forged pistons, PEC connecting rods, ARP fasteners, Mahle bearings, a balanced crankshaft and Vaux Pro wedges. The head was cleaned and rebuilt with new valves, Piper springs, fresh stem seal retainers and Regal Autosport RSS camshafts.
GO WITH THE FLOW
The demand for high fuelling was met by Injector Dynamics 1050cc fuel injectors and an ASNU fuel pump, while the turbocharger benefits from a Nortech Performance tubular exhaust manifold, twin Turbosmart wastegates, a Turbosmart Race Port and large-bore airflow pipework, including a Nortech downpipe, a three-inch Cobra double-decat exhaust, an Airtec Gobstopper intercooler, an EDS inlet manifold and a custom intake mated to an AEM open cone air filter.
The stock M32 six-speed ‘chocolate box’ remains, albeit bolstered by a TTV Racing lightweight billet flywheel and a six-paddle clutch made specifically for Callan’s car by the guys at Helix. Vibra Technics gearbox and engine mounts eliminate any unwanted movement from the drivetrain, while a Quaife ATB limitedslip differential will help the car to make use of the 550bhp he hopes to witness the car produce during a mapping session at RnD Motorsport following the writing of Rabbid base map software currently limiting power to a safe 365bhp.
“The diff went on not long after I bought the car,” reveals Callan. “I’ve
now experienced seat time in a variety of Mk5 Astra VXRs, and all of them like to spin their wheels, even on what you might consider to be a low output map. Standard VXRs aren’t much better! I reasoned Stage 3 without a limited-slip differential would be undriveable. The Quaife unit has completely transformed the way my car behaves, enabling me to get the power down without fear of losing traction as soon as I hit the throttle,” he says.
Determined to drive a track- friendly weekender, he replaced the car’s Lotus-tuned factory suspension with Bilstein B14 coilovers and a Whiteline adjustable rear anti-roll bar. Solid subframe mounts will be fitted not long after the car arrives at RnD’s Yorkshire headquarters. The unappealing rims Callan inherited with the car are long gone, replaced by super-light Team Dynamics Pro Race 1.2 eighteen-inchers with streetlegal Yokohama track tyres. KSport eight-piston brakes can also be spotted at the nose end of the car. Finished in piercing yellow, they’re difficult to miss behind the gloss black spokes, but even giant, brightly coloured brakes struggle to lay claim to being this ace Astra’s defining feature. That honour must surely go to its radically vented bonnet.
ON THE NOSE
“A fellow Astra VXR owner, Anthony Marsh, had the bonnet fitted to his car long before the part was added to mine,” admits Callan. “I asked Anthony to let me know if he ever fancied selling what is a unique panel based on an original VXR metal bonnet. Eventually, I commissioned a body shop to install similarly big vents into a bonnet I bought specifically for the job. Just as the work was about to begin, however, Anthony told me he was putting his VXR back to standard specification. Pleasingly, he gave me first refusal on his Astra’s custom bonnet. I didn’t need to be asked twice!”
It’s certainly an eye-catching addition to Callan’s car, but he’s
“I’VE MADE ENQUIRIES REGARDING HAVING THE BONNET MADE OUT OF CARBON-FIBRE”
KSport eight-pots are difficult to miss
An RnD Motorsport mapping session should release plenty of presently stifled ponies