Why the GR86 is the Perfect Platform for Forced Induction

The Subaru BRZ / Toyota GR86 twins have carved out a legendary reputation for their nimble chassis, near-perfect weight distribution, and analog driving feel. Enthusiasts often praise the boxer engine’s low center of gravity and the car’s ability to dance through corners. However, one persistent complaint has been the powertrain’s modest output — the FA24D engine in the second-generation models delivers roughly 228 horsepower at the crank in stock form. While that is adequate for everyday fun, serious drivers hungry for straight-line muscle or track-day dominance quickly find themselves wanting more.

Enter the ProCharger Stage 2 Supercharger. This kit transforms the GR86’s character by delivering a massive, reliable power bump — from the stock ~320 horsepower (when measured at the wheels after a baseline tune) all the way to a verified 420 horsepower at the wheels. That’s a gain of over 100 wheel horsepower, achieved without the complexity and heat-soak issues often associated with turbocharging. In this expanded guide, we cover every aspect of the ProCharger Stage 2 system: engineering, installation, tuning, supporting modifications, and real-world performance numbers.

The Engineering Behind the ProCharger Stage 2

ProCharger has been a staple in the forced-induction market for decades, known for their self-contained, oil-fed centrifugal superchargers. Unlike twin-screw or roots-type blowers that pack air instantly at low RPM, a centrifugal supercharger builds boost progressively — much like a small turbocharger but driven by the engine’s crankshaft rather than exhaust gases. This design has distinct advantages for a boxer engine, where space is tight and thermal management is critical.

Centrifugal vs. Twin-Screw vs. Roots

  • Centrifugal (ProCharger): Linear power delivery, excellent efficiency at high RPM, minimal parasitic loss under light throttle. Boost climbs with engine speed, making it ideal for a high-revving engine like the FA24.
  • Twin-Screw: Instant, low-end torque but can create heat soak and require stronger internals. More stressful on the drivetrain for daily driving.
  • Roots (Eaton TVS): Good low-RPM grunt but heavier and less efficient at high RPM. Often used in muscle cars, not as suited for a rev-happy sports coupe.

The ProCharger Stage 2 uses a P-1X or D-1X head unit (depending on the kit version) with a high-efficiency billet impeller. The self-contained oiling system means no tapping into the engine’s oil supply — a huge plus for warranty-conscious owners and DIY installers.

Stage 2 Kit Contents

  • Centrifugal supercharger head unit (P-1X/D-1X)
  • Cast aluminum mounting bracket with CNC-machined components
  • High-flow air intake with large conical filter
  • Intercooler system (air-to-air or air-to-water, depending on generation)
  • Cast aluminum discharge pipe / charge piping
  • Drive belt system with heavy-duty tensioner
  • Fuel injectors (typically 725cc or 1050cc for E85 compatibility)
  • ECU calibration via Cobb AccessPort or ProCharger-supplied tune
  • Complete hardware kit and installation instructions

Each component is engineered to drop in with minimal cutting or drilling, preserving the factory appearance and resale value.

From 320 to 420 Wheel Horsepower: The Numbers

Before diving into the power increase, it is important to clarify the baseline. The stock FA24 engine on the GR86/BRZ produces about 228 hp at the crank, but most chassis dynamometers register around 190–200 wheel horsepower in bone-stock trim. The “320 HP” figure in many marketing materials refers to a Stage 1 ProCharger kit (without intercooler, running conservative boost). Stage 2 adds the intercooler and higher boost levels, bringing the car to a verified 420 wheel horsepower on 93 octane pump gas.

Here are the typical dyno results compiled from independent tuning shops and ProCharger’s own R&D:

  • Stock GR86 (FA24): 195–205 whp / 165–175 lb-ft torque
  • Stage 1 ProCharger (7 psi, no intercooler): 310–330 whp / 250–270 lb-ft torque
  • Stage 2 ProCharger (10 psi, with intercooler): 400–420 whp / 330–350 lb-ft torque
  • Stage 2 + E85 fuel (12 psi): 450+ whp / 380+ lb-ft torque

The power curve is remarkably smooth. Peak torque arrives around 5,500–6,000 RPM, but the car pulls hard all the way to redline. On the street, the difference is night and day — the GR86 goes from “peppy” to “blistering.” 0–60 mph times drop from the stock ~5.6 seconds to under 4.0 seconds with a good launch, putting the car in the same league as far more expensive exotics.

Supporting Modifications for Reliability

420 wheel horsepower is a significant jump for a factory engine. While the FA24 has strong cylinder walls and a forged crank, the pistons and rods are cast. Most owners find 400–450 whp to be safe with proper tuning and fuel. However, to fully support the Stage 2 kit, ProCharger and experienced tuners recommend the following upgrades:

  • Fuel system: Upgrade to 1050cc injectors and a larger fuel pump (AEM or DW) for E85. On 93 octane, 725cc injectors are sufficient.
  • Oil cooling: The boxer engine runs hot under sustained boost. An oil cooler (Setrab or similar) with a thermostatic sandwich plate is highly recommended for track days.
  • Clutch: The stock clutch will slip at 400+ whp. A Stage 2 or Stage 3 clutch (Exedy, ACT, or South Bend) is essential.
  • Exhaust: A 3-inch catless or high-flow downpipe and a catback exhaust reduce backpressure and help spool the supercharger more efficiently (though it’s still supercharged, not turbo).
  • Cooling system: A larger radiator and perhaps a water-methanol injection kit for track use can prevent heat soak on long sessions.

Installation: What to Expect

One of the ProCharger Stage 2’s biggest selling points is the installation ease. The kit is designed to mount using existing bolt holes on the front of the FA24 engine, requiring no drilling or welding for the bracket. Most experienced DIY mechanics can complete the job in a weekend (12–18 hours). A professional shop will take 8–12 hours.

Step-by-Step Overview

  1. Fuel system prep: Remove the intake manifold, replace the fuel injectors, and swap the fuel pump. This is the most labor-intensive part.
  2. Remove stock intake: The factory airbox and intake snorkel come out to make room for the supercharger inlet and filter.
  3. Mount the bracket: Bolt the ProCharger mounting bracket to the front of the engine, using the alternator and water pump bolt holes. Apply Loctite to all fasteners.
  4. Install the head unit: Secure the supercharger to the bracket, attach the drive belt, and tension according to the manual. The belt path is straightforward: crankshaft pulley to supercharger pulley, with a spring-loaded tensioner.
  5. Intercooler and piping: The intercooler core mounts in front of the radiator (or behind the bumper, depending on the kit version). Crosscheck the charge pipes to ensure no rubbing against the frame rails or hood.
  6. Connect oil lines: The self-contained oil system comes pre-filled. Two hoses run from the head unit to the oil cooler (if included) and back. No engine oil modification required.
  7. ECU calibration: Flash the provided ProCharger tune (via Cobb AccessPort) or have a professional tuner custom-calibrate the car on a dyno. For best results, dyno tuning is recommended.
  8. Final checks: Inspect all clamps, hoses, and electrical connections. Start the engine, check for oil leaks, and let the supercharger oil circulate. Road test gently, then gradually increase boost.

Note: The ProCharger kit includes a detailed step-by-step manual with torque specs. Do not skip the initial oil fill procedure — the head unit must be primed before first start-up. For a visual guide, refer to ProCharger’s official installation overview.

Tuning: The Key to Safe Power

No forced induction kit is complete without a proper tune. The ProCharger Stage 2 ships with a base calibration for 93 octane fuel, optimized for the injectors and boost level. However, every car is different. Differences in elevation, fuel quality, and engine health can cause detonation or knock. A custom dyno tune from a reputable tuner (like Delicious Tuning, Visconti Tuning, or CSG) will maximize power and safety.

For those who plan to run E85, the tune must be adjusted for the higher ethanol content and higher fuel flow. E85 provides excellent knock resistance, allowing boost to be safely raised to 12–13 psi, yielding 450+ whp. That setup requires an upgraded clutch and likely stronger axles if drag racing. Many owners report 60–80 more horsepower just from switching to E85 with a retune.

Always monitor fuel trims, intake air temperatures, and knock counts during the first few pulls. An aftermarket wideband O2 sensor and a boost gauge are highly recommended.

Real-World Driving Impressions

When a supercharged GR86 hits the road, the transformation is immediate. The engine retains its smooth, linear response below 3,500 RPM — you can still crawl in traffic without any bucking or surging. Once you cross 4,000 RPM, the boost builds steadily, and the car surges forward with a deep, mechanical wail. The centrifugal supercharger’s whine is less pronounced than a roots blower but still audible through the intake. It adds character without being tiresome.

On the track, the extra power pushes the GR86 into a new bracket. You will easily pull on M2s and Mustang GTs in the straights. Braking upgrades become essential: the stock brakes fade quickly with the additional speed. A big brake kit, along with stickier tires (200TW or 100TW), transforms the car into a track monster. The supercharged GR86 is no longer just a corner carver — it is a legitimate supercar hunter.

For daily driving, the car remains docile. Fuel economy takes a hit (expect 18–20 mpg combined), but the smile per gallon ratio is off the charts. The ProCharger Stage 2 is CARB-approved (EO D-669-39), meaning it is 50-state legal, which relieves emissions inspection worries.

Common Pitfalls and How to Avoid Them

  • Overheating on track: The biggest issue with any supercharged FA24 is heat. The boxer engine’s cylinder heads are close together, and the intercooler adds heat load to the radiator. Solution: add an oil cooler, consider a larger radiator, and install hood vents to release hot air.
  • Belt slip: Under heavy boost, the supercharger pulley can cause belt slip if the tensioner is not properly adjusted. ProCharger includes a heavy-duty Gates belt; ensure correct tension after 500 miles of break-in.
  • Fuel pump failure: Stock fuel pumps are not designed for the high demands of 400+ whp. If you hear the pump whining loudly, upgrade to a DW300c or AEM pump before it fails.
  • Clutch slip: The stock clutch will start slipping as soon as torque exceeds 300 lb-ft. Do not waste the money on a tune only to have the clutch give out in a week. Budget for a clutch upgrade.

Comparing ProCharger Stage 2 vs. Other Boost Options

The GR86/BRZ market is flooded with forced induction kits. Here is how the ProCharger Stage 2 stacks up against the competition:

  • Harrop TVS1740 (Eaton TVS): Positive displacement supercharger, instantaneous low-end torque, but harder to make over 400 whp without intercooler modifications. More expensive. Heat soak can be an issue.
  • JRZ (Jackson Racing) C38 Centrifugal: Similar design to ProCharger but with Rotrex head units. Slightly lower boost levels out of the box. Excellent street manners. ProCharger offers easier scalability with pulley changes.
  • Full-Race / PTuning Turbo Kits: Turbocharging offers higher top-end potential (500+ whp) but requires more plumbing, more heat management, and significantly more tuning effort. Lag can be noticeable. Turbo kits are often not CARB-approved.

For most owners who want a straightforward, reliable, CARB-legal 400 whp, the ProCharger Stage 2 is the sweet spot. It requires fewer modifications than a turbo kit and provides more linear power than a positive displacement blower. Check out FT86 Club’s community review for first-hand owner experiences.

Cost Breakdown and Value

The ProCharger Stage 2 kit retails for approximately $5,200–$5,800 depending on the retailer and included options (with or without fuel injectors, with or without an included tune). Installation at a shop will add $1,200–$2,000. A custom dyno tune adds $500–$1,000. If you add supporting mods (clutch, oil cooler, exhaust), budget an additional $2,500–$4,000. Total cost for a turnkey 420 whp GR86 is around $10,000–$13,000.

Is it worth it? Consider that a 420 whp GR86 with a proper suspension setup will outperform cars costing three times as much. The chassis is phenomenal, and this powertrain upgrade unlocks its full potential. For enthusiasts who plan to keep the car for several years, the ProCharger Stage 2 delivers an unmatched dollar-per-horsepower ratio.

Final Thoughts

The ProCharger Stage 2 Supercharger for the GR86 is not just a power adder — it is a transformation. It takes a wonderful sports car and injects it with muscle, while retaining the refined driving dynamics that made the GR86 famous. The jump from 320 whp to 420 whp is dramatic, yet the car remains daily-drivable and reliable when properly set up. With CARB approval, professional installation guides, and a strong aftermarket ecosystem, it is the go-to solution for owners who refuse to settle for stock.

If you are considering taking the plunge, connect with the community at GR86.org’s forced induction forum or browse ProCharger’s official site for the latest pricing and kit updates. Your GR86 will thank you.