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Discussion Starter #1
Hi, Im just curious how to port our RBC intake manifold. Here are few questions. As you guys know, there are one inlet and four oulter holes in manifold. People usually grind and enlarge oulet holes smoothing out and line up with intake manifold gasket porifile and head inlet. But, what im curious is if outlet of our stock intake manif and inlet of head are already lined up with gasket, do we really need to port it? I didnt take it apart and took a look at it. so Im wondered about it. And, is it better to port the inlet of manifold to 65 or 66mm in conditions that outlet of throttle body is matched?

Thanks in advance:dance:
 

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Seems like you are referring to two different things as one. There is such a thing as port matching...

If your throttle body is larger then the TB opening on the IM, it is helpful to match the opening on the IM
 

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I mean the first question was only about matching the oulet of manifold and inlet of head on our motor. my question is do we really need to port and polish intake manifld if the oulet of manifold and inlet of head and gasket are already lined up and precisely matched?
 

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You're only seeing the glass half full. What one is trying to achieve by porting is removing rough cast metal inside the intake manifold to smooth out airflow before it enters the head. The only way to achieve that is to cut open the intake manifold which leaves a beautiful(sarcastic) frankenstein looking scar from the weld when it's put back together.
 

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The only way to achieve that is to cut open the intake manifold which leaves a beautiful(sarcastic) frankenstein looking scar from the weld when it's put back together.
while cutting the intake manifold is the easiest way to port the plenum, if you get creative with some stone mandrels you can do a damn good job without cutting the intake manifold apart. it was a little easier for me than it would be for most since i am a machinist with access to a full machine shop, but when i ported my intake manifold i cut the flex shaft off of a couple of used and abused ball hones and turned some adapters on the lathe so that i could attach the flex shaft to a solid stone mandrel. this combined with making some solid extensions, allowed me to get into all the corners and hard to reach spots in the intake manifold and get rid of all the casting imperfections. i followed that up by some sanding mandrels and some regular ball hones and everything came out nice and smooth. get creative and have fun with it :)
 

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Discussion Starter #6
:dance:
while cutting the intake manifold is the easiest way to port the plenum, if you get creative with some stone mandrels you can do a damn good job without cutting the intake manifold apart. it was a little easier for me than it would be for most since i am a machinist with access to a full machine shop, but when i ported my intake manifold i cut the flex shaft off of a couple of used and abused ball hones and turned some adapters on the lathe so that i could attach the flex shaft to a solid stone mandrel. this combined with making some solid extensions, allowed me to get into all the corners and hard to reach spots in the intake manifold and get rid of all the casting imperfections. i followed that up by some sanding mandrels and some regular ball hones and everything came out nice and smooth. get creative and have fun with it :)
hmm..thats interesting to make a creative with some mandrels. May I ask hows ur creative tools look alike with some pictures? Thanks in advance~
 

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Op here is a picture of mine to give you an idea of what a port job would look like.


No offence to the previous poster but i'm not sure how you could compare a job like this versus a creative stone mandrels job. I think accessibility plays an important role here. You want to get the right amount of air flowing through the plenum. the picture is self explanatory
 
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