2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Give me your opinions on my manifold porting

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Old Jun 27, 2004 | 07:30 PM
  #1  
ddub's Avatar
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From: Kirkland, WA
Thumbs up Give me your opinions on my manifold porting

Alright, so after breaking a stud on my LIM and having all around problems with it, I pulled everything to do some work. While it was out I figured I might as well go back and fix my previous port jobs on my manifolds, because the first time I had to do a quick and somewhat sloppy job and didn't go as big as I could have in some parts. So here are some pics of the porting I did to the UIM, give me your opinions. How does it look? Did I do anything noticeably wrong? Should I go bigger anywhere? Or any other comments would be great.

First, here are the ports that connect to the dynamic chamber. In the archived how-to it said not to worry about these because they were already the same size as the gasket, so the first time I ignored them. But looking at them I realized the big ledge/bump thing in the beginning could be grinded all the way down and made into a smoother transition into the intake passage. So here's the pics of what I did:







Alright so then I went on to the other side of the UIM to redo and fix some of the porting I did before. I did them as described in the how-to in the archive, but let me know if you think I should/can go bigger anywhere. When looking at the pics closer it seems like I could grind a little more away on the outisde ports on the outer parts of them, making it a better transition. But when I reach in there and feel it, it seems like the walls are getting close to the *too* thin range, so I wasn't sure. Let me know what you think:





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Old Jun 27, 2004 | 08:12 PM
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DEZERTE's Avatar
777** The Anti-rice
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From: Seattle, WA
**** dude, you ported a lot. I didnt port that much. looks good though! Cleaner out real good
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Old Jun 27, 2004 | 08:16 PM
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ddub's Avatar
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Originally posted by DEZERTE
**** dude, you ported a lot. I didnt port that much. looks good though! Cleaner out real good

Heh, yah I went as big as I possibly could, or at least I thought I could. It seems like I could go even bigger (a little bit in some spots) but its getting harder to do and I'm getting more nervous

Yah I'm going to clean it up real good, those pics were taken just after I got done.
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Old Jun 27, 2004 | 10:37 PM
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ddub's Avatar
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From: Kirkland, WA
Bump...

Any more opinions out there? If you think I can go bigger I'd like to know, as I'm just not sure.
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Old Jun 27, 2004 | 10:54 PM
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i dunno man but u did port the crap out of them looking good. i wouldnt do any more. might get to hot and melt or somthing....
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Old Jun 27, 2004 | 11:09 PM
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DEZERTE's Avatar
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Originally posted by KingCobraV9
might get to hot and melt or somthing....
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Old Jun 27, 2004 | 11:20 PM
  #7  
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From: fl
well you can go to big. remeber the whole point of porting is to make the path for the air as smooth, short, and consistent as possible. thats some very aggresive porting, especialy on the upper/dynamic chamber. make sure that the transitions from the parts you port to the stuff you cant reach remain smooth and consistent.

also, creating a big buble or area of significatly larger cross section will not help very much if it has to narrow back down again.

on my s5 i was more aggresive o the middle/lower interface, made it more "egg shaped" but i think the angles of the runners on the vdi manifold justified cutting into that corber more to shorten the path.

im not as familiar with the s4 n/a manis as the s5, bu i think you may have crossed beyond the line where porting is usefull (at least on the upper/middle interface). mite not loose performance, but it might not help as much as it could have.

my .02

Last edited by andrew lohaus; Jun 27, 2004 at 11:25 PM.
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Old Jun 27, 2004 | 11:31 PM
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ddub's Avatar
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From: Kirkland, WA
The how-to in the archive stated to make the outer ports that connect to the LIM from the UIM egg-shaped and the inner ports merely port matched to the gasket. I did this, but I made the "egg shape" as big as I could. I don't really see how this could be a bad thing. The passage from those ports has been smoothed out as far down as I could, and the bend that continues into the rest of the runner was also ported as much as possible to make the transition smoother. The ports on top that connect to the dynamic chamber were not make any bigger on the outside (ie they are still the same size as the gasket). Stock, these top ports have little bump/ledge things inside the runner; what I did was grind those away to be a more complete and smooth transition from port hole to the runners (no more bump/ledges).

I made the ports as smooth and consistent as I could as far down as I could reach with my dremel. What do you mean by the air has to travel farther now? I don't really understand. Which ports are you refering to?

By bubble are you referring to the egg-shaped ports on the outside? If so, the ports on my LIM are going to be matched to those, for a smooth transition, and I realize that it will have to narrow back down some before going into the block, but the ports on the other side (going to the block) will be port matched to the gasket once I'm done, so it'll be as good as I can get it.
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Old Jun 28, 2004 | 12:18 AM
  #9  
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That looks great.

I was experimenting earlier:
(4th photo)
http://jhillyerrx7club.tripod.com/

This will probably show Tripod's annoying offsite banner:
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Old Jun 28, 2004 | 12:24 AM
  #10  
ddub's Avatar
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i am legendary
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From: Kirkland, WA
Yep, banner showed up

Looks good, I'll be doing my LIM soon.
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