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View Full Version : NB Muffler exploded view?



Woodk61000
09-13-2012, 09:46 PM
Thinking about picking up a spare stock muffler and modifying it to get a better sounds. Yes, I can afford to buy a good pipe from one of the suppliers but ive made it a goal to see how cheap I can build and play with this car ($1000 Garage Sale car) Anyone got a pic of the baffles inside the stock muffler?

Fastblackie
09-13-2012, 10:21 PM
I was actually thinking about getting a stock muffler off of another car the see what kind of sound I could get out of it. Just looking for quiet right now lol.

miatastuff
09-14-2012, 08:08 AM
No, but I have TONS of stock NB mufflers I would sell for $0.11/lb.

Fastblackie
09-14-2012, 08:22 AM
Well now... That should only be about $15 lol... Those suckers are heavy if they weigh anywhere near as much as an na muffler.

Woodk61000
09-14-2012, 09:09 AM
Ive got one that a guy is checking on, so I should have one next week. Probably just get out the cut off wheel and open it up it see what is inside that could be changed.

FE3tMX5
09-14-2012, 09:16 AM
NA muff cut open attached that shows all the bad (anti-performance) characteristics. Most non-performance (OE) mufflers have a section that dumps the exhaust gas into a chamber (usually full of packing) which disrupts the flow significantly, but does a great job hushing. Typically the biggest performance gain comes from a muffler that has a continuous (straight through) pipe/path for the exhaust. This pipe is perforated (no intrusion into the exhaust path) where it passes through a chamber packed with sound deadener (see magnaflow below). The exception is a non packed, chambered type muffler (flow master below) that relies on bouncing/reflecting exhaust pulses to cancel noise. My own experience shows that this type of muffler does not work well with turbochargers since the turbo significantly diminishes the exhaust pulses at the turbine wheel.

Here's a Magnaflow performance muffler cutaway:
7941

Flowmaster:
7942

Woodk61000
09-14-2012, 09:29 AM
If the NB is similar, I can already see what im going to try to do. Again, I know that the purest types are gonna give me grieft about this, but thats kind of the point. I bought the car for $1000 at a Garage Sale. My goal is to build something that I can enjoy, by using my head instead of my wallet. I know it might not flow as good as a $300 performance muffler, but I am just looking for a little more sound. Where did you get the picture of the can cut open?

MrSteel
09-14-2012, 10:47 AM
Sounds cool man, why not. If you can weld, I could see modifying the inside to
Mimic the characteristics if the higher end pipes. I'll be looking for what you
Come back with. Put my girlfriend to work with the mig welder

Woodk61000
09-14-2012, 11:54 AM
I wonder if the NB looks the same inside?

Woodk61000
09-15-2012, 07:27 PM
Picked up a stock muffler today from 4sevens. Hopefully I can get some time in the garage tomorrow to see whats inside.

Woodk61000
09-16-2012, 06:35 PM
Got it cut open today.
Starting out with my $10 muffler
7960

Cut open
7961

Check-a-fying the inside and removing the glass packing
7962

Drilled and elongated some holes in the the pipe. Just gotta weld it back up tomorrow. Hoping to get a little bit more sound, and no loss in performance.
7963

MrSteel
09-16-2012, 10:34 PM
Idk if I would take the glass out with it flowing like that, bet it ends up being loud.
will be interesting to find out.

Woodk61000
09-17-2012, 07:33 PM
Hopefully have it welded up tomorrow. Got busy at work today and couldnt get it finished.

ben91
09-17-2012, 07:55 PM
I bet that the holes you added to the center pipe section would cause a decrease in power if tested back to back vs a stock exhaust on a dyno.

Basic drawings to illustrate:

7981
7982

The arrows demonstrate exhaust flow path through the muffler.

FE3tMX5
09-17-2012, 09:24 PM
Totally agree with arrows. ;) Remove that pipe you cut up and the third wall. Cut the third pipe off at the fourth wall. Connect pipe one to pipe 3 with a perf'd pipe (like pipe 1).Drill a bunch of small holes in #3 in a effort to perforate that. Then pack all chambers with hair from two other stock mufflers.

Woodk61000
09-17-2012, 10:03 PM
I bet that the holes you added to the center pipe section would cause a decrease in power if tested back to back vs a stock exhaust on a dyno.

Basic drawings to illustrate:

7981
7982

The arrows demonstrate exhaust flow path through the muffler.

The flow is actually the other direction. Entering on the right side and flowing to the left. The gases enter at the top right and go to center section, flow down to opening at bottom and into the right chamber, then through the pipe that I drilled the hole in, and out the back. The point of the hole was to remove some of the muffling done by the counter clockwise movement of the exhaust gases. If it doesnt work, or sounds like crap, I always have my original muffler I can bolt back on and im only out $10 and about an hour of tinker time.

MrSteel
09-17-2012, 10:05 PM
Totally agree with arrows. ;) Remove that pipe you cut up and the third wall. Cut the third pipe off at the fourth wall. Connect pipe one to pipe 3 with a perf'd pipe (like pipe 1).Drill a bunch of small holes in #3 in a effort to perforate that. Then pack all chambers with hair from two other stock mufflers.

+1 to that. I still say keep the glass, but I only want a slightly louder pipe, with low tone.

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ben91
09-18-2012, 06:41 AM
It's difficult to determine orientation with the picture cropped as it is, but even if I mixed up the inlet and exit, the point is valid. You created turbulent exhaust path that will flow less well than stock. Rob's suggestion would fix that -- and will likely both flow and sound better. You also want to retain some of the fiberglass hair. The fiberglass will slow soundwaves down. I have not experimented with packing mufflers before, but if you pack a sub box, the bass sounds deeper. I think the same would hold true with the muffler.

You want to create this
http://www.mx5atlanta.com/forums/attachment.php?attachmentid=7941&d=1347628435

FE3tMX5
09-18-2012, 08:17 AM
good exhaust article here (http://www.motoiq.com/magazine_articles/id/900/how-to-make-your-own-effective-exhaust-system.aspx)

Woodk61000
09-18-2012, 08:27 AM
Thanks for all of the comments guys.

MrSteel
09-18-2012, 02:03 PM
You want to create this
http://www.mx5atlanta.com/forums/attachment.php?attachmentid=7941&d=1347628435


I bet you could cut out all the chambers of the stock pipe, and weld/clamp in a mid pipe like this one with fresh glass. I would be interested to see results from removing the one chamber and leaving the glass from stock first probably though.

Woodk61000
09-18-2012, 10:13 PM
Well, got everything welded up today and bolted back on the car. To my surprise, it is VERY close to stock sound, even with the glass packing removed and the hole cut in the pipe. Back to the drawing board I guess. 7985

FE3tMX5
09-19-2012, 09:00 AM
What?! We don't get to see what you did inside?! :ninja::lol:

Woodk61000
09-19-2012, 09:14 AM
What?! We don't get to see what you did inside?! :ninja::lol:
First page.

MrSteel
09-19-2012, 11:02 AM
First page.

If you left the chambers intact, sounds like thats the next step. I would be willing to bring my car over one afternoon if you want to start fesh.

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Woodk61000
09-19-2012, 01:39 PM
Im gonna get some patch panels and go back in and take out the perforated tube and the one I put the holes in. Just gotta have time.

Woodk61000
09-20-2012, 01:01 PM
May try an old trick I did on the Mustang I used to have. Thinking about puting a hole in the bottom of the muffler in the same chamber that the pipe I cut the elongated hole in the pipe, and weld in a short piece of pipe (2-3" long) so it is like having a turn down as well as running out the back. On a flowmaster, you would just cut a hole in the back of the muffler and weld in a turn down. I don't want to cut a big window in it again and I think this may give a decent sound, since the gases will still have to run through a couple baffles before the dump. Some flat black paint on the muffler should help hide it a bit too. I know this is Jimmy Rigged all to hell, but I still have the stocker to throw back on if this sucks completely

Fastblackie
09-20-2012, 05:20 PM
Im actually looking forward to see how this sounds. I love experiments!

MrSteel
09-20-2012, 06:05 PM
Hay man, I'm still willing to bring mine over. We can open up the middle aria. Don't have easy access to a good welder...

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Woodk61000
09-21-2012, 07:22 AM
Drilled the holes last night and must say, it sounds pretty good. Painted everything flat black so it hides my rigging pretty good. Ill get some sound clips and pictures this weekend.

Woodk61000
09-23-2012, 05:05 PM
All of the videos I tried to do with my phone just sounded windy and you couldnt really hear the sound of the muffler. I cut it back open today and im going to cut the baffles out and start from scratch. Bolted the stocker back on and enjoyed the quiet ride today, apart from the cold side intake growl.

MrSteel
09-29-2012, 10:42 AM
Did we ever get an update on this?

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Woodk61000
09-29-2012, 06:55 PM
Ended up going back stock. Sometimes this works, sometimes it doesn't. Gonna cut out the resonator and weld a straight piece in and see how it sounds then.

MrSpiker123
10-01-2012, 02:51 PM
I got a flowmeter racing muffler and it's starting to **** on me, it can hold 500hp v8's, but it can't hold a 100whp 1.6 :(

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