Our K series NC upper coolant neck for the K24A2 (RBB) and K20Z (RBC) style cylinder heads is specifically designed to make radiator hose routing easy in the NC. 

We machine the base out of 6061 aluminum and then weld on a 1.25” inlet pipe to position everything neatly in the engine bay. The coolant neck features a ½” NPT port for the heater hose, and also a plug for those deleting heat. 

An extra 1/8" NPT to 3/8" barbed 90 degree fitting is also provided, and threads into the available port in the coolant neck. This gets routed to the factory NC coolant overflow tank to complete the installation.