Blitzing Them

The ChipTorque in-house development WRX.

by Julian Edgar

Click on pics to view larger images

When Subaru released the goggled-eyed WRX here in Australia, the buying public was universally underwhelmed. The car was bigger, heavier, slower and - most thought - uglier than the cult-classic preceding models. But in the US, the new model was the WRX that enthusiasts had been hearing about for so long - they didn't compare it with what had come before but gladly welcomed what they now had...

Because mechanically all WRXs have really been much the same (and the now quite old Liberty RS too for that matter), Australian companies have been in a position to capitalise on the huge US market by developing products for the new model that are based mostly on the intellectual property gained from modifying the previous shape! Confusing? Yes it is a bit, but it also explains why companies like MRT, APS and ChipTorque are moving mountains to develop and market WRX products for the States.

ChipTorque's own WRX is a good example. Bought to provide an in-house test vehicle for WRX product development (and also be a moving promotional advertisement for the Japanese-manufactured Blitz range of products that the company also sells), it's been modified with a very close eye to what will sell well in the US - and of course any local product sales are a welcome bonus.

Chief in the XS upgrade kit is the Xede (pronounced 'exceed', and yes, we know it's not spelt that way!) engine management modification module. An interceptor-style device (where the signals going in - and coming out of - the ECU are modified in a programmed way), it uses a plug-in harness. The factory wiring loom is unplugged from the ECU, plugged into the Xede, and the Xede plugged back into the ECU. It's neat, quick (ChipTorque charge nothing for installing an Xede - it's a 5-minute job!) and very importantly, easily removable. Buyers might want to take it back out when they send their car in for (hmmm!) factory servicing within the warranty period, or they might want to remove it when they sell the car.

The Xede alters the ignition timing, the fuel injector pulse widths, and the turbo boost values. However, long experience has shown that making just these changes alone doesn't give results nearly as good as making some specific, key mechanical modifications at the same time. An engine that breathes much better makes more power!

The car runs a heavily modified exhaust, starting from in front of the turbo. The factory cast iron exhausts feed into a new 2¼ inch ChipTorque stainless steel up-pipe, a design that retains the factory flexjoint but removes the Subaru squeezy bits. The pre-turbo cat converter is also deleted - not only does this improve flow but it also prevents this cat ever falling to pieces and passing through the turbine - yes, this cat is in front of the turbo, remember! The threaded boss - for what ChipTorque tell us is an exhaust temp sensor - remains in place. Out of the turbo the exhaust flows into a 3-inch hi-flow catalytic converter (complete with 3-inch flex) and then into a 'cat-back' Blitz rear system, including muffler.

The new exhaust reduces backpressure and gives better transient response - and does all of this without being at all objectionably noisy. The flat four of the WRX - with its oh-so-characteristic note - can easily degenerate from a burble to horrible noise, but this exhaust really does tread the fine line very well.

The standard under-bonnet intercooler is retained. Despite some people's claims otherwise, putting an intercooler on top of an engine (and almost on top of the turbo!) is a bloody awful place for a heat exchanger, but the fitting of a front-mount involves lots of plumbing, often some bumper cutting - and quite a lot of expense. One of the beauties of doing a full kit for the WRX is that the engine management tweaks can take into account the type of intercooling that's being used, so for example in the case of the Xede kitted car, turbo boost is allowed to swell in the midrange, but is pulled back as revs then grow. This allows heat to be dumped into the 'cooler then as intake air temp rises, boost is reduced - safe and conservative.

However, the underbonnet intercooler install is tweaked a little - the pictured ugly-looking plastic Y-junction pipe that feeds turbo'd air to the core is upgraded with a smoother flowing cast alloy design, which comes complete with silicone hoses.

To improve intercooler efficiency, a water spray is also fitted. This uses the factory wagon washer bottle - that already comes complete with two pumps - in place of the standard bottle, with the spray intelligently triggered by the Xede. Finally, a K&N filter element is fitted in the standard airbox.

The XS kit takes power up from 105kW at the wheels (measured in 2WD on the notoriously lossy Dyno Dynamics machine) up to 135kW - a gain of 29 per cent. Importantly, power is improved right through the rev range, although it's from 3000 rpm where the new power curve really takes off. The kit costs AUD$4150 - and around AUD$450 to have it fitted.

That's the normal kit, but the ChipTorque WRX also runs a major engine difference - a larger VF23 turbo is fitted. This isn't to say that the recommendation is to fit a VF23 - in fact ChipTorque suggest that if a turbo upgrade is required, a VF29 is preferable on a street driven car. So why the VF23? Well it's kind of a long story, but remember that pre-turbo cat we mentioned above? Yep, you guessed it - during development that cat decided to come to pieces and go right through the fragile turbine blades of the original turbo... The VF23 was available, and so on it went.

We were able to drive the car and see how well the package - in this form - came together. First up, though, we gotta say that we think the recent roundup of Subaru turbo models really aren't anything cutting edge anymore. The standard STi has unacceptable turbo lag, and even the base model is much flatter down the bottom than any modern turbo car should be. So fit a bigger turbo and even with the exhaust, intake and engine management mods, you'd have to be a believer in miracles to think that down the bottom end the car will go like a Nissan 200SX - let alone something like a sequential twin turbo Supra.

That said, it wasn't too bad at all. Off-boost it was tractable and at least reacted to throttle inputs, while on boost it was s-t-r-o-n-g. (The car a few weeks later ran a 13.5 quarter mile with a noticeably slipping clutch, and certainly felt every bit a high 12-second car when we drove it.) The transition from atmo to turbo was progressive and smooth, and the boost curve behaved exactly as it was supposed to - peaking in the midrange at 21 psi then progressively being pulled back to 16 psi as revs rocketed to the redline. Importantly, this car didn't have the boost fluctuation concerns that we experienced in the previous model ChipTorque in-house development WRX that we drove - flooring it in a high gear didn't see boost rocket uncontrollably.

The car is used by ChipTorque's Lachlan Riddel as his family car, and it literally does the pick-the-kids-up-from-school each day without any hassles at all.

In fact, in terms of the exhaust note, driveability, and boost control it came together as a good package.

Ah yes, but as a Blitz promo vehicle there're also a few other goodies bolted on. You'll find Blitz oil and radiator caps, a new silicone top radiator hose (which has a built-in nipple to take a Blitz coolant temp sensor), stepper motor Blitz coolant and boost gauges, and an intelligent Blitz turbo timer, which sets the idle-down time depending on how the car has been driven. Oh yeah, and a Blitz gearknob is where you'd expect it to be and a Racing Meter DC's stuck to the windscreen. The car's been dumped a bit with super-low King front springs and just-low King rears, and for the shoot was wearing ROH 17's with Federal 215/45s. (Mega-expensive Blitz alloys are on their way.)

And all of those stickers? Lachlan is unapologetic. "It's a promotional car and people need to notice it!"

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