BorgWarner 178788 1.00 A/R T4 Divided Turbine Housing for S400SX 87mm.

Upgrade your S400SX turbo with the genuine BorgWarner 178788 turbine housing. Designed specifically for the BorgWarner AirWerks S400 / S400SX series, this precision-engineered housing is sized for the 87mm turbine wheel and features a 1.00 A/R ratio that provides an excellent balance of responsive spool and high-RPM flow.

Built from high-quality cast iron, the 178788 offers outstanding durability under extreme exhaust heat and boost pressures. The T4 divided (twin-scroll) inlet preserves exhaust pulse energy for improved turbine efficiency and faster response, while the V-band / Half Marmon 4.62" outlet makes downpipe connections straightforward with common performance flanges and clamps.

Key Specifications

• A/R Ratio: 1.00
• Inlet: T4 Divided (Twin Scroll / Twin Flow)
• Outlet: V-band / Half Marmon 4.62" style
• Turbine Wheel Compatibility: 87mm (87.37mm) OD
• Material: High-grade cast iron
• Wastegate: External provision (actuator not included)
• Finish: Natural cast
• Series: BorgWarner S400SX, S400SX-E, AirWerks S400

Performance Benefits

• 1.00 A/R strikes the sweet spot for most diesel performance applications — quicker spool than 1.10 or 1.25 housings while still supporting serious horsepower without excessive backpressure.
• Twin-scroll divided volute improves exhaust scavenging and turbine efficiency.
• Ideal for street-driven trucks, drag racing, sled pulling, and custom single or compound turbo setups.
• OEM-quality BorgWarner engineering for reliable, leak-free performance.

Fitment Notes

• Fits BorgWarner S400SX / S400SX-E and compatible S400 series turbos using an 87mm turbine wheel (commonly used on S472, S475, S476, S480, S482 configurations).
• T4 divided inlet works with twin-scroll / divided T4 manifolds.
• Universal fitment across many high-horsepower diesel platforms (Cummins, Power Stroke, Duramax, and custom builds). Always verify your specific turbo model and manifold.