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Leland Pate 01-19-2004 08:02 PM

Custom exhaust system (A love story.
Well, I get to do this ALL OVER AGAIN... because a few minutes ago the BBS decided I put too many pictures on this thread. So, here is the abreviated story:

As some of you know, I am in the process of fabing my own dual in dual out exhaust system. Everything was going fine until I realized the Dynomax muffler I bought was built to have both inlets on one side and both outlets on the other side. As my car has SSI's I obviously need one inlet on each side and one outlet on each side.

So, since I had alreay hacked the Dynomax muffler up a bit and tack welded mandrel bends I knew I couldn't return it.
This is my story:

I decided it was worth a try to rework the interior tubing in the chamber to to make this thing work.

Here is how the muffler was set up.

This is what I wanted:

SO I put on my latex gloves, grabbed my scalpel and started tearing this thing apart.
I opened up the muffler body and removed the fiberglass packing. It looked just like the picture above. Two parallel perferated pipes (with a pied piper).
I removed the pipes by grinding off the welds at the ends. I then used card board and made a template of the chamber area.
Then I transfered the template to a piece of sheetmetal that was made out of a sectioned and flattened piece of scrap tubing. I welded this piece in the center of the muffler to create two chambers.

It looked like this:

I then cut four inches out of the center of both perferated tubes and reinstalled them... like this:

I then repacked the chambers with the fiberglass and welded it back up.

The result???

.................................................. It's.............................................. .................................................. ..................................... IT'S............................................

Leland Pate 01-19-2004 08:03 PM

FRANKENMUFFLER!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!


nostatic 01-19-2004 08:06 PM

I believe there is a law against that in California.

Then again, there is a law against *everything* in California.

Good thing my son was already asleep...I don't want him to look at such metallic audacity...too young.

Leland Pate 01-19-2004 08:10 PM

Here are a few more pics:

My hightec tube cutting system:

My welder:

My floor jack (sponsered by Pelican Parts)

My disaster area:

RSBob 01-19-2004 08:14 PM

OMG! It lives!

Scooter 01-19-2004 08:18 PM

I see you still have the John Walker's Workshop license plate frame. :)

Nice custom fabrication. Never say die, just rip it apart and make it work.

Leland Pate 01-19-2004 08:20 PM

....Never give up.... Never surender....

anh911 01-19-2004 08:28 PM

Now I'm gonna have nightmares!!
Let's hear it!! Post a sound file!!

Early_S_Man 01-19-2004 08:41 PM


You need to put a few more stitches in it ... you REALLy need to have a crossove pipe inside!!! A 2" ID one would suffice ... 3/4 of the length of the internal width ...

Otherwise, you will be giving up a bit of 'free' torque and BASS!

911pcars 01-19-2004 09:14 PM

Did I lose a post somewhere between the beginning and where we are now? You said you wanted to create a crossover flow path inside; inlet at the bottom of one side to an outlet at the top of the other side.

However, you then proceeded to install a wall inside the shell to create two essentially separate chambers; each inlet and it's outlet are now on the same side. What was the purpose of the change in strategy? Any noticeable difference besides the noise factor? No flat spots?


Moses 01-19-2004 09:20 PM

Muahahahahaha! :D :D :D :D :D

masraum 01-19-2004 09:52 PM

Couldn't you have done something like this?

Please forgive the crappy drawing, I don't have a program that's very good at this sort of thing. I need to get one.

Chuck Moreland 01-19-2004 10:04 PM

This is exactly what I suggested in the other thread, though without the beautiful CAD drawing.

Seems like this would work?

Leland Pate 01-20-2004 06:41 AM

I couldn't make it work that way, Steve. In order to get the mandrel bends to turn 90 degrees down and then another 90 degrees back. It took up too much room. Plus the inlet pipe and exit pipe would hiy each other.
It is hard to describe.

Anyway, I know I made a mess. If for nothing else, this was just good welding practice and I enjoyed every second of it.
I have looked high and low for a cross flow muffler of any brand that is 14" in length. There are none to be found. The shortest one I found was 18" long. This makes it too wide to fit between the SSI's outlets.

So, most likely the old muffler will have to go back on. But not before I try FRANKENMUFF.

Moses 01-20-2004 06:57 AM


Originally posted by Leland Pate

I have looked high and low for a cross flow muffler of any brand that is 14" in length. There are none to be found.

Leland. The Magnaflow has a 14" body. It is real. I've seen it. Sounds great. Cheap muffler. It's the same size as Frankenmuffler!

Moses 01-20-2004 07:12 AM

Leland, I think Magnaflow has changed #'s. You want the 11386 or the 14386. You can get it in stainless if you want. In this muffler, the perforated pipes form an "X" inside the muffler. Very low restriction.

Leland Pate 01-20-2004 07:14 AM

Well, I went through the catalogs for all brands at a local muffler shop and the only ones I could find were the 18" Monte Carlo crossflows.

Ok, I give. Where did you guys find the Magnaflow part numbers?

Moses 01-20-2004 07:20 AM


Originally posted by Leland Pate

Ok, I give. Where did you guys find the Magnaflow part numbers?

Bob's Flat-Six 01-20-2004 07:25 AM

Well, It does look like Frankies forehead,
I hope you put a good brain in there? AB Normal something ? :eek:

Dantilla 01-20-2004 07:31 AM

Geez- and here I just BOUGHT a muffler that was ready to bolt up. What's next? getting a big cube of aluminum and carving yourself some new wheels?


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