Scion FR-S Supercharger Build: 300HP Without Blowing Up

Why Your FR-S Needs Forced Induction

Every FR-S/BRZ owner knows the frustration: that boxer engine sounds great but delivers underwhelming performance. After reviving our 2013 Scion FR-S from near-death, we faced its core weakness – just 170 wheel horsepower after years of neglect. We set an ambitious goal: 300+ crank horsepower using a Jackson Racing supercharger, nitrous, and supporting mods while avoiding catastrophic failure. This guide reveals how we achieved 314 HP without grenading the engine.

Supercharger System Selection and Installation

Why Jackson Racing’s Road Trek Dominates

Unlike traditional centrifugal superchargers, the Road Trek uses a 9:1 gear-driven system spinning at 90,000 RPM. Its independent oiling system is critical – it runs specialized traction fluid (not engine oil) to survive extreme speeds. After analyzing dyno results from Unrivaled Tuning, we confirmed this design prevents oil starvation during high-G cornering, a common failure point with cheaper kits.

Step-by-Step Installation Insights

Sound Tube Delete: First, we removed the factory sound tube – a useless weight adder that pipes artificial engine noise into the cabin.
Precision Trimming: Using Jackson Racing’s laser-cut template, we trimmed AC compressor and alternator covers for belt clearance. Pro tip: Dremel slowly to avoid melting plastic.
Oil System Setup: The banjo fittings and oil cooler require careful routing. We reused a mystery bolt near the factory reservoir (saving $20 on hardware) – a clever hack Jackson Racing engineers endorsed.
Intercooler Challenges: Relocating the washer fluid reservoir was essential. The kit’s replacement unit mounts securely but requires transferring the original pump.

Critical Mistake Avoided: During mock-up, the intercooler piping interfered with the supercharger pulley. We trimmed 0.5" off the connector – measure twice, cut once.

Supporting Modifications: Beyond the Blower

Fuel System Upgrades

The factory 450cc injectors couldn’t support our power goal. We installed DeatschWerks 900cc injectors with plug-and-play pigtails. During testing, a grounding issue (caused by a missing bolt on the DI control unit) prevented startup. Always check grounding points after ECU swaps – this oversight cost us 3 hours of diagnostics.

ECU and Tuning Strategy

A Link ECU eliminated complex wiring. Key steps:

Installed a wideband O2 sensor for accurate air/fuel monitoring
Used a "base map" for initial startup
Partnered with Unrivaled Tuning for remote calibration
Tuner Danny emphasized: “Reduce timing before adding nitrous” – a non-negotiable for stock FA20 engines.

Exhaust and Aesthetics

The Remark quad-tip exhaust replaced restrictive factory piping. Its burnt titanium tips and refined acoustics avoid "fart can" drone. Pro tip: Loosely fit all components before final tightening to align tips perfectly with our Saibon carbon diffuser.

Nitrous Integration: Controlled Risk

Dry vs. Wet Kits Explained

We chose a dry nitrous system (nitrous only, no extra fuel) for simplicity. The nozzle injects N₂O pre-throttle body via a sandwich plate. Jet sizing is critical – too large, and you risk lean detonation. We started with a conservative 50-shot jet.

Safety Protocols

Hood closed during dyno pulls (containing potential explosions)
Nitrous line routed through the factory sound tube’s firewall passage
Progressive controller to prevent pressure spikes

Controversial Decision: Many claim nitrous is unsafe for FA20 engines. Our experience shows 50-shot on 91 octane is viable with pulled timing – but avoid sustained use.

Dyno Results and Reliability Verdict

Supercharger-Only Performance

On 91 octane, baseline dyno runs revealed:

190 WHP (degraded from factory 170 WHP)
235 WHP after base tuning
262 WHP (≈290 crank HP) with optimized timing – the safe limit on pump gas

Nitrous Activation

Adding a 50-shot nitrous jet yielded 280 WHP (314 crank HP). After 12+ dyno pulls and 500 street miles, the engine survived. However, Unrivaled Tuning warns: “FA20 rods fail around 350 WHP. This is the absolute ceiling for stock internals.”

Will Your FR-S Survive?

Based on our teardown and tuning data:
✅ Do:

Use traction fluid, not engine oil
Upgrade to 900cc+ injectors
Install an oil cooler
Limit nitrous to 50-shot
❌ Don’t:
Skip ECU tuning
Use ethanol blends without fuel system upgrades
Run nitrous without wideband monitoring

Toolbox and Pro Recommendations

Immediate Checklist:
- Verify supercharger oil weep hole pre-startup
- Ground DI control unit properly
- Pressure-test fuel lines post-injector install
Expert-Approved Gear:
- Link ECU: Plug-and-play tuning ($1,200)
- AEM Wideband: Real-time AFR tracking ($200)
- Nitrous Outlet Safe Shot: Prevents solenoid leaks ($159)

Final Thoughts

We achieved 314 HP by respecting the FA20’s limits – proving forced induction is viable with meticulous execution. As Jackson Racing’s Oscar emphasized: “Low boost, conservative timing, and quality fuel are non-negotiable.” For those attempting this build, invest in professional tuning; it’s the barrier between triumph and a $6,000 engine replacement.

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