The Toyota GR Corolla has proven itself to be a fantastically capable vehicle since its release, and the development team at Forge Motorsport have been able to work their magic once again to find further improvements. The next installment, is the release of the new upper airbox for the GR Corolla.
After continued testing and discussions with owners of GR’s, the stock airbox has proven itself to function well, especially with the stock map. However, the weakness in the airbox is most definitely the quantity and directional flow of the air. As such, we explored several different avenues, before settling on a replacement upper airbox that mounts to the stock lower. When used in collaboration with theForge Motorsport Inlet Duct performance car part, it ensures a consistent cold feed of air into the lower airbox that can then be delivered into a refined upper airbox. The increased diameter from 80mm of the stock inlet pipe to 89mm produces avolumetric increase of around 20%in just the connecting pipe from turbo inlet adapter to the airbox alone.
Due to the sensitivity of the MAF and stock map of the Yaris, a lot of testing was required to ensure that performance was gained without inflicting the driveability of the car - especially as we were changing from a panel filter to a cone filter and an increased diameter.
