Introducing the FA24 Engine

The 2022+ WRX is equipped with the FA24 engine, which features an electronically controlled factory diverter. This is a shift from the pneumatic bypass valve that was used in previous turbo Subaru engines.

What’s New?

This new setup is managed by the ECU, which might sound impressive at first glance. However, it does come with some trade-offs. While the electronic valve may respond to throttle closures quicker than its pneumatic counterpart, there are concerns regarding its longevity and boost sealing. The valve mechanism is made entirely of molded plastic, which raises some questions about durability.

Throttle Response and Drivability

One significant downside is that the factory electronic valve operates in a binary manner—it can only be fully open or fully closed. This limitation can lead to less-than-ideal throttle response and overall drivability. It's a change that might leave some enthusiasts longing for the more nuanced control of previous systems.