The 2008 Subaru STI is a legendary car, renowned for its performance and rally-bred heritage. For enthusiasts looking to push their STI to the limit on the track, a series of targeted upgrades can transform it into a formidable machine. This article delves into the journey of modifying a 2008 Sti for optimal track performance, drawing inspiration from real-world modifications and focusing on key areas for improvement.
One of the first areas to address when building a track car is the suspension. The stock suspension on a 2008 STI is capable, but for serious track use, upgrades are essential. Switching to performance coilovers, like BC-BR models, provides adjustable ride height and damping, allowing for precise tuning of the car’s handling characteristics. Complementing the coilovers with new Lower Control Arms (LCAs) and stiffer bushings, such as Whiteline bushings in the front LCA’s, further enhances stability and responsiveness. Notably, later model STIs featured upgraded LCAs, highlighting Subaru’s own continuous improvement of the platform. For visual appeal and to denote the upgrade, painting the new LCAs red can mirror the aesthetic of performance aftermarket parts. Adjustable rear control arms are also crucial for fine-tuning alignment settings for track conditions.
Moving beyond suspension, engine modifications are key to unlocking the full potential of a 2008 STI on the track. Improving engine breathing is a common and effective modification. “TGV deletes,” which involve modifying or removing the Tumble Generator Valves in the intake manifold, streamline airflow into the engine. Porting and smoothing the injector bodies and matching them to the manifold and heads further optimizes intake flow. To ensure robust engine performance under track conditions, upgrading the oil pan to a Moroso aluminum pan and installing stiffer motor mounts are wise choices. These mounts reduce engine movement, improving handling and drivetrain responsiveness, although installation can be challenging due to limited space. An oil filter bypass block is another useful addition, simplifying oil system modifications.
For enhanced cooling and oil pressure management, a high-performance oil cooler is a vital upgrade for any track-focused 2008 STI. A Setrab cooler, known for its efficiency, can significantly reduce oil temperatures, crucial for maintaining engine reliability during demanding track sessions. An Accusump, a pressurized oil reservoir, provides an extra layer of protection against oil pressure drops, especially during high-G cornering on the track. Fuel delivery also needs to be addressed when increasing engine output. Upgrading to a higher volume fuel pump, such as a Walbro 255, ensures adequate fuel supply for increased power demands.
Further power enhancements for a 2008 STI track car often involve turbocharger and supporting modifications. Upgrading to a Blouch Dominator 2.5 XT-R turbocharger, with a 3″ air inlet and 8cm turbine A/R, can deliver substantial power gains. To match the increased airflow, larger injectors, such as Injector Dynamics 1000cc injectors, are necessary. Fuel pump upgrades may need to be revisited, potentially moving to a Walbro 450 for higher horsepower builds. An Aeromotive A1000-6 bypass regulator ensures consistent fuel pressure. An Agency Power 3″ polished aluminum hard turbo inlet and a KS Tech MegaMAF 73mm Big MAF Cold Air Intake maximize air intake. A Turbo XS type FMIC (front mount intercooler) further cools the intake charge, increasing density and power. A Grimmspeed Electronic Boost Control Solenoid (EBCS) allows for precise boost control, and colder spark plugs, like NGK Iridium IX LFR7AIX # 2309, are recommended for higher boost levels and track use.
Optimizing the oil cooling system is paramount for track durability. A Setrab 40 row oil cooler, combined with a Mocal OT2 thermostat bypass valve and a Canton rotating remote oil filter adapter, creates a robust and efficient oil cooling setup. Replacing the stock oil heat exchanger with a Canton adapter plate and utilizing AN lines with Mocal hose ends improves oil flow and cooling efficiency. A Canton remote oil filter mount, designed for Ford-style filters like K&N HP 3001, allows for easier filter changes. An Accusump and an upgraded oil pan, such as a KillerB pan with windage tray and pickup tube, further safeguard the engine. An air-oil separator (AOS) system, like a Crawford A/OS, prevents oil from entering the intake, especially important under track conditions, and venting it to a catch can like a JEGS breather tank ensures proper crankcase ventilation. Finally, a Fluidampr crank pulley replaces the stock Perrin pulley, offering improved engine harmonics and durability.
To monitor critical engine parameters on the track, installing gauges is essential. SPA Technique dual/digital gauges can display oil pressure, oil temperature, water temperature, and boost, providing real-time feedback on engine health and performance.
Transforming a 2008 STI into a track-ready car involves a comprehensive approach, addressing suspension, engine performance, cooling, and monitoring systems. These modifications, inspired by dedicated enthusiasts, demonstrate the potential of the 2008 STI platform to become a true track weapon. By carefully selecting and installing performance upgrades, owners can unlock exhilarating track performance and enjoy the full capabilities of their 2008 STI.
