BTKUSA G8X/X3M/X4M S58 Single Turbo Coolant Block Off Cap

BTKUSA SINGLE TURBO BLOCK OFF 

When converting the S58 to a single turbo setup, the small auxiliary water pump fitting located at the front of the engine is no longer used and needs to be properly blocked off.

Most single turbo kits solve this with a basic plastic cap. While it gets the job done, we felt this was one of those small details that could be improved. On a build where everything else is being upgraded, a cheap plastic cap sitting on the front of the cooling system never made much sense to us.

The BTKUSA S58 Billet Water Pump Block-Off Cap was designed as a cleaner, stronger, and more reliable solution for single turbo S58 applications. Machined from billet aluminum, this cap replaces the standard plastic plug with a more durable part that better matches the quality of the rest of the build.

This piece is made to block off the unused auxiliary port on the factory S58 water pump when removing or rerouting factory components during a single turbo conversion. It is designed for a simple, direct installation and gives the front of the motor a much cleaner finished look.

Instead of using an off-the-shelf plastic cap, we wanted to make something that felt intentional. It is a small part, but it serves an important purpose. Cooling system connections should be sealed properly, especially on cars making serious power, seeing high heat, or being pushed hard on the street and track.

Features:

• Designed for S58 single turbo conversions
• Blocks off the unused auxiliary fitting on the factory water pump
• Machined from billet aluminum
• Stronger and cleaner than a basic plastic cap
• Direct-fit design for simple installation
• Helps clean up the front of the engine bay
• Built for high-performance BMW applications

The BTKUSA Billet Water Pump Block-Off Cap is a simple upgrade, but it is the type of detail that separates a complete build from one that feels thrown together. Stronger material, cleaner appearance, and a better long-term solution for anyone converting their S58 to a single turbo setup.