Overview: Converting the S55 to a Single Turbo
Upgrading a BMW F80 or F82 S55 from the factory twin turbos to a single turbo setup is one of the most significant performance changes you can make.
This conversion replaces the stock system with a high-flow single turbo configuration, allowing for increased airflow, higher boost levels, and substantially more power.
The 4N Motorsport kit is designed specifically for this platform, making it one of the most effective solutions for high-performance builds.
What Comes in a 4N Motorsport Single Turbo Kit
A complete kit is designed to replace and reroute the entire turbo system.
Typical Components Include:
- Bottom-mount turbo manifold
- Single turbocharger
- External wastegate
- Downpipe
- Oil and coolant lines
- Charge piping
- Intake components
- Hardware and fittings
Each part works together to support higher airflow and boost efficiency compared to the factory twin turbo setup.
Required Supporting Modifications
Before installation, supporting mods should already be planned or installed.
Essential Upgrades:
- Upgraded intercooler
- High-flow intake system
- Performance exhaust system
- Fuel system upgrades (port injection recommended)
- Custom ECU tuning
Skipping these components will limit performance and can lead to reliability issues.
Step-by-Step Install Overview
This is a simplified breakdown of the install process. Actual installation requires advanced mechanical experience.
1. Remove Factory Twin Turbos
- Remove intake, heat shielding, and factory turbo assemblies
- Disconnect oil and coolant lines
- Clear space for new system
2. Install Single Turbo Manifold
- Mount bottom-mount manifold to engine
- Ensure proper fitment and clearance
3. Mount Turbocharger & Wastegate
- Install turbo onto manifold
- Attach external wastegate
- Align for proper routing
4. Install Oil & Coolant Lines
- Connect turbo oil feed and return lines
- Route coolant lines if applicable
- Check for leaks and proper sealing
5. Install Downpipe & Exhaust Routing
- Connect custom downpipe to turbo
- Integrate with existing exhaust system
6. Install Charge Piping & Intake
- Route charge pipes from turbo to intercooler
- Install intake system
- Ensure all connections are sealed
7. Integrate Fueling System
- Install port injection system (if applicable)
- Connect fuel controller
- Verify fuel delivery system
8. Final Checks & Tuning
- Inspect all connections
- Prime oil system
- Perform custom ECU tuning
Power Expectations
With the proper setup and tuning, the S55 platform can achieve:
- 600–700 HP (moderate builds)
- 700–800+ HP (fully built setups)
The key advantage of the single turbo system is its ability to maintain strong power at higher RPMs, unlike stock turbos which taper off.
Driving Characteristics After Installation
Switching to a single turbo changes how the car delivers power.
Key Differences:
- Later boost onset compared to stock
- Stronger mid-range and top-end pull
- More aggressive acceleration curve
This setup is designed for performance-focused driving, not just daily comfort.
Common Mistakes to Avoid
- Skipping fueling upgrades
- Using low-quality components
- Improper installation
- Running the car without proper tuning
Each of these can lead to serious engine or performance issues.
Is This Upgrade Worth It?
A single turbo conversion is ideal for those who want:
- High horsepower potential
- Scalable performance upgrades
- A more aggressive driving experience
It’s not necessary for every build—but for serious enthusiasts, it’s one of the most effective upgrades available.
Final Thoughts
The BMW F80 and F82 S55 platform is capable of impressive performance—but a single turbo setup unlocks its full potential.
With the 4N Motorsport kit, you’re not just upgrading components—you’re building a system designed for real power, efficiency, and performance.
Done correctly, this conversion delivers a driving experience that goes far beyond what the factory setup can offer.