The Subaru BRZ and the Quest for 300 Horsepower

The Subaru BRZ is a driver’s car in its purest form—lightweight, rear-wheel drive, and blessed with a low center of gravity. Its 2.0-liter FA20 boxer engine delivers around 200 horsepower stock, providing a balanced, naturally aspirated experience that excels on twisty roads. But many enthusiasts quickly crave more punch. Adding a turbocharger is the most effective way to gain substantial power while keeping the car’s essential character. The goal of 300 horsepower at the wheels is a sweet spot: enough to transform acceleration without overwhelming the chassis or requiring extensive drivetrain upgrades. The Cosworth Turbo Kit, engineered specifically for the BRZ, offers a proven path to this target. This article expands on everything you need to know—from component selection and installation to tuning and long-term reliability—to achieve 300 horsepower safely and sustainably.

Why 300 HP for the BRZ?

Before diving into the kit itself, it’s worth understanding why 300 whp is a popular benchmark. The BRZ’s factory engine and drivetrain can handle this power level with reasonable upgrades. Above 350 whp, the transmission becomes a weak link, and cooling demands increase significantly. At 300 whp, you get a power-to-weight ratio that rivals many modern sports cars without sacrificing the BRZ’s nuanced handling. It’s an exhilarating yet manageable upgrade for street and track use.

Cosworth Turbo Kit: A Deeper Look

Cosworth has a legendary motorsport pedigree, and their BRZ kit reflects that. It’s a complete, bolt-on system designed to integrate with the FA20’s unique boxer layout. The key advantage over generic turbo kits is that Cosworth has matched every component to work together, reducing guesswork and potential fitment issues. Let’s examine each piece in detail.

Turbocharger

The kit uses a Garrett GT2854R (or similar) ball-bearing turbocharger. Ball bearings reduce friction for faster spool compared to journal-bearing alternatives. This means boost comes on earlier—around 3000–3200 rpm—so the car remains responsive and fun to drive daily. The turbine housing is sized to produce approximately 8–10 psi of boost, which, combined with proper fueling, yields 300 whp on pump fuel (93 octane). Cosworth’s compressor map ensures good efficiency without excessive heat, which is critical for long engine life.

Intercooler and Charge Air System

Cosworth supplies a high-flow air-to-air intercooler with cast aluminum end tanks. It’s mounted in the front bumper area and ducted to receive ambient air directly. The kit includes mandrel-bent aluminum piping with silicone couplers and T-bolt clamps, minimizing pressure drop. Thermal efficiency is improved over a generic intercooler; this allows the engine to maintain consistent power even during sustained hard driving. The system also includes a blow-off valve (plumbed recirculating), which helps maintain idle stability and reduces turbo lag between shifts.

Cast Exhaust Manifold and Up-Pipe

The exhaust manifold is a key differentiator. Cosworth uses a cast stainless steel manifold (rather than tube-style), which is less prone to cracking under thermal cycles. It’s designed with equal-length runners to scavenge exhaust pulses efficiently, aiding spool and reducing exhaust gas temperature (EGT) spikes. The integrated up-pipe routes exhaust to the turbo with minimal bends. Heat shielding or ceramic coating is recommended but not always included—plan to wrap or coat these parts to keep engine bay temperatures down.

Fuel System Upgrades

To supply enough fuel for 300 whp, the kit includes higher-flow fuel injectors (typically 550cc or 600cc) and a larger fuel pump. The injectors are direct-replacement units that fit the FA20’s intake manifold. The fuel pump upgrade ensures sufficient flow under boost. Some tuners also recommend adding an uprated pressure regulator for finer control. Proper fueling is non-negotiable for safety—lean conditions under boost can destroy piston rings or melt electrodes.

Engine Management and Tuning

The kit comes with an ECU “reflash” or a standalone piggyback unit (often from ECUTek or Cobb Accessport). The Cosworth package includes base maps tailored to the hardware, but these should be considered starting points—not final calibrations. Every car is slightly different, and factors like fuel quality, altitude, and engine condition require professional calibration.

ECUTek vs. Cobb Accessport

Both are popular for BRZ tuning. ECUTek is often preferred by professional tuners for its advanced features (boost control, flex-fuel capability). Cobb Accessport offers simpler on-the-fly map switching and easy logging. Whichever you choose, the goal is the same: dial in air/fuel ratios, ignition timing, and boost pressure to achieve safe and strong power output.

Installation: Step-by-Step and Critical Tips

Installing a turbo kit is not a weekend project for a novice. Expect 20–30 hours of labor if you’re experienced; it’s wise to budget for a professional shop. Here’s a high-level sequence and pitfalls to avoid.

Pre-Installation Preparation

  • Gather all tools: torque wrenches, socket set, flathead and Phillips screwdrivers, wire crimpers, and heat gun.
  • Read the entire Cosworth instruction manual. Lay out all parts and verify nothing is missing.
  • Replace spark plugs (one step colder) and consider upgrading the oil cooler and radiator before installation—doing it later is more work.
  • Consider a clutch upgrade (e.g., ACT or Exedy stage 1) if your stock clutch shows signs of wear. 300 whp will kill a tired clutch quickly.

Removal of Stock Components

Remove the intake manifold, exhaust headers, front pipe, and intercooler ductwork. Drain coolant and engine oil. Disconnect the battery and remove the ECU for easy access. This is a good time to clean the engine bay and address any oil leaks.

Turbo and Manifold Installation

Install the Cosworth exhaust manifold with new gaskets. Torque all bolts to spec. Mount the turbocharger to the manifold with the included oil and coolant lines. The oil feed line should be tapped from the engine block; Cosworth provides the necessary adapter. The drain line must slope downward to gravity feed back to the oil pan—a kinked drain line will cause smoking seals. Use heat shield material around the turbo and manifold to protect wiring and hoses.

Intercooler and Piping

Mount the intercooler using the provided brackets. Route the charge pipes from the turbo to the intercooler and then to the throttle body. Trim plastic shrouding as needed for clearance. Ensure all couplers are tight. A boost leak test (using a tester and compressed air) at this stage saves headaches later.

Fuel System and ECU

Install the new fuel injectors and high-pressure fuel pump. Reconnect fuel lines and prime the system (key on, engine off) to check for leaks. Install the tuning device (Accessport or ECUTek cable) according to instructions. Upload the base map, but do not start the engine yet.

Final Checks and First Start

  • Double-check all bolts, clamps, and wiring connections.
  • Refill coolant and engine oil (use full synthetic 5W-30 or 0W-40 for turbo applications).
  • Disconnect the ignition coil connectors and crank the engine for a few seconds to build oil pressure before first start.
  • Start the engine. Listen for abnormal noises. Check for smoke, fluid leaks, and proper fan operation.
  • Let the engine idle until it reaches operating temperature, then inspect again.

Tuning for Safe 300 HP

This is where the magic happens—and where many mistakes occur. Never boost the car on the base map without a professional tuner reviewing it. Here’s what the tuning process involves.

The Tuning Session

A skilled tuner will use a dynamometer (dyno) to load the engine while monitoring wideband oxygen sensors, knock sensors, fuel pressure, and boost pressure. They will adjust the following maps:

  • Air/Fuel Ratio (AFR): Target about 11.5:1 under full boost for gasoline (richer for intercooled setups). Leaner than 12.0:1 risks detonation.
  • Ignition Timing: Find the boundary where knock occurs and back off a few degrees for safety. More boost usually requires less timing.
  • Boost Control: Set the wastegate duty cycle to achieve the desired boost curve (e.g., 9 psi tapering to 7 psi at redline to protect the engine).
  • Fuel Trim Adjustments: Fine-tune individual cylinder corrections if using ECUTek.

A well-tuned BRZ Turbo should produce a smooth, linear torque curve. Peak torque around 3,500–4,500 rpm and power holding until 7,000 rpm is typical.

Data Logging

After the dyno session, do road logs to verify performance under real-world load. Check for knock correction, fuel pressure drop, and intake air temperatures. If IATs exceed 140°F, consider upgrading the intercooler or adding water-methanol injection.

Supporting Modifications for Safety and Reliability

Power is nothing without control. These upgrades are strongly recommended when targeting 300 HP.

Cooling System

The FA20 is known for high cylinder head temperatures under load. A larger aluminum radiator (Koyorad or Mishimoto), a lower-temperature thermostat, and an oil cooler (Setrab or Mishimoto) will keep engine temps in check during spirited driving. The stock cooling system can overheat on track days with a turbo.

Drivetrain

The BRZ’s transmission (especially the manual) is a known weak point. At 300 HP, it will hold up if driven sympathetically, but repeated drag launches or clutch drops can break gears. Consider a transmission swap to a stronger unit (e.g., STi 6-speed) if you plan to track aggressively. An upgraded clutch is mandatory—a stage 2 organic clutch from ACT or Exedy handles the torque without making daily driving miserable.

Brakes and Suspension

Higher speeds require better stopping power. Replace brake pads with track-rated compounds (e.g., Ferodo DS2500), upgrade to stainless steel brake lines, and use high-temp brake fluid (Motul RBF600). For suspension, a set of coilovers (Ohlins or KW) will control the added weight transfer and keep the tires planted.

Wheels and Tires

Factory tires will struggle with 300 HP. Use 200-wear-rated summer tires (Michelin Pilot Sport 4S or Yokohama Advan A052) in 245/40R17 or 255/35R18 for better grip. Wider wheels (9-9.5 inches) provide more contact patch.

Long-Term Maintenance and Common Issues

A turbocharged BRZ demands more attention than a stock one.

  • Oil Changes: Every 3,000–4,000 miles with high-quality synthetic oil. The turbo places more heat stress on oil.
  • Spark Plugs: Replace every 20,000 miles (one step colder). Fouled plugs can cause misfires under boost.
  • Check for Boost Leaks: Annual smoke test or listening for whistling noises.
  • Turbo Wastegate: Ensure the actuator rod moves freely; sticking can cause overboost.
  • Serpentine Belt: Upgrade to a Kevlar belt (stronger) as the stock belt can slip with added pulley resistance.

Common issues include blown intercooler couplers (upgrade to T-bolt clamps), cracked exhaust manifold if not properly supported, and oil leaks from the turbo oil return line. Address these promptly to prevent cascading failures.

External Resources

For further reading and official specifications, refer to the following:

Conclusion

The Cosworth Turbo Kit is one of the most complete and reliable ways to bring the Subaru BRZ to 300 horsepower. By understanding each component, following a precise installation, and investing in professional tuning and supporting upgrades, you can create a car that is both faster and still dependable for daily driving or track days. The key is patience—do not cut corners on cooling, fuel system, or clutch. With the right approach, your turbocharged BRZ will put a smile on your face every time the boost hits.