TracTuff RBB/ RBC Water Bypass Adapter Filler Neck


Over the years I have been challenged with making several upper water necks, filler necks, fill pots, and swirl pots that fit with crazy sidewinder turbo manifolds and huge turbos! Some of these jobs have presented such unrealistic situations that it has left the job near impossible to complete with the budget being offered. Enter the Water Bypass Filler Neck!! A spin on our VERY popular water bypass adapter for the K20Z3/ K24A2 that allows RAA, RBC, RBB, and RSP cylinder head owners to not only run the more popular aftermarket intake manifold options that were designed for the earlier PRB/ PRC flange BUT also adds cooling system fill point! Eliminating the conflict of a filler being placed in close proximity to the turbo inlet and complicating plumbing.

In addition to the awesome feature of being able to fill your cooling system from the highest point... the water bypass adapter is known for reducing intake manifold temps by eliminating the heat transfer/ heat soak associated with hot coolant running through the manifold. By modifying the manifolds flange (cutting off coolant portion) and running our adapter the coolant is kept away from the manifold completely, just like what you would find on the earlier PRB/ PRC heads, so NOW your Hondata IM gasket will really work!! We've seen drops as much as 18°!! Not to mention, the additional benefit of no longer having to drain the coolant when removing the intake manifold for maintenance or swaps... makes things a real SNAP!

NOTE: Made to Order - Contact for ETA - If you are interested in a specific design that varies from this, please email us at sales@tractuff.com. If you have questions related to the configuration or options... PLEASE visit the WHATS WHAT or FAQ page. The cap bung has a 1/16" NPT port for connection to an overflow and uses early model Honda radiator caps; such as an 88'-91' Civic/ CRX or 90'-93' Integra.


Installation Guide

The manifold shown is JUST AN EXAMPLE... I'm not going to re shoot instructions for every manifold out there! As long as the aftermarket manifold you own has the same shape as the PRB/ PRC manifold (like the one shown) and they did a good job of holding to Honda's tolerance, my adapter will fit perfectly! This was the first product on the market and its been flawless since 2012.

If the shape of the products right edge DOES NOT LINE UP with the edge of the cylinder head, the set screw whole will not line up. If it DOES NOT LINE UP.... this is not a water bypass adapter problem, it is an intake manifold problem. As mentioned above, if the manufacture did NOT hold to Honda's tolerance (shape) you will have to modify one of the two parts, where they are coming in contact.

Start by installing the o-ring into the recess on the adapter’s backside and set the adapter aside.

Update: Nowhere in this write-up do I mention OR recommend the use of Hondabond or an RTV sealant... this is NOT an oversight or accident. I don't mention it or recommend it BECAUSE IT DOESN'T NEED IT!! The o-ring seals DIRECTLY AGAINST THE CYLINDER HEAD.


Grab the stainless steel link and the 35mm Genuine Honda flanged bolt. Install the bolt into the unthreaded hole in the link.



Install the bolt and stainless link into the right-most intake manifold flange bolt hole. Tighten lightly with the link facing upward.


Grab the shorter 12mm socket head bolt and adapter and install the bolt into the lower bolt hole.

Take the bolt and adapter and install it over the exposed water & egr ports. Thread the bolt into the cylinder head until it is hand tight. Do NOT install the adapter over a gasket of any type!

Grab the stainless steel set screw and thread it into the stainless link. The pointed set screw will tighten into the hole well but in some extreme cases it may be a good idea to use some medium grade Loctite.

Swing the stainless link and set screw down until it lines up with the pilot hole of your choice (only one choice now). 

Tighten the 8mm intake manifold and Water Bypass bolts to 18 lb. ft. of torque and tighten the set screw until you have sufficient crush on the adapters o-ring. The thin 8mm jamb nut is not shown here but it would either go on the exposed threads of the set screw (face of the link) if there were enough threads OR in between the link and the bypass adapter (shown) and tightened to lock the set screw in place. Congratulations! You're done.