Hi folks – hope everybody had a decent weekend. I have a set of very end very nicely made headers that I ordered for Marty for my big Type4 build. I didn’t realize in this is completely my responsibility end that they would come with a center exhaust collector because I had planned to use them with a 911 muffler. So I either need a different before design or to make some sort of connectors.

Has anyone been down this path that could weigh in on suggestions and any clever ideas that they’ve used or seen?

Again I want to stress that these are very nicely made and I’ve had nothing but a good experience with Marty on other things I’ve ordered with him. I didn’t sweat the details and what I received is in no way shape or form less than an excellent product.

Thanks!

I was looking at his headers yesterday, was wondering if I could make something to adapt mine. What I came up with is I'd need something like a 911 muffler. I'd have to know how it was constructed, maybe someone here who knows can jump in. I thought it can still hang off the trans with a better mount, and I could plug the holes on the side of the muffler and run a bigger tube straight in from the header to the back center of the muffler. Worst cast I'd need to open the muffler and do a bit of plumbing.

Not knowing what was inside design of the 911 muffler I was planning on slightly different path – so this week end of leaving the muffler ports where they are and fabricating connectors from the termination of Marty’s central collector to where the 911 ports are.

Any points or street cred for the run on sentence above?

Thanks for jumping in, let’s see if we can collectively figure this out. I’m sure it’s clear, but just to be super duper clear, Marty makes great stuff and I am extremely happy with everything I’ve bought from him.

This probably won’t help any but I’ve got the same sort of situation planned for a 2.1L hour ngoni that I have. The muffler, I believe is early Tangerine 911, think this is how it was advertised .. purchased used obviously. The muffler apparently attaches directly to the two bolts at the back of the 901 transmission (though I have no idea if this is going to work w/ a 914).

Muffler is stainless btw. In this picture you can see that the flange junction is oh so close to being right, despite the header and muffler not being made for each other. But close, might as well be a mile off I guess. I was thinking of cutting off the flange end of the muffler (cut it back close to the muffler body and weld on another flange). Then add a braided style flexible stainless intermediary piece:


.

Interesting solution, but that can be made to work.

Yea if I could get some properly sized stainless tubing and someone with the skills to weld stainless to stop by (I’ve not delved into welding stainless yet), I could come up with a more permanent solution. But the item below (as an example) is the type of thing that could work too, with the flanges welded on.

BTW - I assume this will be loud, so I’ve thought of adding the silencer INSERTS that are made for motorcycle exhaust tips.

Is there any flex to that?

Wonder if we both need to go to a custom muffler shop with a box of donuts in hand...

My assumption was that yes they flex..but now that you’ve asked the question , hmm I really don’t know.

My problem with taking this stuff to a shop, is that I’d need both the engine & transmission to be present as well as upside-down (like I already have it). That’d be a pain, so I’d rather pay a decent welder with the equipment, experience and ability - to do the work at my place…if I can find someone willing


.

Any pictures of Marty’s headers?

Been thinking down that line of using a ‘80s? 911 banana muffler 1in -1out connected to 4 into 1 headers. Muffler could be attached to the gearbox using a bracket and two classic straps. I believe mb911 was making similar brackets. Having a flex between the headers and muffler would allow for thermal expansion.

Maybe the pros will chime in...

No flex, it's bolted solid to the engine/trans. The engine/trans mounts absorb the vibrations and is how it's's isolated. It's when you try to hang the muffler off of the body that you'll run into big problems.
From the lowly VW 25hp to today's Porsche rear engine cars that's how they all roll.

For Literati, I think this is pretty simple.
Cut the muffler along the weld lines in red.
Click to view attachment

1) Rotate the flange, add the correct gasket, and bolt it to your headers. THEN weld the pipes to the flange using the headers as a jig. Couple tacks will do to hold it in place for phase 2.

2) Add however much pipe it takes to mate the newly welded muffler intake flange to the muffler proper. I'm guessing about an inch would do it. Again, you want the muffler bolted to the transmission and the flange pipe bolted to the headers with the gasket in place. This is your jig. Couple of tacks and you can unbolt everything and make your welds proper.

Easy easy fix!

Zach

I was thinking that as well. One other concern would be determining the correct height of the muffler outlets relative to the car body, bumper and rear valence. May be kind of tricky without the engine/tranny mounted in the car.

With the muffler bolted directly to the tranny case, I expect thermal expansion is going to stress your muffler mounting flange ultimately causing fatigue cracks & failure.
If you can arrange a flex adapter you can then get the muffler to line up & have the necessary flexibility to overcome differential expansion between engine/tranny cases & exhaust header.
That's why the standard muffler hanger is long & flexy fore & aft.

Something about that muffler looks vaguely familiar, but the inlet pipe has been modified.
Don't remember the car it was built for but certainly was not 911. Had to be a one-off, and very early.
Zach's solution seems like the best.