Choosing the Right Single Turbo Kit for Your S55
If you’re upgrading your BMW F80 or F82 S55 to a single turbo, two names come up constantly:
- 4N Motorsport single turbo kit
- Big Boost single turbo kit
Both are capable of serious power—but they’re built for different types of builds and drivers.
This guide breaks down exactly how they compare so you can choose the right setup.
Quick Comparison: 4N vs Big Boost
| Feature | 4N Motorsport | Big Boost |
|---|---|---|
| Power Potential | 700–900+ WHP | 650–850+ WHP |
| Turbo Options | Large-frame, race-focused | More customizable sizing |
| Spool Characteristics | Strong mid-top end | Faster spool (depending setup) |
| Build Style | Race-inspired, high-end | Street + performance balance |
| Price Range | $$$$ | $$$ |
| Best For | Maximum power builds | Balanced street/track builds |
4N Motorsport Single Turbo Kit (Deep Dive)
The 4N Motorsport kit is built with a strong focus on high horsepower and race-level performance.
What Makes It Stand Out
- Designed from racing experience and high-performance engineering
- Proven to support 700–900+ WHP builds with proper setup
- Optimized for top-end power and airflow
- High-quality manifolds and hardware
Performance Characteristics
- Strong top-end pull
- Aggressive power delivery
- Built for high boost levels
👉 This is the kit you choose when your goal is maximum power, not compromise
Big Boost Single Turbo Kit (Deep Dive)
Big Boost is known for building turbo kits that balance performance, drivability, and flexibility.
What Makes It Different
- Multiple turbo sizing options (more customization)
- Designed for both street and high-power builds
- Typically easier to tailor to your exact goals
Performance Characteristics
- Faster spool (depending on turbo size)
- Smoother power delivery
- More street-friendly setups available
👉 This is ideal if you want strong power but still daily-drive your car comfortably
Power Potential: Which Makes More Power?
Both kits are capable—but the difference is in how they deliver it.
-
4N Motorsport:
- Built for pushing limits
- Commonly used in 700–900+ WHP builds
-
Big Boost:
- Still capable of big numbers
- More commonly seen in balanced 600–800 WHP setups
👉 If your goal is chasing numbers, 4N has the edge
Spool & Driving Feel
This is where things really separate.
4N Motorsport
- Slightly later spool
- Explosive mid-range and top-end
- More aggressive driving experience
Big Boost
- Quicker spool (with smaller turbo options)
- Smoother, more linear power
- Better for daily driving
👉 Big Boost wins for drivability
👉 4N wins for raw performance feel
Build Quality & Engineering
Both kits are high-quality—but built with different priorities.
-
4N Motorsport:
- Race-proven designs
- Focus on durability at extreme power levels
- High-end fabrication
-
Big Boost:
- Strong engineering with flexibility
- Designed for a wider range of builds
- Easier customization
Installation & Complexity
Both require:
- Full turbo system replacement
- Fueling upgrades (port injection recommended)
- Custom tuning
No matter which you choose:
👉 This is NOT a beginner install
Reliability Considerations
Reliability depends more on:
- Tuning quality
- Fueling setup
- Installation
Not just the kit itself.
That said:
- 4N is built for extreme power reliability
- Big Boost is built for balanced long-term use
Which One Should You Choose?
Choose 4N Motorsport if:
- You want 700–900+ HP
- You’re building a serious performance car
- You care about top-end power and racing performance
Choose Big Boost if:
- You want a fast, street-friendly setup
- You care about spool and drivability
- You want flexibility in turbo sizing
Final Verdict
There’s no “better” kit—only the right one for your goals.
- 4N Motorsport = Maximum power, aggressive performance
- Big Boost = Balanced power, better drivability
If your F80/F82 feels slow and you’re ready to take it to the next level, both of these kits can transform your S55—just in different ways.
FAQ
Q: What is the best single turbo kit for BMW S55?
A: 4N Motorsport and Big Boost are two of the most popular, each suited for different goals.
Q: How much horsepower can a single turbo S55 make?
A: 700–900+ WHP with proper fueling and tuning
Q: Is single turbo better than upgraded twins?
A: For high horsepower builds, yes—single turbo setups provide more airflow and higher power ceilings