Product Description
BORG WARNER 178790 S400SX Turbine Housing 87MM 1.25 A/R T4 (Twin-Scroll)
The BorgWarner 178790 S400SX Turbine Housing is a genuine AirWerks S400SX replacement and upgrade housing designed for 87mm turbine wheel applications. Featuring a large 1.25 A/R twin-scroll T4 inlet and durable cast-iron construction, the 178790 is engineered for maximum exhaust flow, reduced drive pressure, and exceptional high-horsepower performance in demanding diesel applications.
Designed for use with BorgWarner S400SX turbochargers utilizing an 87mm turbine wheel, this housing is a popular choice for S472, S475, S476, S480, and S482 turbocharger combinations. The twin-scroll T4 design improves pulse separation and turbine efficiency while supporting strong top-end power, making it an excellent option for large single turbochargers and atmospheric compound turbocharger systems.
Features
- Genuine BorgWarner AirWerks S400SX turbine housing
- Fits S400SX turbochargers with 87mm turbine wheels
- 1.25 A/R turbine housing for maximum top-end airflow
- T4 divided twin-scroll inlet flange
- Twin-volute design improves exhaust pulse separation
- Helps reduce drive pressure in high-horsepower applications
- Heavy-duty cast iron construction
- Excellent choice for large single turbo systems
- Ideal atmospheric housing for compound turbocharger setups
- OEM BorgWarner fit and durability
Fitment
- BorgWarner AirWerks S400SX turbochargers
- S472 turbocharger applications
- S475 turbocharger applications
- S476 turbocharger applications
- S480 turbocharger applications
- S482 turbocharger applications
- 87mm S400 turbine wheel configurations
- High-horsepower diesel performance builds
- Single turbocharger systems
- Compound turbocharger systems
Note: This is a turbine housing only and does not include the turbocharger center section, compressor housing, turbine wheel, clamps, or installation hardware. Verify turbine wheel dimensions and housing compatibility before ordering.
What's Included
- BorgWarner 178790 S400SX Turbine Housing
- 1.25 A/R Twin-Scroll T4 Housing
Specifications
- Manufacturer: BorgWarner
- Part Number: 178790
- Turbo Series: AirWerks S400 / S400SX
- Turbine Wheel Compatibility: 87mm S400 Turbine Wheel
- Housing Style: Twin Volute / Twin Scroll
- Inlet Flange: Divided T4
- A/R Ratio: 1.25
- Outlet Connection: 4.62 Inch Marmon / V-Band
- Construction: Cast Iron
- Application: High-Horsepower Diesel Performance
- Primary Use: Large Single Turbo and Compound Turbo Systems
Cross Reference Numbers
178790, 178787, 178788, 178789, 177105, 177104, S400SX 1.25 A/R T4 Housing, S400 Twin Scroll Housing, AirWerks S400SX Housing
FAQ
What turbochargers does the BorgWarner 178790 fit?
The 178790 is designed for BorgWarner S400SX turbochargers utilizing an 87mm turbine wheel. Common applications include S472, S475, S476, S480, and S482 turbocharger combinations.
Will the 1.25 A/R housing spool slower than a 1.00 or 1.10 A/R housing?
Generally yes. The larger 1.25 A/R housing prioritizes maximum airflow, reduced drive pressure, and top-end horsepower at the expense of some low-RPM spool response.
Is this housing twin-scroll?
Yes. The BorgWarner 178790 features a divided T4 twin-scroll inlet that helps improve exhaust pulse separation and turbine efficiency when paired with a divided manifold.
Is this a complete turbocharger?
No. The 178790 is a turbine housing only and does not include the CHRA, compressor housing, turbine wheel, or installation hardware.
What is the outlet size?
The housing utilizes a 4.62-inch Marmon-style V-band outlet commonly found on S400SX performance turbocharger applications.
Who should choose the 1.25 A/R housing?
This housing is best suited for high-horsepower diesel applications, large single turbocharger setups, and atmospheric compound turbocharger systems where maximum airflow and reduced drive pressure are priorities.
