(click on photos for larger versions)
It really bothered me that I had my throttle body bored out, but that my intake manifolds were still in stock condition. Unfortunately I cannot have my car down long enough to send my manifolds to TK and I did not really want to spend $300 on that. But, with the SFR tuning event coming up, I wanted to make sure I got the most out of it so I decided to go ahead and do some work myself.
As you know, the V6 manifolds flow unevenly having less flow on the passenger side as compared to the driver side which causes issues. Search the forums for more info on that.
Let me just say that it's no wonder the flow rates vary so much. I really think Hyundai did a sloppy job and should address this. I found a lot of extra material on the passenger ports and some of the ports were misshapen.
My goals:
1. Investigate the condition of the manifolds and ports to see what might be causing the low flow and identify any low hanging fruit that I could address
2. Clean up any poor casting problems
3. Gasket match as best as I can
4. Remove any material I can safely
Note: The photos I took do not do the work I did any justice. I wish I had taken better photos, but myself, my phone and my work area was covered in aluminum shavings so it wasn't a top priority.
Overall I think I did a pretty good job. I'm pretty happy with the work I did. It only took me about 3 hours including taking a shower after being covered in aluminum. I may have not done as nice of a job as TK might have done and I did not do any flow tests to support the work I did do, but the results were noticeable as I'll describe at the end.
I already had a dremel and the extension to go with it. I just picked up some additional bits for it before starting

pulling the manifolds off was fairly simple. After getting them off I inspected them. Here is what I found
Bottom of lower manifold

This is the driver side of the lower intake manifold where it mates to the head. It's odd that 1) the gasket was screwed to the manifold 2) only the driver side was screwed on...
As you can see the gaskets are fairly matched to the lower portion so I decided not to do a whole lot on the bottom. I did notice there was a slight lip on the edges so what I did was use a flat file to clean the edges and a round file to do the same for the rounded edges. I then ran through each port with a 60 grit sanding wheel to smooth out some of the rough surfaces and address the bumps that sit in the path of the passenger side ports (see the next section) followed up by a 120 grit flapper wheel to clean up and smooth out the worked areas.
Sorry, I did not take an after picture of this. The work was minimal though.
Top of lower manifold

This is the top and as you can see, the ports don't match up to the gasket very well at all, especially on the passenger side ports (top ports).

A closer look at how much they don't match up. On the lower intake, the gasket doesn't move around at all so this isn't simply a gasket positioning issue. See how much different the top ports (passenger side) look from the bottom ports (driver side)? Notice in the top ports (passenger side) there are bumps. The manifold is actually cast this way. I imagine for clearance? But I'm not sure for what. Grinding these down may cause a weak spot in the manifold so I only did minimal work on them.
This was really fun. I used a pencil to outline the areas I needed to work on and then removed the gasket and got to work. I started with the aluminum oxide cutting but which was cone shaped to help do the blending. There is a cylindrical version but I don't recommend that one as it's too easy to cut into areas you don't want to cut into.
I started out by working the edges. I removed as much material as I could according to my markings. When I was down as far as I could go, I started working inward on the material. I took out what was necessary to 1) match the contours of the port design and 2) match it up to the outer edges that I just opened up.
I made sure to blend the areas as I went, not cutting out too much in one section at any given time. When I was happy with where the ports were, I switched to the 60 grit wheel and went over the worked areas to clean them up, smooth out any scars I may have left and try to shape the contours more. I also removed some of the rough casting as far into the port as I could, but this was not one of my goals so it was basically just a quick clean up job. I also removed a little more material as needed. Once I was done with the 60 grit wheel I switched to the flapper wheel and smoothed everything out.
I really like the flapper wheel. The one I got fit perfectly into the ports which made cleaning up the curved areas super easy.
Here is the finished result. Again, the photos don't do the work justice.

In this photo the driver side is on the top and the passenger side is on the bottom.
Bottom of upper intake

This is where the crappy port shapes were. If you look at the top right port you can see how bad it is. The top row on this photo is the passenger side. The gasket on the upper moves around a lot so getting it positioned correctly was hard. This photo doesn't show it, but there is actually a lot more material to remove from the top of the passenger ports (top row).
Same process as before, I tried to align the gasket as best I could, trace the areas that needed work and got to it. I did the same work as I did for the lower intake, but I did it in several iterations since the gasket moved around. I looked at the ports while moving the gasket around so I could see how it might affect it when it was reinstalled. I removed enough so that enough material was removed that the gasket did not overlap the port no matter where it was positioned.
In the upper manifold the passenger ports have a much sharper curve to them so I spent time trying to open up the bend and smooth it out.

Each of the ports I did has a very nice, clean transition along the contours and there are no rough gouges or scratches, but it isn't mirror smooth either.
The misshaped port really bothered me. If I accomplished nothing else by doing this work, I at least cleaned up those nasty problems.
Mouth of the upper intake
I didn't take any pictures of this, but I did notice the mouth of the upper intake where the throttle body sits did have a very tiny lip, so I pulled it off and cleaned up up. While I was in there I noticed it had some nasty casting marks which I cleaned up and it also had a lip that I smoothed out which looked like it could cause airflow to be redirected upward to the driver side ports away from the passenger side ports. Was it really doing that? I have no clue but I smoothed it out anyway. There was also another bump on the top of the mouth which I cleaned up.
I only did this because I have a bored TB. Stock TB won't matter.
Also note that in these photos the ports look dark and there are uneven areas as far as where I worked (swirl marks, etc). This is actually because I didn't wipe the ports down with a towel. After I did that, they were much cleaner and nicer looking.
Results
There is no way to tell what effects the work I did had on the car because I've done other things without doing a dyno in between. So all I have to go on is butt dyno.
First off, when I started it up I noticed it had a deeper intake noise. Throatier for sure. That's an indication I made some kind of impact. On the throttle I have a much raspier intake noise which I don't mind at all
Performance wise I did notice a big improvement. 3k-5k is much snappier. Throttle response overall is better and in all ranges it feels like it's pulling harder. I was in 3rd around 4k and punched it. I felt the tires let go and then TC came on to save me.
Last night on our way home, my wife and I were driving together in our cars. When we do that of course we have fun. Normally from a roll (I get killed from a dig) she will pull away hard for a few cars lengths but I eventually over take her on the top end. This time the distance in which she was able to pull away from me was much smaller.
This is purely anecdotal and is in no way scientific, but my observations none-the-less.
Conclusion
The work itself was simple. I took my time and thanks to the coned cutting bit being small and having small teeth, the small mistakes I made from going too fast or having shaky hands did not cause any damage.
This was a pretty simple task and I'm really happy I did it. I spent $45 to get some extra dremel bits but I would have gotten them anyway.
Again, I don't know if I actually improved the flow, increased the potential CFM or just caused a flat powerband, but the car feels great and seems to like it.
Tips for doing this yourself
1. Wear eye glasses
2. Wear a mask. I started with a mask but it kept fogging up my glasses so I took it off and had black snot to deal with
3. Go slow, take your time and eat away small amounts of material at a time
4. Always be moving the bit, don't sit in one spot
5. I'd recommend getting a 60-grit flapper wheel in addition to the 120-grit flapper wheel and use those instead of the sanding wheel. I think it would work much better, covering more surface area at one time and allowing you to get both the top and bottom of the ports at the same time and work on the curves better. Do have sanding wheels on hand though just in case.
6. Put the dremel on highest RPM and use a light touch. It's much better results and safer than slower speed with harder pressure. You have more of a chance of causing gouges or breaking your bit with more pressure.
It really bothered me that I had my throttle body bored out, but that my intake manifolds were still in stock condition. Unfortunately I cannot have my car down long enough to send my manifolds to TK and I did not really want to spend $300 on that. But, with the SFR tuning event coming up, I wanted to make sure I got the most out of it so I decided to go ahead and do some work myself.
As you know, the V6 manifolds flow unevenly having less flow on the passenger side as compared to the driver side which causes issues. Search the forums for more info on that.
Let me just say that it's no wonder the flow rates vary so much. I really think Hyundai did a sloppy job and should address this. I found a lot of extra material on the passenger ports and some of the ports were misshapen.
My goals:
1. Investigate the condition of the manifolds and ports to see what might be causing the low flow and identify any low hanging fruit that I could address
2. Clean up any poor casting problems
3. Gasket match as best as I can
4. Remove any material I can safely
Note: The photos I took do not do the work I did any justice. I wish I had taken better photos, but myself, my phone and my work area was covered in aluminum shavings so it wasn't a top priority.
Overall I think I did a pretty good job. I'm pretty happy with the work I did. It only took me about 3 hours including taking a shower after being covered in aluminum. I may have not done as nice of a job as TK might have done and I did not do any flow tests to support the work I did do, but the results were noticeable as I'll describe at the end.
I already had a dremel and the extension to go with it. I just picked up some additional bits for it before starting

pulling the manifolds off was fairly simple. After getting them off I inspected them. Here is what I found
Bottom of lower manifold

This is the driver side of the lower intake manifold where it mates to the head. It's odd that 1) the gasket was screwed to the manifold 2) only the driver side was screwed on...
As you can see the gaskets are fairly matched to the lower portion so I decided not to do a whole lot on the bottom. I did notice there was a slight lip on the edges so what I did was use a flat file to clean the edges and a round file to do the same for the rounded edges. I then ran through each port with a 60 grit sanding wheel to smooth out some of the rough surfaces and address the bumps that sit in the path of the passenger side ports (see the next section) followed up by a 120 grit flapper wheel to clean up and smooth out the worked areas.
Sorry, I did not take an after picture of this. The work was minimal though.
Top of lower manifold

This is the top and as you can see, the ports don't match up to the gasket very well at all, especially on the passenger side ports (top ports).

A closer look at how much they don't match up. On the lower intake, the gasket doesn't move around at all so this isn't simply a gasket positioning issue. See how much different the top ports (passenger side) look from the bottom ports (driver side)? Notice in the top ports (passenger side) there are bumps. The manifold is actually cast this way. I imagine for clearance? But I'm not sure for what. Grinding these down may cause a weak spot in the manifold so I only did minimal work on them.
This was really fun. I used a pencil to outline the areas I needed to work on and then removed the gasket and got to work. I started with the aluminum oxide cutting but which was cone shaped to help do the blending. There is a cylindrical version but I don't recommend that one as it's too easy to cut into areas you don't want to cut into.
I started out by working the edges. I removed as much material as I could according to my markings. When I was down as far as I could go, I started working inward on the material. I took out what was necessary to 1) match the contours of the port design and 2) match it up to the outer edges that I just opened up.
I made sure to blend the areas as I went, not cutting out too much in one section at any given time. When I was happy with where the ports were, I switched to the 60 grit wheel and went over the worked areas to clean them up, smooth out any scars I may have left and try to shape the contours more. I also removed some of the rough casting as far into the port as I could, but this was not one of my goals so it was basically just a quick clean up job. I also removed a little more material as needed. Once I was done with the 60 grit wheel I switched to the flapper wheel and smoothed everything out.
I really like the flapper wheel. The one I got fit perfectly into the ports which made cleaning up the curved areas super easy.
Here is the finished result. Again, the photos don't do the work justice.

In this photo the driver side is on the top and the passenger side is on the bottom.
Bottom of upper intake

This is where the crappy port shapes were. If you look at the top right port you can see how bad it is. The top row on this photo is the passenger side. The gasket on the upper moves around a lot so getting it positioned correctly was hard. This photo doesn't show it, but there is actually a lot more material to remove from the top of the passenger ports (top row).
Same process as before, I tried to align the gasket as best I could, trace the areas that needed work and got to it. I did the same work as I did for the lower intake, but I did it in several iterations since the gasket moved around. I looked at the ports while moving the gasket around so I could see how it might affect it when it was reinstalled. I removed enough so that enough material was removed that the gasket did not overlap the port no matter where it was positioned.
In the upper manifold the passenger ports have a much sharper curve to them so I spent time trying to open up the bend and smooth it out.

Each of the ports I did has a very nice, clean transition along the contours and there are no rough gouges or scratches, but it isn't mirror smooth either.
The misshaped port really bothered me. If I accomplished nothing else by doing this work, I at least cleaned up those nasty problems.
Mouth of the upper intake
I didn't take any pictures of this, but I did notice the mouth of the upper intake where the throttle body sits did have a very tiny lip, so I pulled it off and cleaned up up. While I was in there I noticed it had some nasty casting marks which I cleaned up and it also had a lip that I smoothed out which looked like it could cause airflow to be redirected upward to the driver side ports away from the passenger side ports. Was it really doing that? I have no clue but I smoothed it out anyway. There was also another bump on the top of the mouth which I cleaned up.
I only did this because I have a bored TB. Stock TB won't matter.
Also note that in these photos the ports look dark and there are uneven areas as far as where I worked (swirl marks, etc). This is actually because I didn't wipe the ports down with a towel. After I did that, they were much cleaner and nicer looking.
Results
There is no way to tell what effects the work I did had on the car because I've done other things without doing a dyno in between. So all I have to go on is butt dyno.
First off, when I started it up I noticed it had a deeper intake noise. Throatier for sure. That's an indication I made some kind of impact. On the throttle I have a much raspier intake noise which I don't mind at all
Performance wise I did notice a big improvement. 3k-5k is much snappier. Throttle response overall is better and in all ranges it feels like it's pulling harder. I was in 3rd around 4k and punched it. I felt the tires let go and then TC came on to save me.
Last night on our way home, my wife and I were driving together in our cars. When we do that of course we have fun. Normally from a roll (I get killed from a dig) she will pull away hard for a few cars lengths but I eventually over take her on the top end. This time the distance in which she was able to pull away from me was much smaller.
This is purely anecdotal and is in no way scientific, but my observations none-the-less.
Conclusion
The work itself was simple. I took my time and thanks to the coned cutting bit being small and having small teeth, the small mistakes I made from going too fast or having shaky hands did not cause any damage.
This was a pretty simple task and I'm really happy I did it. I spent $45 to get some extra dremel bits but I would have gotten them anyway.
Again, I don't know if I actually improved the flow, increased the potential CFM or just caused a flat powerband, but the car feels great and seems to like it.
Tips for doing this yourself
1. Wear eye glasses
2. Wear a mask. I started with a mask but it kept fogging up my glasses so I took it off and had black snot to deal with
3. Go slow, take your time and eat away small amounts of material at a time
4. Always be moving the bit, don't sit in one spot
5. I'd recommend getting a 60-grit flapper wheel in addition to the 120-grit flapper wheel and use those instead of the sanding wheel. I think it would work much better, covering more surface area at one time and allowing you to get both the top and bottom of the ports at the same time and work on the curves better. Do have sanding wheels on hand though just in case.
6. Put the dremel on highest RPM and use a light touch. It's much better results and safer than slower speed with harder pressure. You have more of a chance of causing gouges or breaking your bit with more pressure.