Customizing my MSA flanged exhaust

[Arne]

Parts are all here (mostly). I can now start the fab work.

Here you can see the mandrel-bent 2¼" 90° elbow that will be used in place of the final bend in the S-pipe. I bought a Cherry Bomb brand #52015 that has a 4" radius. Knowing what I know now, if I were ordering today, I would use a Hedman #12016 which has a slighter tighter bend radius of 3 3/8". Since the room for the muffler and tips is tight, the slightly tighter radius would give just a touch more wiggle room in fitment.

Here is the muffler with tips in final position. In this pic, the tips are only held in place with one screw/rivnut apiece. For the final assembly, I plan to use at least two, maybe three screws per tip. Each screw will have a lock washer at least, still debating Loc-tite.

As I noted above, getting that long muffler/tip assembly under the back w/o having the tips extend too far beyond the bumper will take some fiddling, but I'm pretty certain it's going to work. It's too bad that there aren't any tips in the 7-8" range, rather than the 9" of these. But since the whole idea here was to do this with off the shelf parts, I make do with what I can get.

[Arne]

More details.

The tips need 3 screws each. Two won't locate them firmly enough.

Doesn't look like I identified the muffler yet in this thread - it's a Magnaflow 11148, natural stainless, small 3½x7x14 oval case, 2¼" centered inlet, dual 2" outlets on 2¾" center spacing.

The tips are Hedman 17120, 2" ID inlet but expanded to fit OVER the 2" ID outlets of the muffler. Very little expansion was needed - these tips were designed to be welded, and were a pretty sloppy fit on a 2" pipe out of the box. The actual ID was probably around 2 1/16" or so. So expanding them to fit over the muffler outlets was not much of a stretch.

To get these 9" tips to work, the lower tip has to be butted up tight against the weld of the lower outlet to the case. To make that happen, I had to shorten the lower outlet by about ½", otherwise the tip bottomed out about 10mm short of the weld.

The upper tip is mounted just about 1¼" farther out than the lower. The Magnaflow muffler has outlets that are a bit longer than I expected, which was good - had they been much shorter I could not have bolted the upper tip, would have been forced to weld it.

Edited June 30, 2011 by Arne

[steve91tt]

Great work Arne. Thanks for documenting this.

[Arne]

Yes, for those of you who notice such things (like me), the Magnaflow logo is upside-down. Yes, I know that. Yes, I care. But no, it was not an accident.

While I would have preferred the logo to be right-side up (having more than a touch of OCD), I noticed that the inlet tube on the muffler is angled a bit to one side. Not much, just a couple of degrees. Definitely not intentional on Magnaflow's part, just manufacturing tolerances. But it is enough that I felt the fit would be better if I mounted the muffler with logo upside-down. So that's how it will be. The planned black paint will pretty much hide that anyway.

**********

I picked up the last of what I need (I think) this morning on my way to work. Will finish fitting the tips tonight after work, and probably paint the muffler. I've got tomorrow off, so I expect to complete the whole system early tomorrow, barring something unforeseen.

Edited July 1, 2011 by Arne

[Arne]

Finished the tip mounting tonight. Three rivnuts per tip. Works great.

Then dropped the old exhaust, all one piece save for the Monza tips at the rear.

Cut the rear S-pipe, and started trimming the new 2¼" bend to fit instead. No particular problems here.

Finally, I started bolting up the new, nothing totally tight, but in place to see how it fits. And the rear section is too long. I'm going to be forced to shorten it. The Magnaflow will sit too far back, plus the center hanger is actually 1½-2" too far back as well. I'm thinking about taking a couple of inches out as shown in the picture below. Didn't want to cut there, but I don't think I'm going to have much choice.

[pbarcher]

Over 25 years ago I installed the MSA "turbo" exhaust on my '73, and thought that the sound level was fine. When the muffler finally rusted I replaced the exhaust with the new system from MSA which seemed identical. Maybe I'm just old, but the new muffler was just too loud, so I had my shop, Autoexpectations, install the stainless bullet shown in the photos. They did a great job tucking it out of harm's way, and there was no decrease in performance. It's much quieter now, and more fun to drive.

Peter

[240260280z]

I concur. If MSA wants to raise the bar a low loss glass pack should be included with their kit.

The darn pipe is too long and howls at 2800rpm due to resonance of tube principals.

Here is my experience with a droning MsA turbo exhaust : http://atlanticz.ca/zclub/techtips/exhaust/index.html

[Arne]

Making progress today, but I don't know that I'm going to be happy at the end. I'm far enough along that I'm pretty certain it's all going to fit, but also far enough along that I can say that had I known what I know now, I would not have done it, and would not recommend this project to others.

I shortened the rear pipe 1¾" between the flange and the center hanger. That seems to have worked fine. Allows more room in back for the muffler to fit better, lines up the center hanger with the mount on the diff crossmember, but still clears the rear suspension and diff mounts at the bend. So that turned out OK. Not sure why I needed to do this, as the Magnaflow is the same case length as the Dynomax. The mis-placement of the center hanger is odd too, as that placement would have been wrong regardless of muffler used.

However -- after starting the engine for a quick test, I'm rather fearful that it is going to be louder than I prefer. And Walter was correct, it's going to be darn hard to put a glasspack in the center, as the center pipe is designed to hug the left side of the tunnel very closely.

The loudness might not be quite as bad as I fear, part of the noise is from leaks. The joints where I reduced from 2½" to 2¼" are proving difficult to seal up.

Edited July 1, 2011 by Arne

[LeonV]

Why did you reduce pipe diameter from 2.5 inch to 2.25 inch?

[Arne]

Why did you reduce pipe diameter from 2.5 inch to 2.25 inch?

The dual outlet muffler I wanted to use has a 2.25" inlet.

[LeonV]

The dual outlet muffler I wanted to use has a 2.25" inlet.

Why not go with this one?

[Arne]

Why not go with this one?

The outlets are on 4" center spacing, too far apart for this application.

***************************************************

It's done. For now, at least.

A quick note on the joint where I shortened the S-pipe - I used a stainless band clamp there. I highly recommend these for this type of joint. Seals well, seems to be quite rigid.

As for the rest - I gave up and took it to the pros, had them weld both ends of the reducer, as well as the muffler to the rear S-pipe. I might have been able to fiddle around and get the reducer joints to seal more-or-less, but there was just no way that was going to work on the Magnaflow. The inlet on the muffler was just far too sloppy a fit on the pipe. Way too much gap to clamp.

So how is it, you ask? Not bad. I still don't think I'd do it over, nor will I recommend it to others. Too much work, too expensive. I should have bought the new downpipe from MSA separately, and had a system made locally instead. Since the local exhaust shops all charge more than I hear people talk about in other parts of the country, the overall cost would probably have been about the same, but I might be even happier with the result.

The fit - now that the welding is done - is pretty good. Very solid, no rattles, leaks or interference anywhere. The tips extend about an inch farther than the previous Monza tips did. That's about as far as I'd want them to go. But on the plus side, the longer tips in combination with the welded joints seems to have eliminated the exhaust smell with the windows down.

Any concerns? Yeah. It's louder than I had hoped. No drone so far, and the note is deeper and throatier than the small-tube glasspack I had before. Sounds good when you get on it, but pretty loud then. Relatively quiet at steady cruise. If it doesn't get much louder, I think I can live with it. But if the packing in the muffler settles, I'm going to have to have another muffler added in the center, which will require a bit of rework to get away from the edge of the tunnel.

Edited July 2, 2011 by Arne