BorgWarner Turbine Housing SX S400 T4 A/R .90 Twin Scroll

This BorgWarner turbine housing features a .90 A/R ratio, which is a key measurement that helps determine how much exhaust gas can flow through the housing. A larger A/R like .90 generally allows for better exhaust flow, which can help your turbocharger spool up more efficiently and make more power, especially at higher engine RPMs. This housing is designed for the S400 frame turbocharger and uses a T4 flange with a twin-scroll design.

The twin-scroll design separates the exhaust pulses from each bank of cylinders in a V-engine, or from individual cylinders in an inline engine, directing them into separate passages within the turbine housing. This separation helps to improve exhaust gas velocity and can lead to quicker turbocharger spool-up and a more responsive feel. The housing itself is well-built from durable materials to withstand the high temperatures and pressures found in forced induction systems.

This turbine housing is a direct replacement for BorgWarner S400 turbos with a T4 twin-scroll inlet. Ensure your turbocharger frame and flange type match this housing for proper installation. It's important to note that this part is not CARB approved and cannot be shipped to California.