The FA20 Platform and the 350 HP Target

Subaru's FA20 engine, found in models like the BRZ, Toyota GT86, and Subaru WRX, is a robust and responsive powerplant that responds exceptionally well to forced induction. While the naturally aspirated FA20 produces around 200 horsepower, the engine's closed-deck design and forged internals in later iterations make it a solid foundation for a 350+ horsepower build. Reaching this power level requires a careful selection of components and a realistic budget, but the goal is entirely achievable for under $5,000 if you prioritize wisely and understand where to allocate funds for maximum gains without sacrificing reliability.

For many enthusiasts, the 350-400 horsepower range represents a sweet spot where the car becomes genuinely quick on both street and track without requiring a full engine rebuild or exotic fuel systems. This power level transforms the driving experience while keeping the car daily-drivable and manageable. The key is understanding that forced induction is not just about bolting on a turbo—it's a system that requires careful integration of air, fuel, and spark management.

Understanding Forced Induction Options for the FA20

Before diving into the cost breakdown, it is critical to understand the two primary forced induction paths available and how they affect your budget and driving experience. Each approach has distinct advantages and trade-offs that will influence your component choices.

Turbocharging vs Supercharging

Turbocharging uses exhaust gases to spin a turbine that compresses intake air. This is the most common and cost-effective path to 350+ HP on the FA20. A correctly sized turbo can deliver excellent top-end power and efficient spool for street driving. Turbo kits for the FA20 are widely available and relatively straightforward to install, making them the preferred choice for budget-minded builders.

Supercharging uses a belt-driven compressor to provide immediate boost response at low RPM. While supercharger kits offer linear power delivery and instant throttle response, they are generally more expensive and more complex to install on the FA20. Achieving 350+ HP with a supercharger often requires a larger unit or higher boost levels, which drives up costs and heat management requirements. For the sub-$5,000 target, a turbocharger setup is almost certainly the more practical and cost-effective route.

For a detailed comparison of turbo options specific to the FA20, resources like FT86 Club's forced induction forum provide real-world owner experiences and dyno results that can help narrow down your choice.

The $5,000 Budget Spreadsheet: Breaking Down Every Dollar

The following breakdown represents a realistic, track-proven path to 350+ HP on an FA20 using a turbocharger system. Prices reflect current market averages for quality aftermarket components as of 2025. The goal is to build a reliable system with no shortcuts on critical safety components while staying under the five-thousand-dollar cap. This budget assumes you already own a healthy, stock FA20 engine in good condition and that you will perform the installation yourself.

1. Turbocharger and Manifold Kit: $2,200 - $2,800

This is the single largest expense and the component where quality matters most. You need a complete kit that includes the turbo manifold, wastegate, downpipe, and all necessary gaskets and hardware. Avoid generic universal turbo setups, as the FA20's tight engine bay requires specific piping to avoid clearance issues with the steering column and oil pan.

Recommended kits designed specifically for the FA20 include offerings from companies like JDL Auto Design, Full Blown Motorsports, and PTuning. These kits typically include a precision-machined manifold that ensures proper wastegate placement and minimal turbo lag. The turbocharger itself should be sized for your power goal—roughly a GT2860RS (Garrett) or a Precision 5858 are excellent choices that spool quickly and support up to 400 wheel horsepower. Buying a complete kit from a single manufacturer often saves money compared to piecing together individual components and ensures compatibility.

If you find a reputable used kit in good condition, this is one area where buying second-hand can significantly reduce your total cost without sacrificing quality. However, inspect the turbocharger for shaft play and the manifold for cracks before purchase.

2. Intercooling System: $350 - $700

Cooling the compressed air is non-negotiable for reliability and power. The FA20 is sensitive to intake air temperatures, and hot air promotes knock and reduces power output. A front-mount intercooler (FMIC) is the standard choice for turbocharged FA20s and offers better cooling efficiency than a top-mount (TMIC) setup due to its position in direct airflow.

Look for a bar-and-plate intercooler core, which is more efficient than tube-and-fin designs. Kits from Mishimoto or Process West are popular choices, but budget-friendly options from CXRacing or Godspeed Project can deliver adequate cooling for the 350 HP level if you upgrade the piping and couplers. Ensure that the kit includes all necessary piping, silicone couplers, and T-bolt clamps to prevent boost leaks. A properly sized intercooler with good airflow will also reduce charge air temperature by 40-60 degrees Fahrenheit, directly translating to more consistent power.

3. Fuel System Upgrades: $600 - $1,100

Your stock fuel system was designed for 200 horsepower. To safely support 350+ HP, you must increase fuel delivery. At this power level, the stock high-pressure fuel pump (HPFP) on DI FA20s can struggle to maintain pressure, so upgrading the injectors and potentially the low-pressure fuel pump is necessary. There are two main approaches:

  • Direct Injection Only: Upgrade to larger direct injectors (e.g., Injector Dynamics ID1050x or DeatschWerks DW800) and a higher-flowing low-pressure fuel pump (such as a Walbro 450 or 525). This path retains the stock fuel rail and is simpler for DIY installs. Estimated cost: $600-$900.
  • Port Injection (PI) as Supplemental: Adding port injectors alongside the stock direct injectors provides additional fuel capacity and helps keep the intake valves clean. This requires a PI manifold, fuel rails, injectors, and a standalone controller. While more expensive ($1,000-$1,500), this setup offers the best fuel distribution and future growth potential. For strictly staying under $5,000, the DI-only route is more practical, but be prepared to upgrade the fuel pump if you run higher ethanol content (E85).

Do not skip fuel system upgrades. Running lean under boost is the fastest way to destroy your FA20. IWSTI's FI conversion discussion has extensive threads on injector sizing and fuel pump requirements for various power levels.

4. Engine Management and Tuning: $600 - $1,200

Without proper tuning, your new turbo kit is just expensive engine jewelry. The stock ECU cannot handle the increased air and fuel demands of forced induction, and a poor tune can cause detonation, pre-ignition, or melted pistons in a matter of seconds. You have two primary options for tuning the FA20:

  • ECUtek: This is the most common and powerful tuning solution for the FA20. It allows for full control over ignition timing, fuel maps, boost control, and safety limits. ECUtek comes in various license tiers, with the ProTune license being the standard for custom tuning. You will also need a cable and software license, which can be purchased from a licensed tuner. Total cost for license, cable, and professional tune: approximately $800-$1,200.
  • Cobb Accessport: The Accessport is a popular user-friendly platform with off-the-shelf (OTS) maps and the ability to run custom tunes. The device itself costs around $600-$700. While OTS maps can get you started, they are generic and not optimized for your specific combination of parts. For a reliable 350+ HP build, invest in a custom tune from a reputable Cobb ProTuner, adding $300-$500 to the cost.

For the budget build, the Cobb Accessport plus a custom e-tune from a remote tuner (such as Delicious Tuning or Brentuning) is an excellent value. E-tunes are done via datalogging and email revisions, cutting out dyno time costs. Expect to pay $500-$700 for the device plus $300-$500 for the e-tune, for a total around $800-$1,200.

5. Supporting Parts and Consumables: $300 - $600

This category covers the small but essential components that ensure the system works reliably. Do not overlook these items, as they can cause headaches and boost leaks if neglected.

  • Oil feed and drain lines: High-quality stainless steel braided lines with proper fittings. Avoid rubber lines close to the turbo, as heat degrades them quickly. Budget $100-$150.
  • Vacuum lines and fittings: Silicone vacuum lines for the boost controller, wastegate, and blow-off valve. Use constant-tension clamps. Budget $40-$60.
  • Blow-off valve or bypass valve: A quality recirculating bypass valve (preferred for MAF-based systems) or a vent-to-atmosphere blow-off valve. Budget $50-$100.
  • Gaskets, bolts, and thread-locker: New manifold gaskets, turbo-to-downpipe gaskets, and high-quality fasteners. Budget $40-$60.
  • Coolant and oil: You will need new engine oil and coolant after the install, and potentially an oil cooler if your kit doesn't include one. Budget $50-$100.
  • Miscellaneous hardware: Wire loom, zip ties, heat wrap for the downpipe, and turbo blanket. These help manage heat and protect wiring and hoses. Budget $50-$80.

These supporting parts collectively ensure your system is airtight, oil-tight, and properly cooled. A single boost leak can cost you 20-50 horsepower and dangerously lean air-fuel ratios.

Beyond the Price Tag: Reliability and Supporting Mods

Reaching 350+ HP is one thing; keeping the engine alive for thousands of miles is another. The FA20 has known weak points that must be addressed to ensure longevity at this power level. Some of these are included in the budget above, but others may require additional spending or careful driving habits.

Oil Cooling and Management

The FA20's direct-injection design creates higher combustion temperatures, and the turbocharger adds significant heat to the oil system. Stock oil coolers are minimal. A quality oil cooler kit (such as Mishimoto or Setrab) with an oil thermostat should be considered essential if you plan to push the car hard on track or in hot weather. While not included in the base $5,000 budget, a $300-$400 oil cooler is a worthwhile investment for long-term reliability. If your budget is tight, at minimum install a high-quality oil pressure gauge and monitor oil temperature vigilantly.

Clutch Upgrades

The stock clutch is designed for the factory 200 HP and will likely begin slipping with 350+ HP, especially if you launch the car aggressively. A stage 2 or stage 3 clutch kit (e.g., Exedy Stage 2 or ACT Heavy Duty) will hold the power but adds $400-$600 to the total project cost. If you are on a strict $5,000 budget, accept that the clutch will be the first component to fail under hard use, and plan to replace it later. For daily driving with occasional pulls, the stock clutch may hold for a while if you are gentle with it, but it is a ticking time bomb.

Exhaust System

Your turbo kit will include a downpipe, but the rest of the exhaust system (mid-pipe and cat-back) is not included. A restrictive stock exhaust can choke power at higher RPM. A full 3-inch turbo-back exhaust system (downpipe plus cat-back) costs $800-$1,200. For the $5,000 budget, you can reuse the stock cat-back exhaust with a custom downpipe adapter, but you will likely lose some top-end power. Alternatively, a used aftermarket exhaust can be found for $300-$500. Consider this a secondary upgrade after the turbo system is running reliably.

For a deeper dive into FA20 engine reliability and common failure points under forced induction, visit Subispeed's tech articles which cover oiling mods and engine management best practices.

Installation: DIY vs Professional

The single biggest cost variable in this build is labor. The budget of $5,000 assumes you are doing the entire installation yourself in a home garage. A professional shop typically charges 15-25 hours of labor for a full turbo kit install, plus tuning time, easily adding $1,500-$3,000 to the total cost. If you lack mechanical experience, the project becomes more expensive, and you may need to adjust your power goal or budget.

If you are a first-time turbo installer, invest in a factory service manual (FSM) for your specific Subaru model and purchase specialized tools such as a torque wrench, a set of metric deep sockets, and a gasket scraper. Join forums like FT86 Club for detailed installation guides and troubleshooting threads. Expect the install to take a full weekend for a beginner, plus another day for addressing leaks and final checks. Do not rush the process, as a single loose bolt can cause an oil leak that leads to engine failure.

Tuning for 350+ HP

Tuning is the make-or-break step in this entire build. No matter how good your components are, a bad tune will destroy the engine. For a 350+ HP FA20 on 91 or 93 octane fuel, expect boost levels around 14-17 PSI with the correct turbo sizing. If you have access to E85, the same turbo can push 400+ HP with the right injectors and fuel pump, thanks to ethanol's higher octane and cooling properties.

During the tuning process, the tuner will dial in the ignition timing, air-fuel ratios, and boost control to deliver smooth power delivery without knock. On a conservative street tune, you will target air-fuel ratios of around 11.5:1 under full boost for gasoline, with ignition timing advanced carefully until knock is detected and then retarded slightly for a safety margin. A well-calibrated ECUtek or Cobb tune will also incorporate safety features such as boost cut, fuel cut, and high intake temperature protection.

It is common to make multiple pulls on a dyno or to spend several weeks refining an e-tune via street logs. Patience is essential. Expect final power to land between 330-370 wheel horsepower on a Dynojet or similar load-bearing dyno. Results will vary based on your component choice, fuel quality, and ambient conditions. Do not chase the last 10 horsepower at the expense of engine safety.

Real-World Expectations and Maintenance

A 350+ HP FA20 is a significantly different car to drive than a stock one. The turbo lag will be noticeable if you choose a larger turbo, and the car will demand higher quality fuel and more frequent oil changes. You should plan to change the engine oil every 3,000-4,000 miles with a high-quality synthetic 5W-30 or 5W-40, depending on your tuner's recommendation. Spark plugs should be replaced every 15,000-20,000 miles, as the increased cylinder pressure wears them faster. Inspect the wastegate actuator and boost control solenoid every oil change for carbon buildup or sticking.

Fuel economy will suffer significantly under boost, but with a conservative tune and gentle driving, you can still achieve highway fuel economy in the mid-20s MPG. Be prepared for the car to be louder, especially with a 3-inch exhaust, and for the cabin to smell more of fuel and oil during spirited driving. These are trade-offs for the performance gain, but the grin factor of a well-tuned turbo FA20 makes the effort worthwhile.

Conclusion

Building a 350+ HP FA20 engine on a $5,000 budget is a realistic and rewarding project for the dedicated DIY enthusiast. The key is allocating your funds strategically: invest in a quality turbo kit, a proper intercooler, and a comprehensive fuel system, while being disciplined about tuning and installation. Avoid the temptation to buy cheap off-brand components for the turbo or fuel system, as these are the parts where failure can cost you the entire engine.

By following the cost breakdown provided, you can achieve your power goal without breaking the bank, as long as you are patient, methodical, and willing to do the work yourself. The end result is a transformed vehicle that punches far above its weight class, delivering an exhilarating driving experience that rivals cars costing twice as much. Plan your build, buy quality parts, and enjoy the process of turning your FA20 into a forced-induction street weapon.