![Engine : B58 Charge Cooler Fitting](http://williamsperformance.co.uk/cdn/shop/products/image_60b61c71-022e-4f47-83e3-40c81ebc1f27_700x700.jpg?v=1664527308)
The B58 turbo engine of the specified BMW models is equipped with an indirect charge-air cooling circuit. So the cooling of the charged air is not realized by the ambient air as cooling medium (as usual), but made with its own cooling water circuit. A reduction of the temperature of the cooling water is directly equated with an improved cooling performance of the charged air.