Power Pages: 2002 Subaru WRX

When we last left off our Subaru boasted 219.7 horsepower and 222.4 lbs-ft of torque. Our bolt-on components at this point consisted of an array of XS Engineering parts. We started off with an air intake, exhaust and APEXi S-AFC then installed the company's off road front and mid down-pipes as well as upping the boost to a max boost pressure of 15 psi with the use of an APEXi AVC-R.

The Engine
As we stated at the end of our Part II segment, detonation was audible which put an end to any further dyno testing until we could drop the intake temperature. Before that, all the horsepower was made utilizing the factory air-to-air intercooler.

Performance Components
For our third at bat our arsenal consisted of a two-part power page. Seeing how the vehicle is new of 2002 parts availability is still an issue. Although we only have two parts in this segment the two power adders will play a key issue in future chapter of this power page WRX. First we added an XS front mount intercooler as well as an XS built IHI turbo.

At the end of our last session the detention told us that we were on the borderline of power or breakage if we didn't swap out the OEM intercooler. The main reason we pointed the finger towards the intercooler was because the longer we cooled the car down the more detonation disappeared. We enlisted the help of an XS intercooler as well as their piping kit for the WRX. The intercooler is 3x18x10-inches in size while piping comes in a 2.25-inch diameter. Since the factory intercooler housed the OE blow off valve this required the XS intercooler kit to utilize an aftermarket unit. The mild steel piping is powder coated and all clamps and silicone connectors are provided.

The IHI turbo mimics the same design as the WRC Subaru minus the restricter plate. Additional hoses, clamps and gaskets are included with the turbo as well as a new upper pipe to accommodate the larger outlet on the new unit. The turbo's main objective is to produce a healthier mid range with out sacrificing much horsepower on the top end. XS Engineering has also informed us that there is a larger unit on its way that will be released in April.

Dyno Testing
When we left off our horsepower was at 219.7 at 6000 rpm. With the boost set at 15 psi using the AVC-R we were able to build most of the power in the mid range section of the power band. Along with the impressive horsepower the vehicle was also able to produce a healthy 222 lbs-ft of torque.

With the XS intercooler installed and the boost controller locked on 15 psi we were able to find out how much power the intercooler was able to generate by lowering the air charge temperature. We would like to note that the use of the XS Engineering intercooler kit removes the factory fog lights since intercooler piping has limited routes. Although we lost the fog lights we were able to pick up an additional eight ponies in the peak range as well as an extra 8 to 20 horses from 4000 to 5500. Torque also picked up as much as 25 lbs-ft at 4300 rpm.

Conclusion
Adding the IHI turbo was very easy considering it was a factory replacement. To ensure accuracy of the horsepower comparison the boost was left at 15 psi to test the effectiveness of the turbo. The turbo delivered exactly what it was intended to and the proof was the 20 horsepower gain in the 3000 to 4600 area. The sacrifice at the top end was a mere two horsepower.