TracTuff RBC/RBB Water Neck for 06-11 Civic Si/04-08 TSX

TracTuff RBC/RBB Water Neck Flange V2 – 2006–2011 Honda Civic Si / 2004–2008 Acura TSX

The TracTuff RBC/RBB Water Neck Flange V2 fixes the usual space and hose-routing headaches you run into on K-swapped cars. It’s a compact Civic Si water neck upgrade that works on the 2006–2011 Civic Si and 2004–2008 TSX, plus the 2003–2007 Accord and 2003–2011 Element. If you’re piecing together a K24A water neck this flange gives you clean routing without the bulky factory casting.

The K20Z3 billet water neck (SKU: TUF-TT-KWN-Z3-V2) uses 6061‑T6 aluminum and runs a -16 ORB outlet with a 1/2" NPT heater port. That means you can ditch sketchy adapters and run proper AN lines or a clean Civic Si radiator hose adapter setup. The low-profile body works in tight FWD bays and RWD or chassis conversions that need at least 1.562" between the cylinder head and firewall. It bolts to K24A/A2/A4/A8, K20Z3, and any RAA/RBB/RBC/RSP head, so it’s right at home on an RBC RB water neck style intake swap or a TracTuff water neck Civic street/track car.

Key Features

• 6061‑T6 billet aluminum TracTuff water neck for strength without excess weight
• -16 ORB outlet port so you can run proper AN lines and keep high-flow cooling on big-power setups
• 1/2" NPT heater port with options: run the heater, cap it, or customize routing
• Built for tight FWD bays and RWD K-series swaps where firewall and subframe clearance actually matter
• Cleans up hose routing compared to the stock neck and makes custom radiator layouts easier
• Direct fit for K24A/A2/A4/A8 and K20Z3 engines
• Works with RAA/RBB/RBC/RSP head castings, including common RBC water neck RSX and Civic setups
• Great match for custom radiators, tucked bays, and TracTuff billet water neck builds that see real track time

Included Hardware

• Four M8 socket head bolts for a solid, leak-free mount
• 90° heater hose fitting for easy heater core routing where space is tight
• 1/2" NPT plug if you’re deleting the heater or simplifying the bay
• Two O-rings to seal the flange and keep you from chasing leaks later

Vehicle Compatibility

• 2006–2011 Honda Civic Si (perfect for a clean Civic Si K24 swap water neck)
• 2004–2008 Acura TSX
• 2003–2007 Honda Accord
• 2003–2011 Honda Element

If you’re tired of fighting the stock casting, random adapters, or hacked hoses, this TracTuff RBC water neck RSX/Civic style flange gives you a compact, AN‑friendly layout that just works. It’s a solid upgrade for any TracTuff RBC water neck or RSX billet water neck style K build where you actually care about cooling and clearance, not just making it “good enough to run.”