Description I pioneered the Water Bypass Adapter over 16 years ago, and it remains the best-fitting and most problem-free (leak-free) solution available today. Despite the concept (not the design) being copied multiple times. Introduced in 2010, so the K20Z3 and K24A2 engine owners could use aftermarket intake manifolds that were designed for the previous generation k series cylinder head. The K20Z3’s RBC (casting), the K24A2’s RBB (casting), and all those like it (RSP and maybe others) have a water passage incorporated into the intake manifold, and popular aftermarket options do not. Using an intake manifold designed for the PRB/PRC cylinder head will leave the right-most portion of the intake manifold’s flange exposed, rendering both the coolant bypass and EGR passages unusable. My water bypass adapter allows you to make the water passage connection as well as cover the ugly EGR passage. Even if you don’t plan on running an aftermarket intake manifold, you can realize the benefits of reduced intake manifold temps by eliminating the heat transfer associated with hot coolant warming the manifold and no longer needing to drain and re-bleed the cooling system every time you remove the intake manifold for maintenance or swaps. NOTE: The hardware kit includes an M8 flanged hex head bolt, an M8 socket head bolt, an M8 high-point set screw, a thin M8 jamb nut, a high-temp o-ring, a stainless steel link, a 90° 1/2″ NPT to 5/8″ hose fitting, and a hose clamp. The sensor port is OPTIONAL. If you DO NOT have a sensor with either thread listed… DONT SELECT IT!! I only offer 1/8″ NPT or 1/8″ BSPT (Honda Single Prong Sensor). If you are interested in deleting the water bypass hose and its function, please check out my dedicated Water Bypass Block-Off. Installation Guide Please understand that the intake manifold shown is JUST AN EXAMPLE. My water bypass adapter was designed and machined for a perfect fit when using the Genuine Honda PRB/ PRC intake manifold shown and should fit the same with ALL intake manifolds that hold that shape. I cannot control the shape of intake manifolds that have been cut/ modified nor the shape aftermarket companies have designed. Again, I used the shape found on Genuine Honda intake manifolds and that should be the standard for ALL. If the water bypass adapter does not fit properly, it is safe to say that the manifold casting is to blame, and you will need to make a choice on which of the two products will be modified. I recommend you remove material from the manifold so you don’t accidentally remove material from the water bypass adapter that will cause a leak. Also, nowhere in this write-up do I mention the use of OR recommend Hondabond or any RTV sealant. This is NOT an oversight or accident. It is NOT needed. The only thing you need to do is apply Teflon tape to the fittings threads; the o-ring seals directly against the cylinder head. Do NOT install the water bypass adapter on top of any type of gasket!! The water bypass adapter does not support EGR. By purchasing this product, it is assumed that you either don’t have an engine with a complete EGR system or you have deleted it by using a water neck that renders the passage useless. Start by wrapping the threads of the 90° hose fitting with Teflon tape. If you have never applied Teflon tape to a fittings threads… please watch this video. There is a right and wrong way of applying it. Install the hose fitting in the water bypass adapter and then install the o-ring into the recess on the adapter’s backside and set the adapter aside. If you need assistance with keeping the o-ring in place… use a small dab of Hondabond or grease. 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 35mm Genuine Honda flange 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. 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.
