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TracTuff RBB/ RBC Rear Wheel Drive K Swap Water Neck Kit


I have combined three popular products into a single kit for quick and easy purchasing!

Products shown are also available individually at each of these links. You can either go to each of the pages and read the product descriptions or read them all below.

Water Neck 

Thermostat Cover

Water Bypass Adapter

Water Neck

The RWD upper water neck addresses a few concerns with the growing popularity of the k swapping a number of front engine rear drive chassis. Now fabricated with a one piece tube!!!

Normally, the water neck is pretty much right in front of the radiator and the two points are pretty much equal in height... and even then, the K is notorious for being a real bitch to bleed! Rotate the motor 90° and now you have make the radiator hose either go up and over or down and under the intake manifold. Both will present problems, but one is uglier than the other, so down and under it is. Lucky for you, I have created a fixture based off of the S2000 outlet, had custom tubes bent, and have welded them to my billet RWD housing... essentially mimicking the geometry of the factory S2000 intake manifold/ water neck assembly.

This option has allowed K swapped S2000's to reuse the factory upper hose and I'm starting to see more and more Non-Honda swaps going to that hose to solve there unique swaps connection issue. The only short coming of this design, is that when taking the cooling systems highest point and ask it do dive down under the intake manifold, you are creating a HUGE pocket for air to collect! For this reason, I highly recommend a swirl pot, a fill pot, a filler neck, or at the very least... a vent (pictured) (listed in order of best, better, good). Each of those product offers a way to eliminate the air on initial fill up where the best option constantly deaerates the coolant (read more).

NOTE: Made to Order - Contact for ETA - If you are interested in a running AN lines or a specific design, please email The tube is welded so that it sits similarly to the OEM S2000 water neck outlet position when the engine sits at its original 15° lean to the passenger side (exhaust side). The billet neck has a 1/2" NPT heater port and the hardware kit includes a 5/8" hose fitting, a plug, four stainless M8 socket head bolts, and a Genuine Honda gasket. If you choose the bleed port... you will also get a plug. The tube is welded so that it mimics the S2000 outlet position when bolted to an engine leaned back 15° (OEM position). The Skunk2 Ultra Street and Ultra Race intake manifolds require a small change to the outlet position in order to avoid the plenum flange but the end of the tube is still VERY similar to the OEM S2000 water necks outlet position.

Thermostat Cover

The TracTuff K Series Billet Thermostat Cover is NEWLY REDESIGNED to fit all plastic k series housings!!! 

Originally offered as a configuration option but due to customers complaining that the options were confusing, I have decided to give the common RWD selection its own spot. No cool features, no weaknesses, no bullshit! What you see is a simple Billet Thermostat Cover that bolts to the OEM plastic housing, uses the OEM shoulder bolts, the OEM thermostat, and OEM gasket for pretty much any RWD k swap. I chose the original thermostat because it is unique to this engines configuration and is related to many of customers number once concern. You wont find any sensor ports because they don't belong here and you wont find a swivel because it doesn't work for everyone anyway. What you do get is, a straight forward, refreshing design that allows the end-user to chose whichever fitting he/ she needs to plumb the lower hose.

Machined from US milled 6061 aluminum; the flange incorporates an OEM o-ring grove and the front (originally threaded for -16 ORB) has been machined to remove the material beyond the thermostats locating pin, reducing the overall length and welding a straight section of 1-1/4" tube or a -16 male flare. The Billet Thermostat Cover uniquely receives the K20a2/ K20a3/ k20z1 thermostat for the most reliable function and retains the quick warm up feature of the water bypass circuit. 

NOTE: The REDESIGNED cover fits the two housing patterns scattered throughout the various models... BUT understand the new housing is not perfect. If you are using the housing from a K20A2/ K20A3/ K20Z1 engine code, the cover fits natively. If you are using the housing from any other k series, you will need to select the "All Others" mod or you will need to make a modification to the aluminum water pump housing OR trim the billet cover. Yes, I said trim the brand new billet cover! Sorry. You can choose to trim it yourself or you can have me do it at no charge. In order to run this product, you still MUST use the thermostat (not included) from a 2002-2006 Acura RSX or 2002-2005 Civic Si (P/N: 19301-PNA-003). The S2000 and Miata k swap benefits from this configuration the most, but as more and more chassis are being k swapped, I imagine others will as well. Price includes a new Honda gasket.

This is the "All Others" Mod

Water Bypass Adapter

The OG water bypass adapter! Imitated but not duplicated. Still the best looking, best fitting (leak free!), and now the least expensive!

My water bypass allows RAA, RBB, RBC, and RSP cylinder head owners to run the more popular aftermarket intake manifold options that were designed for the earlier PRB/ PRC flange. The PRB/ PRC style manifolds do not have an integrated coolant passage so the coolant bypass hole is left open when used together. Even if you don't plan on running a PRB/ PRC style manifold... there are plenty of benefits that make this product a smart purchase! Benefits such as a reduction of intake manifold temps by eliminating the heat transfer/ heat soak associated with hot coolant running through the manifold. By simply modifying the manifolds flange (cutting off coolant portion) and running this adapter, the coolant is kept away from the manifold completely, just like what you would find on the earlier PRB/ PRC heads. NOW your Hondata IM gasket will really work!! I've personally seen drops in temp 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! It makes that job a real SNAP.

NOTE: Starting 4/16/20 ALL water bypass adapter sales will include a 90° 1/2" NPT to 5/8" hose fitting as STANDARD. You no longer have the option of buying a plug... if you are interested in deleting the water bypass hose and its function, please check out my new dedicated Water Bypass Block-Off.