How to create a Super Fun WRX STI

Author: Julius Bloem  Date Posted:21 May 2018 

It's easy to lose sight of what makes a car fun and enjoyable to drive on the road. Whilst there is no doubt having stupid amounts of power is exciting, it's not always sensible, usable, affordable or reliable.

More power is not always the answer in building a fun-to-drive car!

It's easy to lose sight of what makes a car fun and enjoyable to drive on the road. Whilst there is no doubt having stupid amounts of power is exciting, it's not always sensible, usable, affordable or reliable. Through the experience gained from building countless cars over the years, we've found that mildly modified vehicles often the most enjoyable and fun to drive. To make things even better, they maintain simplicity, reliability and are more affordable to build, drive and maintain. When Simon turned up with his 1999 WRX STI (Version 5/6) - this is exactly what he had in mind. Simon had owned the car for many years, and had already installed a downpipe and previously had PBMS install and tune a Link ECU. In the back of his mind, Simon had been thinking the engine was a little down on power, so a rebuild, with a few enhancements was planned.

Before

To get a gauge on the performance increase we'd end up with, we threw the car on the dyno for a 'before' power run. Modifications: 2.5 inch downpipe Link ECU G4 Result: The car spun up a very lacklustre 165kw at the wheels. Although the car the was mildly modified, this seemed a little lower than we would have expected.

The Plan

Keep it simple and make something fun! A very simple combination comprising of the best STI factory components was put together. This included a brand new VF22 turbo and Version 11/GRB STI intercooler customised to suit. Aftermarket parts added were pretty basic including a full 3-inch stainless exhaust fitted with a stock-looking rear muffler. A higher flow intake pipe was fitted, with a custom PBMS tube connecting to the factory cold-air box that housed a high-flow K&N filter.

The most economical way to meet the power goals reliably was to fit a brand new EJ207 shortblock kit, and rebuild the cylinder heads. Under the hood, special attention was paid to keep it looking like factory, only better. This included a re-painted intake manifold, plated bolt kit and a general tidy up.

A twist to the plot...

Or more of a bend. Upon stripping of the original engine, we found a bent con-rod. This likely explains the lower-than-expected 'before' power level.

Engine Modifications (Initial stage)

Link G4 ECU VF22 STI turbo V11/GRB Top mount intercooler 3 inch stainless steel exhaust Aftermarket intake pipe AEM 300LPH fuel pump K&N Panel filter  

Results

Note: Tuned on BP 98.

We got exactly what we were hoping for. FUN! The factory turbo and short piping of the top mount intercooler makes for responsive and easy to drive engine package. Driving it around town, the turbo starts making a noise by 2500rpm, and a stab of the throttle sees the car pulling by 3000rpm. The power band only gets better, producing a peak power of 237kw at 6700rpm. The off/on throttle response is like a light switch, perfect for getting power down out of corners, or over taking when required. In the light GC8 chassis, this package is incredibly fun, drivable and exhilarating through the twisties or around the racetrack. Our favourite part of Simon's build has been the attention to detail. It looks unassuming from the outside, and under the hood it looks better-than-new!


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