I have a set of 4 into 1 stainless headers that I want to connect up with an old stainless steel 1in-2out Tangerine muffler. The muffler was obviously not made for this header system but they are not that far off either. Well a little is a lot in this case I guess.

I have a MIG welder and thought I’d buy some self-shielded stainless wire (rather than invest in a whole tank of gas), and try to fix the gap. If nothing else I figured I could tack up a solution and let a real welder finish it (if blowing holes became unavoidable).

I’ve found that the tube exiting the muffler is apparently made up of mild steel at the flange (magnet sticks strongly), then the curved mid-section of the tube is a low carbon steel (magnet sticks BUT NOT strongly), then the very short part is all stainless as is the rest of the muffler (magnet does not stick).

I’m looking for suggestions as to where you guys would cut, maybe good only spots to buy pre-curved stainless or what to search for. General suggestions would be appreciated. Part of wanting to take on this task is that I’d like to add to my welding experience if I can. Here are some pics of the project:

Another view

Another view again

At the header, I’ve actually slid the collector down about 1/2” in these pics so that the flanges would touch. I think there is still plenty primary pipe inside the collector, but is there a minimum I should be concerned with? I could obviously move it back where it was designed to sit, if changing the muffler input area anyway.

Ok there is no way that muffler is stainless as it is rusting in a way stainless doesn’t. Are wanting to modify the header or the muffler? Always cut the straight section never in a bend

I think the muffler inlet was altered by someone else already. Everything but the flange and first few inches is stainless. (I could be wrong. It was made a long time ago.)
It appears that two cuts and two short pieces of tubing would get you where you're trying to go.

cut in 2 places where shown, you have to extend it out away from the muffler, then you need to rotate the flange, so you might as well extend the flange so the collectors are fit in the correct position.

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Right, your suggestions are along the lines of what I’ve been thinking.. only thing though is that I’m gonna need a “small drop down” section (probably just off the muffler) - like a soft “Z” shape, to get to the lower placement of the header flange. Is anything like that even available- or would it need to be made ?

Googling, apparently it’s called an ‘s‘ bend. They look to be much longer than what it appears you need.

Let’s call the cut next to the muffler cut 1 and the one near the flange cut 2.

Seems you could rotate cut 1 to account for the drop, then the extension piece you need to add at cut 2 could be slightly to account for any alignment. This would essentially create the “z’ you mention.

Is it possible to bolt the muffler to the header and use a torch to heat the muffler part to bend it the way you need? Just a thought. Cant weld so no real experience.
Tony

assuming the muffler body is released from it's mounting point... and the flanges are then bolted together - the muffler would then be pointing upwards at about a 45degree angle.

Getting the curved pipe red hot and pushing the muffler downwards to meet it's original mounting locations would probably just twist/collapse the curved pipe in on itself, no? Also, that would likely take more heat than I could build up too (only got a small bottle MAP torch, besides the Mig welder)

I think I'm gonna buy a "U" shape pieces and cut several pieces from it, possibly to include small "pie" cuts for a gradual step down if needed.

Ok well I made the cut at the muffler end of the curved pipe.. and bolted the flanges together

Also drove the collector up to where it’s supposed to sit:

Now I can see the situation better..
if I now make a cut at the muffler’s flange and clock the curved pipe downward just a little bit, the pieces will line up nicely. No need for a “Z/S” shape:

Looks like only a 1/2”- 3/4” filler piece of stainless will be needed to bridge the gap:

I would still make the second cut where infraredcalvin drew it. That will give you more flexibility to make adjustments when you try to align it all together, and it will be easier to weld than right at the flange.

Sorry but I have to ask, are you not defeating the reason for a header in the first place but choking it off at the muffler inlet pipe? Maybe you could knock a piece of wood into the inlet pipe and run a hole saw to get a bigger hole in the muffler and then weld in a pipe that is closer to the diameter of the header outlet? Just curious about the reduction

@Literati914

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I agree that the reduction might be too much

Actually, the inexpensive collector is far from optimized. The pipe going into the flange is way too big. Other than trying to make the reducer smoother, I don't think there's much to be gained by enlarging the muffler inlet.

I think the pics are accentuating the pipe diameter differences more than the reality. I'm getting a consistent 54mm OD at the muffler-in, and throughout ALL of the stainless curved area... and 64mm OD at the muffler flange area AND the header flange are. So that's 2" and 2.5" ... is that an uncommon reduction? I've always heard a little backpressure was a good thing



Chris, can you elaborate on what you mean by "inexpensive collector" and how it could be optimized? I figure that comment was not necessarily a slight on the header unit, but I'm confused by the statement and would like clarity. I can change any/all of it .. and now's a good time for it. So if you have a suggestion, I'd like to hear so I can better consider how I handle it. I thought of scrapping the entire curved muffler pipe and starting over with ALL stainless, but honestly if it equals little to no gain, I don't see the point. Also, I was really trying to keep it simple and not buy a whole bottle of special gas for stainless as it's just a small job (was gonna get some Blue Demon self shielding stainless wire). All thoughts appreciated.

If Chris says it's fine, I'm no expert. I'm thinking flow:

"The first question is at what cfm do we experience 120ft/s in 2" and 2.5" pipe? We calculate the area of the pipe, convert to sq.ft. & seconds to minutes, and after doing the math we find the answers are 157cfm for 2" pipe and 245cfm for 2.5" pipe (the Engineers will find both air flows at Mach 0.11)."

I had this in my head that loosed my fingers. Sorry