


The factory coolant port on an RBC head is bulky, ugly, and locks you into hose routing you probably don't want. If you're tucking a bay, moving to AN plumbing, or just tired of looking at the stock piece, this coolant port adapter replaces it with something compact and machined that puts you in control of where your hoses go. It's cut from a single piece of 6061 aluminum, finished in black anodize, and it gives you a -16 ORB outlet you can run either way, factory-style radiator hose or full AN.
This adapter is built for front-wheel-drive applications. If you're putting one of these engines into a rear-wheel-drive swap, the coolant routing is different and we make a separate adapter for RWD. Grab the right one for your layout so you're not fighting hose angles that were never going to work.
This is the decision most people are weighing, and the adapter handles both without you buying a different part. There's an additional heater port you configure at install.
Keeping the heater? Use the supplied threaded fitting and your factory heater core stays connected and working. If you daily the car or live somewhere with real winters, go this route. There's no performance penalty for it.
Doing a heater delete? Cap the port with the included -8 ORB plug and you're done. Cleaner bay, fewer hoses, one less thing to leak. That's the move for a track car or a dedicated build where the heater circuit is just dead weight taking up space.
Both options ship in the box, so you decide with the parts in your hands rather than at checkout, and you can change your mind later if the car's purpose changes.
The outlet is a threaded -16 ORB, and that's what makes this flexible. Use the included -16AN to hose barb adapter and you're running standard factory-style radiator hoses, no fuss. Or thread in a -16 AN fitting and plumb the entire cooling system in AN line if that's where the build is going. You're not locked into one path, and you're not buying a second housing if you change your approach down the road.
Here's where this differs from a lot of adapters out there. The internal coolant passage is fully machined rather than left as-cast, so coolant moves through the housing smoothly instead of hitting rough surfaces and restrictions. That matters, because a cooling part that looks great and flows poorly is a bad trade on a car you actually drive hard. You get the compact, clean appearance without giving anything up on the cooling side.
Everything you need to install it, nothing to source separately:
| Engine | Vehicle | Years |
|---|---|---|
| K20Z3 | Honda Civic Si | 2006-2011 |
| K24A2 | Acura TSX | 2004-2008 |
| K24A4 | Honda Accord / Element | Accord 2003-2005, Element 2003-2006 |
| K24A8 | Honda Accord / Element | Accord 2006-2007, Element 2007-2011 |
| K24Z7 | Honda Civic Si / Acura ILX | Si 2012-2015, ILX 2013-2015 |
It also fits these engines in swaps, since it mounts to the head rather than the chassis. If you've got an RBC head and you're front-wheel drive, this is your adapter.
This is for the builder who cares how the bay looks and how the car works. Tucking a harness and wanting the coolant side to match, converting to AN plumbing, deleting a heater on a track car, or just replacing a tired factory housing with something better made, this handles all of it out of one box. Pick your heater configuration, thread in the fitting you want, and get a cooling setup that looks like somebody planned it.
Fits: RBC-head K-series engines, K20Z3 (06-11 Civic Si), K24A2 (04-08 TSX), K24A4 (03-05 Accord / 03-06 Element), K24A8 (06-07 Accord / 07-11 Element), and K24Z7 (12-15 Civic Si / 13-15 ILX), front-wheel-drive applications. RWD swaps use our separate adapter. Material: single-piece 6061 aluminum, black anodized. Outlet: -16 ORB, works with the included hose barb adapter or an aftermarket AN fitting. Heater port: retain with the supplied threaded fitting or seal with the included -8 ORB plug. Coolant passage: fully machined for unrestricted flow. Includes: adapter, stamped steel gasket, mounting hardware, -8 ORB plug, threaded heater fitting, and -16 ORB to hose barb radiator fitting.
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