K SWAP GUIDE (part one) RBC/RRC manifold, Throttle body tech, K-tuned adjustable EP3 pulley

K SWAP GUIDE (part one) RBC/RRC manifold, Throttle body tech, K-tuned adjustable EP3 pulley

For the first installment of the multi part k swap guide, I’m going to discuss fitting an RBC/RRC manifold, and installing a K-tuned adjustable EP3 pulley. I know that doesn’t sound like a lot, but trust me there are some important things I’ll be going over as well as some tips and tricks to make your life a little easier. For anyone that is doing a K swap I would recommend getting an RBC intake manifold, not only does it look 100x better than the stock PRC/PRB K20 one but it will increase some horse power too, even on a stock motor. You can read about this on Super Streets K series intake manifold shoot out by clicking the link below.


Now that article is a bit dated by today’s standards, and there are some great manifolds out now days. But for a stock/mild K20 the RBC will yield best bang for the buck. They can be purchased used for 100-150 bucks, or brand new for 250 bucks.  Obviously the RRC manifold (the more expensive option) can produce some great power too, but its cost is pretty steep when you consider that fact the you could get a ported RBC manifold and make better power for pretty much the same price. Despite this fact, I do have an RRC on my K20. Just because of the fact that its 100% bolt on, OEM,  and I’ll never have to worry about in the back of my mind thinking that if I had gotten a ported RBC would it be possible that the port job wasn’t good, and in turn actually robbing some power.

For me the K tuned EP3 adjustable pulley is the easiest solution, and it’s cheaper than the relocation kit. You must run either one of these kits if you are deleting the power steering  (which most of you should be) The “universal A/C & P/S eliminator kit” needs you to change the pulley on the alternator its self, and it puts the alternator lower in a hard to access/service place. Again this is strictly my own opinion, and I have personally used the EP3 adjustable pulley on two separate K20 swaps, and I have been issue free. But Pat has actually had the bearing for the pulley go out on him before, and this does appear to be somewhat common amongst fellow track enthusiast. Now I can’t be certain that this isn’t due to improper adjusting/tension of the belt when installed, because I have had mine for longer than Pat and haven’t had any issue. Either way there is a cure for this, you simply have to go to the auto parts store, get a better bearing and that will take care of that. Since that is the only moving part of the EP3 kit, there is less to go wrong as compared to the A/C & P/S eliminator kit.

Let’s install an RBC/RRC intake manifold! First thing you are going to want to do is remove the stock PRC/PRB intake manifold. This will allow you to easily test fit the RBC/RRC manifold during the cutting/grinding process.


As you can see above the intake manifold won’t be able to completely come off because there is the water pump, pcv, belt tensioner unit in the way. You must create some space, there is NO way it will come off unless you do.

To create space, start by removing the x3 12mm bolts holding the alternator on. Then you are going to loosen the x4 14 mm bolts (one of them is a nut) holding the whole assembly to the block. (you don’t really need to completely remove the bolts just loosen them enough to get the unit to come off the block about 1/2-3/4 inch)

You are then going to use a pry bar, and carefully pry back the assembly about a half inch away from the block to allow the manifold to come off. DON’T GO CRAZY when prying, and pay attention to what you’re prying on so you don’t damage anything.


Above you can see how I only needed a little bit of clearance, now just simply bolt back down all four bolts (one of them is a nut) evenly and you’re set. You can also see above how there are two studs that come out of the head for the intake manifold, and if you have made it this far then you know those were the reason you couldn’t just take the manifold off with ease.

Pro tip, we are going to remove these two studs and you will only use bolts to attach the intake manifold. This will allow you to easily remove the manifold in the future with out having to take all that other stuff off.


Im going to use the double nut to nut trick to remove the studs. I don’t have a stud remover, but that is a such tool and would make life a littler easier.

  1. Take two nuts and screw them on back to back.
  2. Take two wrenches and tighten them as hard against each other as possible.
  3. Now take the wrench that is trapped between the head and the nut, and simply turn it counter clockwise. this will loosen the stud.
  4. Once the stud is loosened take your two wrenches, place them on both nuts, and break them lose somewhat from each other (still snug enough to spin the stud all the way off, but not so tightly that its hard to loosen them apart once the stud is completely removed from the head.)


do this for both studs, and now you should have no studs coming out of the head.


Now that you have removed the stock PRC manifold, lets install the RBC/RRC intake manifold.


So of course Pat decided to go with a brand new RBC manifold from Honda. Honestly its only about 100 bucks more than a used one. So to save yourself the headache of dealing with people selling shitty shit, scamming, or just the convenience of having it shipped to your door, its a much better option. BUT, I have bought used ones before and have had no issues. You just have to know what to look for… Make sure none of the threaded holes are stripped out. You can do this by brining a few bolts that will thread into each different sized hole, them simply thread in and make sure there is no resistance or hard spots while threading. Make sure you check the holes where the throttle body bolts up, sometimes people will use bolts that are too long and it can crack the manifold, or cause a vacuum leak. I honestly wouldn’t buy one that has already been cut unless it’s from someone that is reputable, you can really mess it up if you cut wrong. Other than that, its just a cast piece of aluminum that delivers air to the engine. There is no moving parts to wear out, or any other way than the ones I listed above that would make it not work. Also pay close attention if you are buying a used one that has been shaved, because maybe you will need to utilize the holes that were shaved.

To make an RBC/RRC manifold fit on a K20a/a2/z1 head, you’re going to need to cut off the water neck part. You can see in the pictures below what the difference in heads looks like from Pat’s old K20a RBC euro r motor (tsx/accord), to the new JDM DC5 PRC/PRB K20a type r motor.


Above you can see how the PRB head (red valve cover) has the upper coolant outlet on the front of the head, where as the RBC head (teal valve cover) has the upper coolant outlet on the side of the head.


Above you can see how the stock PRC intake manifold is separate from the upper coolant outlet.

Below you can see the differences of the two manifolds stacked on top of each other. You can start to get the idea of what part you have to cut off the RBC/RRC manifold to make it fit.


Here is what you will need to prep for cutting.

  • Really long extension (or something similar).
  • RBC/RRC manifold.
  • Marker.
  • Oem intake manifold gasket.


Take note that the Gasket only goes one way. Below I have it the wrong way just for reference, as you can see two of the holes don’t line up (the finger is pointing to one).


Below I flipped it, and you can now see that all holes on the gasket line up with the manifold. (see finger)


I just simply slide 4 bolts in to line up the gasket somewhat and keep it from falling off.


Once I’m ready to begin marking what I need to cut, I take my two fingers and center the gasket (you will be able to feel with your fingers when its even)

You will take the marker you have and trace along the edge of the gasket. Remember! you are using the OEM PRC gasket that came off the K20a/a2/z1 head, because this is what you are making the manifold fit onto.



What you are left with is a guide of what you need to cut off.

Now we need to move the water neck out of the way. This is a pro tip, the water neck is steel and will be hard to cut compared to the aluminum of the manifold, not to mention it can be in the way of cutting.


Take your long extension (or anything that will fit in the water neck hole) the longer the better. You are now going to rotate the water neck out of the way 180*, which will make it easier when cutting. You don’t have to worry about damaging the water neck because you won’t be using it as it will be cut off.


No you are going to just make a straight cut to get the main part off the manifold. Don’t worry about trying to follow the curvy line, you cam simply use a flappy wheel to carve out the design.


Be cautious when cutting so you don’t cut thru something on the back side that you need. Make sure you properly plan out your cut and the path you’re going to take before you even turn on the cut off wheel. Now you can also see why I turned the water neck the opposite direction.


Now take a flappy wheel and grind away the curves so it fits proper around the water neck on the head.


Above is what you should end up with. Take your time when doing this, if you scuff, mark, mar up, or damage any part of the mating surface you are most likely going to have a vacuum leak. PAY ATTENTION to how much you are removing you can test fit it as many times as you need, so there is no need to grind it all off in one session.

Most people would be too scared to try this, but it’s actually easy. The prep is the most important part of this, and visualizing where your cuts will go before actually making them is the key to success.

Once all cut and ground down, make sure you blow it out throughly with an air compressor, or spray liberally with brake clean. You don’t want any of that metal shaving going into your engine.


Above you can see how it is a tight squeeze, but just test fit as you are grinding to make sure you don’t take too much off.

Im sure you already noticed that there was a thermal intake manifold gasket installed, but here is a picture anyway of some necessary parts to complete the manifold swap. (please disregard the spoon drain plugs, we will be covering those in another part of the series)


So a PRC/PRB k20a,A2,Z1 throttle body won’t directly bolt up to a RBC/RRC manifold. There a many companies that make an adapter kit so you can utilize the stock TB with the RBC/RRC manifold. Karcepts, K-tuned, and Hybrid racing are the top three. Don’t waste you time getting any cheap/knock off ones, they will only have you chasing vacuum leaks.

Some people say that a thermal intake manifold gasket is too thick and will not allow the bolts/nuts to get tight enough and over time they will vibrate loose. Well I have had mine on my K20 for 5 years with out incident, and as you can see in the picture below there is plenty of threads on the bolt. (the bolt is pushed to the head, but the hasn’t been threaded)


The K-tuned TB adapter has a Ring that can be removed so you can either run the stock TB or a ported/larger TB with out having to port the adapter.


It’s also worth noting that the kit comes with a gasket for the adapter to the manifold, but not one for the TB to the adapter. For this you will need to order one for the PRC/PRB intake manifold (since that’s what your throttle body is for)


This is what it looks like all put on. Make sure when you bolt the manifold on that you use all the same length bolts (you will be short two bolts since they were studs before you removed them) so make sure you match up two other bolts to the original bolts that were holding the manifold on.


On top of the throttle body there is a sensor you will no longer need, The purge control solenoid. It’s the one directly on top of the TB with the bronze metal around it. Simply loosen the Phillips screw holding it in, and twist/pull to remove. There is a rubber grommet that will make it difficult to remove sometimes, but just keep twisting and pulling.

Now in your K- tuned TB adapter kit there will be a rubber plug that you will jam in the existing hole to stop any vacuum leak.


Pro tip, spray some WD-40 on it to help it slide completely in. The WD-40 will dry by the time you start the car.


It will not go completely in, don’t worry. Im sure you also noticed that I removed the throttle cable bracket, and the other vacuum line bracket. You will not be reusing these, and you will need to get a throttle cable bracket that is for a K swap vehicle. We will go over this in the next installment of the series. You will also need to block the hole on the new RBC/RRC manifold where the MAP sensor would go. K-tuned makes a cool block off plug.


Now let’s move on to the IACV. You have two choices here, you can either remove it and get a block off plate. But you will need Hondata or some other programable ECU to disable the sensor so it doesn’t throw a check engine light. Or you can just chose to leave it on and plugged in. I have opted to leave mine plugged in on my car and Pat has opted to block his and disable the sensor in Kpro. There is no difference other than aesthetics.


So here is the IACV…


The IACV is almost always the culprit for surging idle when you first do a swap. The sea air will cause oxidization to occur which can clog, or block the IACV from functioning  properly. A while back I did a HOW TO: clean the IACV, you can read all about it by clicking the link below


Patrick will not be running a IACV, instead he will be using the Karcepts block off plate off his old motor.

Below are some pictures of what a gunked up IACV looks like. (this is the one I just removed from his new motor)


The mechanism in here is what needs to freely spin. The oxidization usually stops it from being able to freely spin, thus giving you the dreaded idle surge.  To read how to completely disassemble and throughly clean this click the link above.

Now if you opt to keep your IACV bolted on, assuming you have cleaned it. All you need to do is block off the two nipples with some rubber caps.


But of course pat is not keeping his.


Make sure you remove ALL the old gasket material. Time spent here is worth it to not have to trouble shoot a vacuum leak later on once the car is running.


I just use a razor blade to carefully remove the old gasket.


Then clean the rest of it off with a scotch bite pad.


Remember you need a new OEM PRC/PRB TB gasket. Now bolt your TB on.



Looks much cleaner with out all the accessories on it.

Now we must remove the Idle air asset valve. This will not be necessary,  your car will run fine without it, and not throw a CEL for it not being utilized. I have personally run a bone stock ECU with no issues, or CEL’s.


I break off the nipple coming out of the side of the air assist valve, this will allow you to completely rotate the valve off. Otherwise you would need to remove the valve cover for it to completely spin. The plastic is very brittle so I just tap to with a large solid object, it will just snap off.


Now take a 22mm wrench/socket and remove.


You will now be left with a hole, If the hole isn’t plugged it will spew coolant once fired up. There are companies that make block off’s for it, and Its a common thing to put your coolant temp sensor in there so that you will have a working temp gauge in your cluster. Pat had previously had one on his old motor, so I just swapped it over.


I just put some Honda Bond on the threads to make a complete seal. You can use teflon tape, but the coolant will eventually eat away at the tape, and could potentially become a coolant leak. You will also notice that the plug doesn’t not need to be threaded all the flush, you will feel when its “tight” DO NOT OVER TIGHTEN!


Next you will need to block off the smaller water nipple.


slide a rubber cap over it.


Then use a tiny hose clamp to secure it. Since it is a part of the coolant system it is going to become pressurized, and if not clamped down the rubber cap will blow off under pressure. There is probably a better way to do this (like maybe welding it shut) But this is how I have had it on my own K swap for the last 5 years, with plenty of track time and never once an issue.


Lastly the nipple coming out of the center of the intake manifold where the air idle assist hose would go to. You don’t really need to put a rubber cap on it since there isn’t actually a hole for the air to pass through on the thermal intake gasket. I usually put one on though.


There is no need for a clamp or anything since this sees no vacuum/boost pressure

WOW that was a lot of info. BUT WAIT, there’s more! Let’s move on to installing the EP3 adjustable pulley.


This part was also previously on Pat’s old motor, I just took it off and reinstalled it on the new motor. I like this kit because its very basic, and easy to install. However as I mentioned earlier in this post, the weak link of this kit appears to be the lower quality bearing inside the pulley. I have not personally had an issue with this, and I’ve been using mine for years. But I know pat has had the issue and some other guys as well. I’m going to go ahead and put the Part number/box for the better bearing replacement below.


Simply unbolt the pulley and push the old bearing out, then replace with the new bearing. its a very easy swap.


Above is the OEM power steering pump that you will be removing. Just unbolt the x2 12mm bolts.


Now fit the K-tuned adjustable EP3 pulley. They supply two hex bolts to secure it (they fit countersunk in the bracket, for a clean look) make sure you put loctite on these.


Above you can see how the previous setting he had it adjusted to wasn’t going to be tight enough to run on this motor. Below you can see the notches of adjustability on the bracket.


Loosen the pulley slightly, not enough for the pulley to move up and down too easily. But not so tight that you can’t adjust it.


You will now have to take the tension off the tensioner to get the belt to fit. you do this by putting a socket on the tensioner pulley, and press downward (clockwise) to take the tension off the belt completely so you can route the belt around all the pulleys.


You can see how I moved it up about 4 notches.


To ensure proper adjustment, the arrow on the tensioner bracket must be in the “service window” the square on the tensioner its self.


Above you can see how high the pulley is set, and where it puts the arrow. It’s out of spec, TOO LOOSE.


I now adjusted the pulley to almost the highest notch, and you can see that puts the arrow on the opposite side of the service widow. Meaning this was TOO TIGHT.


I went one notch lower (making it slightly looser) and it puts the arrow just barley in the box (service window). This will have to do because I don’t want it to be too tight and cause any premature wear on any of my pumps, pulleys, or bearings.

Now the motor is starting to look a lot better.



Thanks for taking the time to read the first installment of our K swap Guide series. I know it’s a lot of information to read, but it’s a very good guide for many people to learn about the exact step by step processes. Im pretty sure there is too many pictures on here and its going to cause the page to load a bit slower, but I really wanted to make sure I highlighted very specific things. I would love hear feed back about this post, or help answer any questions you might have about doing a swap. Please, like always don’t hesitate to reach out to me via email at Billy@functiontheory.com, Instagram DM @Functiontheory, or just leave a comment on this post and for sure I will reply to everyone.









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