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PLM Header - Fab Question

20K views 12 replies 5 participants last post by  IronGumby 
#1 · (Edited)
I have tried many things to get my PLM header to make a good seal at the donut gasket. The compressed tinfoil gasket that came with it was a piece of shit and I threw it away. Seriously it looks PLM got a good deal on aluminum foil and pressed it into a mold. LOL.
I purchased a Vibrant Gasket but the I.D. of it was larger than the outside diameter of the header. I was able to make it fit well by using a pipe clamp that I cut the screw mechanism off of -and using the thin band of metal to 'sleeve' the donut gasket...

I still do not have a good seal at that connection.

I would like to purchase a flex joint as well as a high flow cat, because I really do not like having a cat on my car. I figure this will eliminate the annoying ticking sound of exhaust escaping the connection as well as my breathing exhaust fumes every time I come to a stop light, its just unhealthy.

I was thinking of buying a 2.5" x 4" flex joint from vibrant. Once again the ID of it is 2.5" which I think will be slightly larger than that of the OD of the header.

I was thinking about buying a tail pipe expander and expanding the pipe to match the diameter. Either that or I was thinking I would slip the flex joint over where the current donut gasket goes and weld it to the flange that is already there. I would then weld the high flow cat to the flex joint and see what needs to be done to get a good fit with the cat back.

Basically what I am wondering is would a 4" flex be good or should I go longer?

What will be the best way of welding this together? I have access to a MIG welder and was planning on using that.

I also want to add a hanger to the header to utilize the stock hanging location to help with the added weight of the cat. I see a lot of SSR headers and others using the stock location to 'hang' the header on.

Any guidance or suggestions regarding this would be great. I plan on doing this in a few weeks and wanted to gather information and materials before.
 
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#3 ·
Thanks man. I'll have to look into welding a little more haven't really done too much research on that yet. Watched a video or two on youtube...

I am particularly interested in the joint where the flex pipe meets the header-as most of the flex pipe I have looked at is 2.5" inside diameter and I know the header's outside diameter is just shy of 2.5". What have people found to have worked here.

schwannman did you put a vband on the header to connect with whatever you connected it to?

Also while I am going to have to make some more measurements.... I was playing with the idea of taking the bend out of where the catback meets the header.
 
#6 · (Edited)
jamesandrew58, that looks nice. I really like the V-band connectors but damn $70 each? For a stainless flange? Why so expensive? Doesn't really seem like there is a whole lot there... How did you clean up the flange ports? I am assuming you port matched them to the head so to speak.... what did you use to make your measurements etc....

Also how was the fitment of the 2.5" - 3.0" transition. It looks really nice on the outside but slightly weird from the inside shot, I can't really tell whats going on though?

Also I just found out that my friend who has the MIG welder also has a TIG welder so I have access to both. Which would you recommend using?
 
#7 ·
A v-band is expensive because it needs to be precision machined in order to have a gasket free seal. I like Vibrant's v-bands over others because it has a unique "male/female" design to ensure proper alignment of the flanges inside the clamp. Along with that, each flange has a step where the pipe sits on for easy alignment when welding. You could simply use a normal 2/3 bolt flange if you wanna keep costs down. I used a die grinder with sanding drums to clean up the ports. All I wanted to do was remove the lip that was caused from welding the flange to the pipe. Not really a port match, and no measurements were taken. The transition fit nicely, very smooth on the inside. I would use the TIG if you can.
 
#8 · (Edited)
Ok.
I am scrapping the idea of putting a cat on for now. I will do that at a later point, just trying to keep cost down right now.

So here is what I am thinking:



To explain the drawing:
I am hoping to reuse both the 2.5" 2 bolt flanges that came with the header, so that I only have to buy 2 more 2.5" 2 bolt flanges (and gaskets) + flex pipe. I will keep the one that is on the header in its existing location and just cut off the extension of tube for where the existing donut gasket would sit.
I would then weld the new 2.5" Flanges to both sides of the flex pipe.
Bolt the flex pipe to the header.
Mark length that test pipe needs to be. Cut the test pipe.
Then I would use the existing flange on the test pipe (the loose one that slides) Weld it to the test pipe and have it bolt to the other side of the flex pipe.

Potential down falls? Oversights? Or a reason why I would not want to do it this way?

The reason I want to have the flex pipe have two flanges on it is to make adding a cat on easier at a later date.

If it is possible to do this way to total cost is ~$100. I def don't want to spend more than that.

I am also thinking about cleaning up the welds like jamesandrew did.. I do not have a die grinder, was thinking maybe using a carbide burr with my dremel? idk...
 
#9 · (Edited)
The only thing I would recommend is adding pipe between the flange and flex. The flex will slip onto the pipe making the connection stronger vs. welding the flex directly to the flange. In the picture below, the pipe slips into the flex where you see the red dotted line. As for cleaning up the flange ports, a Dremel can be used, but it may burn it out.

 
#10 ·
The only thing I would recommend is adding pipe between the flange and flex. The flex will slip onto the pipe making the connection stronger vs. welding the flex directly to the flange. In the picture below, the pipe slips into the flex where you see the red dotted line. As for cleaning up the flange ports, a Dremel can be used, but it may burn it out.
Thanks for the suggestion about adding a bit of pipe to the flex couple. I will definitely have to do that when I do this in a couple weeks. Ill post pics up of how it comes out and such.
 
#13 ·
Hey mtnbike42, any successful results? I am looking to get a hi-flow cat pipe to swap in place of my test pipe, mainly to eradicate the smell at stoplights. However, I am not convinced this will do the trick if my donut gasket is still leaking (I just assume it is because the smell is like instant -- not enough time to travel from the tailpipe to the air vents). So I'm wondering what else I can have an exhaust shop do while they're in there. Is getting the slip-joints welded a must-do as well? And is having the 2.5" transition immediately to stock catback (2.1"?) handled a better way than via the 3-bolt flange? I didn't want to mod anything because I wasn't sure if I'd sell the header or catback at some point down the road so that could be leaking too? Sorry, possible exhaust noob status here :laughat:
 
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