The Subaru BRZ and its Toyota GR86 twin have captured the hearts of driving enthusiasts worldwide with their lightweight chassis, sharp handling, and naturally aspirated FA24 engine. While the 2.4-liter flat-four delivers a satisfying 228 horsepower from the factory, many owners inevitably crave more grunt. The HKS Supercharger Kit for the FA24 engine offers a proven, reliable path to 50-plus wheel horsepower gains without sacrificing the car’s daily drivability or longevity. This article takes an in-depth look at what this kit entails, how it transforms the driving experience, and what you need to know before installing it on your BRZ.

Understanding the BRZ FA24 Engine: A Perfect Foundation for Forced Induction

The FA24 engine, introduced in the second-generation Subaru BRZ (2022+) and the Toyota GR86, is a 2.4-liter naturally aspirated boxer-four. It replaced the previous FA20 with a larger displacement, lower compression ratio (10.5:1 vs. 12.5:1), and a more robust bottom end. These changes make the FA24 significantly more receptive to forced induction than its predecessor.

Key Design Attributes of the FA24

  • Larger displacement (2,387 cc) provides a stronger torque curve and better response when bolting on a supercharger.
  • Forged connecting rods from the factory – a major upgrade over the FA20’s powdered-metal rods – increase reliability under boost.
  • Lower compression ratio reduces the risk of detonation under forced induction, allowing for safer power levels on pump gas.
  • Dual injection system (port and direct) enables better fuel atomization and helps keep intake valves clean, crucial for long-term supercharger use.

These engineering choices mean the FA24 can handle a well-designed supercharger kit without immediate internal modifications. The engine’s inherent strength, combined with modern engine management, gives tuners a wide safety margin when extracting additional horsepower.

The HKS Supercharger Kit: Engineering Excellence for the FA24

HKS has been a leader in forced induction for Japanese sports cars for decades. Their supercharger kit for the BRZ/GR86 FA24 is a complete, bolt-on system that uses a positive-displacement (Lysholm-type) supercharger. Unlike centrifugal superchargers that build boost with RPM, the HKS unit delivers immediate, linear boost from low RPM, mimicking the feel of a larger-displacement naturally aspirated engine but with far more torque.

Kit Components and Highlights

  • Twin-screw supercharger unit (similar to the popular HKS GT2 Supercharger platform) with integrated bypass valve for smooth off-boost cruising.
  • Dual-core air-to-air intercooler – maintains low intake air temperatures, critical for preventing detonation and ensuring consistent power.
  • High-flow intake system with a large conical air filter and streamlined ducting.
  • Engine management module (piggyback or reflash) – HKS provides a calibrated ECU solution that optimizes fueling and ignition timing for the increased airflow. Many kits are CARB-compliant (or at least emissions-legal in developed markets), though owners should verify their local regulations.
  • Complete hardware kit including brackets, hoses, belts, and pulleys – no custom fabrication required.

The system is designed to produce approximately 7–8 psi of boost on a stock engine, yielding 50–60 wheel horsepower gains. With supporting modifications (like a high-flow fuel system and professional tuning), power output can increase further, but the standard kit delivers a reliable daily-driver boost.

Installation: A Weekend Project for the Skilled Enthusiast

Installing the HKS Supercharger Kit is a moderate-difficulty job that most mechanically inclined owners can complete in a long weekend with basic hand tools and a lift or jack stands. The kit includes a detailed instruction manual, and many online resources provide step-by-step guidance.

Installation Overview

  1. Remove the factory intake manifold, airbox, and associated ducting. This provides access to the engine’s intake ports.
  2. Install the supercharger bracket and mount the supercharger unit. The bracket attaches to the engine block and is designed to provide a rigid mounting point without interfering with accessories.
  3. Route the intercooler and charge pipes. The front-mount intercooler fits behind the factory bumper beam, requiring minimal trimming on the GR86/BRZ.
  4. Install the new drive belt. The supercharger is driven by a dedicated belt from the crankshaft pulley; the kit includes an appropriately sized belt and tensioner.
  5. Connect the ECU module and wiring harness. Most kits plug into the factory OBD-II port or directly into the ECU, with instructions for wire tapping where necessary. Professional installation is recommended if you are not comfortable with electrical work.
  6. Reassemble the intake system, check all connections, and purge the coolant system if the intercooler is water-cooled. (The HKS unit is air-to-air, so no coolant lines to worry about.)
  7. Perform an initial start-up and check for leaks. Let the engine idle and reach operating temperature, then verify no boost leaks from the charge pipes or intercooler.

After installation, the car must be professionally tuned or run with the supplied HKS calibration. The kit’s plug-and-play tuning is conservative and safe, but a custom tune on a dyno can extract additional power and tailor the driving experience to your fuel quality and climate.

Performance Gains: What to Expect on the Dyno and on the Road

Once installed and tuned, the HKS-supercharged FA24 transforms from a peppy naturally aspirated engine into a genuinely quick powerplant. Dyno results from independent shops consistently show gains of 50–60 horsepower at the wheels on 93 octane fuel, with peak torque climbing from around 180 lb-ft to over 210 lb-ft. The power curve is remarkably flat, with strong pull from 3,000 rpm all the way to redline.

Drivability and Throttle Response

Unlike a large turbocharger that can introduce lag, the HKS supercharger provides immediate boost response. The linear nature of the twin-screw unit means the engine feels like a high-displacement naturally aspirated V6, with no sudden surge of power that could unsettle the chassis on corner exit. This predictable power delivery makes the car easier to drive at the limit on track or on canyon roads.

For daily commuting, the supercharged BRZ feels effortless. Merging onto highways requires only a light throttle application, and overtaking slow traffic no longer demands a downshift to fourth gear. The car retains its factory low-RPM manners – the bypass valve opens during light load, minimizing parasitic loss and keeping fuel economy acceptable.

Supporting Modifications for Maximum Reliability

While the HKS kit is designed to work with an otherwise stock BRZ, certain supporting upgrades are wise investments to ensure long-term durability and performance consistency.

Fuel System Upgrades

The FA24’s direct injection can handle the additional fuel demand from moderate boost levels, but higher ethanol content (E85) or aggressive tuning will require upgraded fuel pumps and potentially larger injectors. Many tuners recommend an aftermarket high-pressure fuel pump (HPFP) to prevent fuel pressure drop at high RPM. HKS themselves offer optional fuel system components for their kit.

Oil Cooling

Forced induction increases engine heat load, especially during extended track sessions. Installing a larger oil cooler (such as the Mishimoto or Perrin units) helps maintain safe oil temperatures, which is critical for preventing oil breakdown and bearing wear. The supercharger itself also benefits from cooler oil, as it shares the engine’s oil system in most configurations.

Clutch Upgrades

The factory clutch is adequate for the stock power level, but the added torque from the supercharger may cause it to slip under hard acceleration or during aggressive launches. A stage 1 or stage 2 clutch kit from ACT or Exedy can handle the extra 50+ horsepower without making the pedal too heavy for daily driving.

Long-Term Reliability and Maintenance

One of the most common concerns about supercharging a modern sports car is the impact on engine longevity. The HKS kit, when properly installed and tuned, has a strong reliability track record. The FA24 engine’s forged rods and lower compression ratio provide a robust foundation. The key to longevity is maintaining the supercharger and engine fluids meticulously.

Maintenance Tips for Your Supercharged BRZ

  • Change engine oil every 3,000–5,000 miles using a high-quality full synthetic 5W-30 (or 0W-40) meeting ILSAC GF-6/ACEA A3/B4 standards. More frequent oil changes help remove the additional heat and contaminants from boost operation.
  • Inspect the supercharger drive belt at every oil change. A loose or worn belt can cause boost loss or damage the supercharger pulley.
  • Clean the intercooler core periodically, especially if you drive on dusty roads or in areas with heavy pollen. A clogged intercooler reduces cooling efficiency and power.
  • Monitor boost levels with an accurate boost gauge. A sudden drop in boost may indicate a leak; a gradual increase could mean the bypass valve is sticking.
  • Use fuel from a reputable station with an octane rating of 93 (or 91 minimum) to prevent detonation. If you plan to track the car, consider blending E85 for additional knock resistance (requires supporting tune and fuel system).

The supercharger itself is a sealed unit with its own internal oil supply (most HKS twin-screw units are oil-fed from the engine, but check your specific kit). If your kit has a separate oil reservoir, inspect the level annually and replace the oil every 30,000 miles as recommended by HKS.

Comparing Supercharging to Turbocharging for the FA24

Both forced induction methods have their loyalists. Here’s how the HKS supercharger stacks up against a typical turbocharger kit for the BRZ/GR86.

Supercharger Pros

  • Instantaneous throttle response – no spool time; power is always on tap.
  • Linear power delivery – easier to control at the limit, more predictable for corner exit.
  • Lower exhaust gas temperatures – no added backpressure from a turbo, which can stress the engine under load.
  • Easier installation – no need to route turbo plumbing or fabricate downpipes; bolt-on kit fits in stock locations.

Turbocharger Pros

  • Higher peak power potential – turbo systems can easily exceed 300 wheel horsepower with larger injectors and fuel system.
  • Better fuel economy under light load – turbo cars can cruise with essentially no backpressure, but the supercharger’s parasitic drag is minimal at cruise thanks to the bypass valve.
  • More tuning flexibility – turbo setups allow you to match compressor size to your power goal, but this requires more fabrication expertise.

For 90% of enthusiasts who want a reliable upgrade that retains factory drivability, the HKS supercharger is the better choice. For those chasing max power numbers or building a dedicated track car, a turbo kit may be worth the added complexity. Many owners start with a supercharger and later switch to turbo if they outgrow the power.

Real-World Owner Experiences

Online forums and owner reviews consistently praise the HKS supercharger for its seamless integration and transformation of the BRZ/GR86. Common remarks include:

  • The car feels like it should have come from the factory with the kit – it never feels overwhelmed or out of sorts.
  • Reliability has been excellent even after 20,000+ miles of mixed driving, including track days.
  • Fuel economy drops only slightly (by about 2–3 mpg) when driven normally, but plummets during heavy boost use.
  • The kit installs cleanly under the hood, with no cutting of critical structural parts.

Some owners note that the included HKS ECU calibration is a good starting point, but a professional tune from a reputable shop like Delicious Tuning or MAPerformance can unlock more power and refine drivability. Tuning is especially important if you use higher octane fuel or live at altitude.

Conclusion

The HKS Supercharger Kit delivers exactly what BRZ FA24 owners seek: a significant, reliable horsepower increase without introducing the compromises typical of forced induction. With 50-plus wheel horsepower gains, immediate throttle response, and a comprehensive bolt-on design, it elevates the driving experience from enjoyable to genuinely exhilarating. When combined with sensible supporting modifications and proper maintenance, the supercharged FA24 remains a daily-usable, track-capable powerhouse that stays true to the BRZ’s lightweight, driver-focused ethos. For any enthusiast considering a power upgrade, the HKS Supercharger Kit deserves to be at the top of the list.