BMW S55 6870 Single Turbo Kit
Turbo Pictured is a Precision (You can choose between Pulsar, Precision and Turbosmart)
Proven technology. Guaranteed fitment. Race-tested performance.
The BigBoost S55 6870 Single Turbo Kit provides a complete full-frame turbo solution for drivers pursuing serious horsepower, strong top-end airflow, and wanting to make BMW engines sound great again!
Every component was developed around proper fitment, thermal management, exhaust flow, durability, and serviceability. The result is a complete single-turbo platform suitable for high-powered street cars, drag builds, roll-racing applications, and dedicated race vehicles.
The 6870 turbocharger offers a strong balance between response and high-power capability.
Its larger compressor and turbine sections provide significantly more airflow than factory-frame and hybrid turbochargers. This allows the turbocharger to support higher power without operating near the limits of a restrictive factory-style turbine housing.
Compared with a hybrid turbo setup, the full-frame 6870 system provides:
• Increased compressor airflow
• Improved exhaust flow
• Lower exhaust restriction at high power levels
• Greater top-end power potential
• Improved efficiency at elevated boost
• More room for future engine and fuel-system upgrades
• Reduced dependence on excessive boost pressure to make power
The 6870 is designed for customers who want a turbo system that can continue supporting the build as power goals increase.
External Wastegate Boost Control
This kit uses an external wastegate system for precise and flexible boost control.
External wastegates manage exhaust flow independently from the turbocharger housing. This provides greater control over turbine speed and allows the system to bypass exhaust flow efficiently when the desired boost level is reached.
Twin-Scroll Manifold Design
The BigBoost manifold uses 1.5-inch runners for all six cylinders and a true twin-scroll configuration.
The divided manifold maintains exhaust pulse separation between the two cylinder groups. This helps preserve exhaust energy before it reaches the turbine and improves response from the larger full-frame turbocharger.
The manifold provides the flow capacity needed for high-output S55 applications without retaining the restrictive factory turbine housings used by hybrid turbo systems.
Engineered for Flow and Sound
Tested Under Harsh Conditions
We completed extensive in-house testing while measuring individual-cylinder exhaust gas temperatures and exhaust back pressure.
Under our tested configurations, the system produced approximately 1.11:1 to 1.12:1 exhaust back-pressure ratios at 28-30 PSI of IMAP.
These results demonstrate an efficient relationship between exhaust manifold pressure and intake boost pressure under the tested operating conditions.
Controlled exhaust back pressure helps:
• Reduce engine pumping losses
• Improve cylinder evacuation
• Manage exhaust temperature
• Support consistent high-RPM performance
• Reduce unnecessary stress at elevated power levels
Individual-cylinder EGT testing also allowed us to evaluate thermal distribution across all six cylinders instead of relying on a single exhaust temperature reading.
Modular and Upgradeable
The BigBoost S55 kit uses a modular full-frame design.
The turbocharger, wastegates, oil lines, coolant lines, charge-air components, and exhaust components can be serviced or upgraded individually.
This gives you more flexibility than a factory-frame hybrid setup, where the compressor, turbine housing, and internal wastegate system remain tied to the original turbocharger architecture.
As your build develops, you can change boost-control components, exhaust routing, or turbocharger specifications without replacing the entire system.
OEM+ Components and Fitment
The kit includes properly selected oil lines, coolant lines, fittings, charge-air components, clamps, and mounting hardware.
The Exhaust stainless steel Y-pipe has been manufactured utilizing casting which allows us to maximize internal area and eliminating boundary layer losses in this transition. Aeroquip hoses, SmartSeal clamps, Oetiker clamps, and constant-pressure clamps provide secure connections throughout the oil, coolant, and charge-air systems.
Kit Includes:
• Twin-scroll turbo manifold with 1.5-inch runners for all six cylinders
• 6870 full-frame turbocharger of choice
• External wastegate (Pulsar Precision or Turbosmart based on turbo choice)
• Wastegate Dump Tube
• Four-ply silicone hoses
• TIG-welded 304 stainless steel Y-pipe
• V-band clamp
• Silicone coolant hoses
• 2.5-inch boost pipe
• 4" Turbo Guard
• Stainless steel braided AN oil feed line
• Stainless steel turbo oil feed fitting
• Turbo oil drain coupler
• Silicone oil drain hose
• SmartSeal stainless steel hose clamps
• Oetiker hose clamps for Coolant and Oil Drain lines
Why Choose the BigBoost S55 6870 Kit?
The BigBoost S55 6870 External Wastegate Kit combines full-frame turbo performance, true twin-scroll exhaust flow, and flexible boost control.
You get:
• High horsepower potential
• Strong top-end airflow
• True twin-scroll pulse separation
• Precise external wastegate control
• Interchangeable wastegate spring options
• Compatibility with advanced boost controllers
• Efficient back-pressure levels under tested conditions
• Modular and serviceable components
• OEM+ fitment and hardware quality
• A system designed for continued upgrades
This is a complete S55 single-turbo platform for customers who want serious power, precise boost control, and the flexibility to adapt the system as their build progresses.