BMW S55 BorgWarner EFR Single Turbo Kit
Proven technology. Guaranteed fitment. Race-tested performance.
The BigBoost S55 EFR Single Turbo Kit provides a complete, purpose-built solution for drivers who want the power potential of a full-frame single turbo without the added complexity commonly associated with external-wastegate systems.
Every component was developed around proper fitment, thermal management, exhaust flow, serviceability, and OEM-quality installation. The result is a clean and responsive single-turbo system suitable for high-performance street cars, track builds, and dedicated race vehicles.
BorgWarner EFR Performance
Choose between the BorgWarner EFR 8474 or 9280 based on your desired balance of response and top-end power.
EFR stands for Engineered for Racing. These turbochargers combine a lightweight Gamma-Ti turbine wheel, dual ceramic ball bearings, and BorgWarner Extended Tip compressor technology. The low-inertia turbine assembly supports fast boost response, while the compressor design provides strong airflow and high-boost capability for its size.
This gives the S55 a broad and usable powerband instead of building a system focused only on peak horsepower.
Simplified Electronic Wastegate Control
The EFR configuration is ideal for customers who want a simple and clean single-turbo installation.
Our EWG mounting kit allows the system to operate with an electronic wastegate actuator through a dedicated bracket and linkage system.
This eliminates the need for:
• Separate external wastegates
• Open wastegate dump tubes
• External boost controllers
• Additional wastegate vacuum lines
• Complex boost-control plumbing
You get the benefits of a full-frame single turbo with a cleaner engine bay and fewer components to install, adjust, or maintain.
Twin-Scroll Manifold Design
The BigBoost manifold uses 1.5-inch runners for all six cylinders and a true twin-scroll configuration.
The divided design maintains exhaust pulse separation between the two cylinder groups. This helps preserve exhaust energy at the turbine and supports stronger response from the larger full-frame turbocharger.
The manifold provides the exhaust flow capacity needed for high-power S55 applications without relying on the restrictive factory turbine housings used by hybrid turbochargers.
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 kit produced approximately 1.11:1 to 1.12:1 exhaust back-pressure ratios.
These results demonstrate an efficient relationship between exhaust manifold pressure and intake boost pressure under the tested operating conditions. Controlled back pressure helps reduce pumping losses, manage exhaust temperature, and allow the engine to operate more efficiently at higher power levels.
Testing individual-cylinder EGT also allowed us to evaluate how evenly the manifold distributes thermal load across the engine instead of relying only on one temperature reading after the turbocharger.
Modular Turbo Options
The core kit supports several BorgWarner EFR turbocharger sizes.
• EFR 8474 for quicker response and a broad street-focused powerband
• EFR 9174 for a balance between response and high-power capability
• EFR 9280 for maximum airflow and increased top-end power potential
This modular design allows you to choose the turbocharger that matches your current goals while maintaining the same core manifold and installation platform.
OEM+ Fitment and Components
The kit includes properly selected coolant lines, oil lines, fittings, charge-air components, clamps, and mounting hardware.
The stainless steel 304 TIG-welded Y-pipe provides durable construction and clean exhaust flow. 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
• BorgWarner EFR turbocharger of your choice, 8474 or 9280
• Electronic wastegate mounting bracket and linkage kit
• Four-ply silicone hoses
• TIG-welded 304 stainless steel Y-pipe
• V-band clamp
• Silicone coolant hoses
• 14mm -6 AN the coolant feed and return lines
• Chargepipe
• 4 inch turbocharger inlet
• Stainless steel braided AN oil feed line
• Stainless steel turbo oil feed fitting
• Turbo oil drain adapter
• Aeroquip oil drain hose
• SmartSeal stainless steel hose clamps
• Oetiker hose clamps for Oil Drain and Coolant Lines
Why Choose the BigBoost S55 EFR Kit?
The BigBoost S55 EFR Kit combines full-frame turbo performance with a simplified electronic wastegate system.
You get:
• Strong turbo response
• High top-end airflow
• True twin-scroll exhaust pulse separation
• Efficient back-pressure levels under tested conditions
• No separate external wastegate system
• No added boost-controller plumbing
• Multiple turbocharger options
• OEM+ fitment and component quality
• A clean and serviceable installation
This is a complete S55 single-turbo platform developed for customers who want serious power, fast response, and fewer unnecessary components.
***These kits are made to order and may take around 4-5 weeks to be shipped***