BorgWarner Turbine Housing EFR B2 74mm 1.45 T4 Twin Scroll (H Type)

This is the BorgWarner EFR B2 turbine housing, designed for high-performance turbocharger setups. It features a 74mm inducer diameter and a 1.45 A/R (area to radius) ratio, which is crucial for determining how quickly the turbocharger spools up and at what engine speeds it can efficiently move exhaust gas. The T4 twin-scroll inlet flange is a popular choice for serious tuners, offering a strong foundation for custom builds where precise control over boost response and power delivery is key. This housing is specifically the 'H Type', indicating a particular internal wastegate port configuration, though it's important to note that this specific model is not CARB approved and cannot be shipped to California.

The twin-scroll design is a notable feature, as it separates the exhaust pulses from cylinder pairs that are not adjacent in the firing order. This separation helps to reduce exhaust manifold backpressure and improve the efficiency of the exhaust gas flow into the turbine wheel. This can lead to quicker turbo spool and a broader powerband compared to a single-scroll housing. The 1.45 A/R ratio is on the larger side, suggesting this housing is intended for applications focused on high-RPM power output and sustained boost, often paired with larger engine displacements or more aggressive camshaft profiles. BorgWarner is well-known for its robust construction, and this turbine housing is built to withstand the high temperatures and pressures associated with performance forced induction systems.

When planning your build, consider that this turbine housing is a component of a larger system. You'll need to ensure compatibility with your chosen BorgWarner EFR center section and exhaust manifold. Proper exhaust manifold design is critical for twin-scroll applications to maximize the benefits of the separated scroll design. Due to its performance-oriented nature and the specific A/R ratio, this housing is best suited for custom turbocharger builds where the engine's tuning and supporting modifications are carefully matched to achieve optimal results.