Flowmater Fabrication

[echrisconnor]

I've been wanting to build up a Flowmaster dual in-dual out muffler for a while now. I've looked at a bunch of the threads and have a few questions for those who have built their own.

Question 1: Which are the best mufflers to use for this application. I've found the Flowmaster 42582 and the Dynomax 17725. Any preferences? Any others? Sources?

Question 2: What is the best design? I've seen two different layouts, one with the input from the headers on the top, the other with it on the bottom. The in on the bottom (as in the diagram) looks easiest to fabricate.


easier?

harder?

Question 3. What parts do I need and where to get them? I assume that a couple 90' bends, depending on the approach, and a few straight sections of 2 1/2" (or whatever diameter comes from the muffler) sections of pipe. Plus 2", 2 bolt flanges to meet with HEs.

Question 4. Where to get good straps to replace the exisiting muffler straps?

[Leland Pate]

As soon as you find a source for straps, let me know... I'm still looking.

As for layout... I drew the one on the top. It was a basic rough idea of what I was going for.
The two 90 degree turns for the tips did not happen as I had originally planned. It ended up being a lot easier than pictured above. Fist, there isn't room for two 90 degree bends, and second, it was a hell of a lot easier to make the pipes slope at an angle from the muffler.
I'll dig up a picture of my finished product.
Hopefully that'll help.

[Leland Pate]

Here are a few shots of how it turned out on my workbench.

[Jack Olsen]

From a 'looks' perspective, definitely put your outlets up top. Otherwise, you get that weird look of the outlets basically coming straight out like handlebars or something.

I wasn't able to do my B&B muffler this way, because the inlet end had been 'modified' with a hammer. So we had to bring the outlets up as much as possible:



Without a mod like that, it looked, well, really bad:

[echrisconnor]

Leland-- thanks. Apologies for pirating your picture, but your setup looks good. I see you went with the Magnaflow. Any results? Where'd you get your bends and flanges?

Jack-- I've seen your setup. One of the shots in the Excellence article shows it pretty well. I agree that from a looks perspective it might be better, however on later cars with the rear valence, most of that will be obscured. Leland's setup looks easier for the novice welder and home-fabricator.

[Jack Olsen]

Leland's is better. Mine has the outlets down below only because I didn't have a choice. When I replace the B&B, I'm going to set mine up like Leland's.

[Bill Verburg]

I like mine


Installed

[echrisconnor]

Nice setups. Looks like the in on the bottom will be the way I go.

Where'd folks get their tips?

Sources for mandrel bent tubing

Output from SSI's and most other headers are 2" right (for sub-3.6 engines) ? Is there a 2 1/2 - 2" adapter, or do you get 2 1/2" pipe and weld that up straight to your flange?

[rick conrath]

Check out Burns Stainless. Amazing stuff.
Rick
'78 930

[bigrubberjeep]

Oooohhhh I cant wait till I get some rumble under my ass!

[echrisconnor]

Rick, is Burns stainless just a source for tubing -- or is this a source for straps? I'll probably build mine out of mild steel, since I don't have a setup for welding stainless.

Leland. To get that angle on the top did you just bend the tube down and weld it in place?

[Moses]

Let me cast a vote for the "handlebar" exhaust. I like the parallel, straight back pipes. As for mufflers, I'm completely thrilled with the Dynomax Super Turbo 17725. It has a low rumble at idle, but not as loud and raw as a flowmaster. At high RPM's it howls and turns heads. Sounds like an F1. I have no muffler straps, a welded "L" bracket bolts onto the bottom of the motor. Solid support. Easy access if you need to pull the muffler.

[Bill Verburg]

SSI collectors are 2" OD(1 7/8" ID) Here is a pic of the flanges that you need

Look at the one on the right it is occluded by the stock gasket, be sure to clean that sort of thng up.


You just need 2 ss U bends to cut and weld to suit


The pieces are commonly available at hot rod sites, Burns has a great selection.

Fabiani tips are great but pricey.

[echrisconnor]

Bill. So you used a 2" flange, and I assume 2 1/4" OD tubing? Did you just butt the tubing up to the flange and weld? Also with the two U bends, did you just cut them in half to get four J bends, rather than buying discreet J's?

Finally, I've looked all over and can't find those straps. I've looked in Summit Racing, and zipped around the Burns Stainless site & couldn't find any. Any suggestions?

[rennch]

Chris,

Did you get your new setup installed? I'd love to check it out...I'm in the market as well.

mike

Oh..and if you need any fabrication work, Ken's Muffler (Now called Classic Muffler) in longmont is where all of us racer types go.

[jmz]

anybody have an idea where someone who is time deprived could purchase a set-up like this?

[ubiquity0]

Find someone who is selling theirs. Or just ask a good knowledgeable shop to fabricate one for you.

[dean]

If you can weld you can make your own muffler straps. I personally like welding a tab on the muffler then bolting that to a bracket that I make also. Straps are for bras and thongs. just kidding

[iamchappy]

If the stock straps dont work for you try these guys they have everything.
http://www.vossind.com/index.html