Right Place, Right Time Rex

 

Working in one of Australia’s most experienced Subaru workshops – MRT Performance – has more than a few advantages. It’s the place to be when you want access to a treasure chest of STi and aftermarket parts and it’s the perfect environment to purchase a modified Rex. Chris Milne is one MRT Performance employee who has made the most of an opportunity to pick up a comprehensively in-house modified ‘bug eye’ WRX.

Chris says his WRX was modified about three years ago and carries the sort of aftermarket mods you’d expect from that time. All that he’s had to do is fine tune the suspension and handling, a bit of cosmetic work, improve the audio system and revert to a standard Subaru blow-off valve (the aftermarket valve that was installed attracted too much of the wrong kind of attention).

The previous owner recognized that achieving big power with the standard WRX 2-litre is a tall order if you want to retain useable torque and driveability. The solution was to drop in a MRT 2.2-litre stroker engine. That extra 200cc might seem relatively minor but it’s a 10 percent increase in total swept capacity - and every bit counts when you’re talking Subaru flat-fours. The turbocharger used on the 2.2 is a bolt-on VF30, which is considered pretty small for the application.

The VF30 compressor draws induction air through a MRT induction system and blows it through a MRT front-mount intercooler kit which incorporates a bar-and-plate core. Mandrel plumbing and high-temp silicon hoses are part of the front-mount upgrade. From the back of the VF30, exhaust gasses spill into a MRT dump pipe which leads to a high-flow cat and HKS Super Drager rear muffler. Exhaust pipe diameter is 3 inch.

MRT probably has more experience tuning WRXs than any other workshop in Australia and they’ve applied all their knowledge to the fuel system. Recognising a design limitation in the factory fuel system, MRT has modified the fuel rail arrangement to include twin pressure regulators to help maintain consistent mixtures from cylinder to cylinder. A set of 700cc injectors, a 500hp fuel pump and an MRT external surge tank are also installed.

Rather than rip out the factory management system and start tuning from scratch, MRT has employed EcuTeK tuning software to remap the factory ECU. The tweaked factory ECU is more than capable of providing appropriate mixtures, timing control, knock sensor characteristics, idle control and boost control.

With the EcuTeK tuned ECU set to deliver a big 21 – 22 psi boost, the stroked engine is pretty highly strung but there have been no problems in the 70,000km that have expired since the engine build. The car can push 262kW at all fours on MRT Performance’s DynaPack hub dyno. As a guide, a stock WRX puts out 110 – 120kW at the hubs...

Given the massive increase in top-end power and torque, you’d reckon the standard driveline would be trashed on a regular basis. Not so. An MRT and flywheel combo has lasted more than 70,000km without hassle and, even more surprisingly, the stock five-speed manual gearbox is untouched. The use of Redline gear oil and a level-headed driving technique work wonders. Interestingly, the wheel bearings and CVs have also been lubricated using NEO grease in preparation for some enthusiastic track work.

The preparations for track work have also lead to the fitment of almost everything from the Whiteline suspension catalogue. You’ll find a set of adjustable Group 4 struts, adjustable 22mm swaybars, alloy swaybar links, motorsport-spec anti-lift kit, rear sub-frame locking kit and a heavy-duty steering rack mount. There are also MRT adjustable front strut tops adjusted to provide double the amount of factory castor. The brakes aren’t mega-buck exotics but Chris says 15 laps of Wakefield (with Brett Middleton at the wheel) aren’t enough to fade the existing setup. Despite using ‘only’ the standard WRX four-pot calipers, the combination of DBA 5000 series slotted rotors and SBS Carbon Ceramic pads is well up to the rigors of track work. The only noticeable trade-off is some pad squeal in normal driving.

The bug eye Rex is pretty controversial from a styling point of view but chances are most people will identify this car as a STi (which, in our opinion, is a bit better looking). STi headlights with a HID conversion, a ’03 STi bonnet scoop, S202 carbon fibre rear wing, carbon fibre repeater panels, clear side indicators and full colour coding give the car a ‘factory tuned’ look. Works Emotion 18 x 7.5 inch rims and 225/45 rubber are also installed along with a list of brand name stickers down the leading edge of the front doors. Oh, and watch out for the ECUTEK number plates – no doubt well known around Sydney...

Inside, the Rex interior is enhanced with a Japanese-spec STi Defi instrument cluster (including factory shift light), A’PEXi boost, fuel pressure and EGT gauges, fire extinguisher, GFB quick-shift and Momo gear knob. Chris has also added a JVC head unit teamed with a MB Quart sub, Boston Pro front splits and a pair of Kicker amps.

At the time of writing, Chris has had only one opportunity to hit the track in his 2.2 WRX. The experience showed the engine has plenty of grunt, the chassis is well sorted (after some adjustments) and the brakes are capable of taking the punishment. But the tyres are another story – high quality performance tyres are at the top of Chris’ shopping list.

Perhaps the only downside of working at MRT is you’re constantly immersed in a sea of the latest and greatest hot-up hardware. And this has an inevitable affect. Chris is scheduling the fitment of an even bigger 2.5-litre engine with modified heads and cams, a larger turbo and a tweaked STi inlet manifold. If all goes to plan, the existing engine should ‘hold out’ and before being sold to fund the conversion to a STi six-speed ‘box and heavy-duty R180 rear-end.

Oh, and if bigger brakes are lying around the workshop...