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...
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