Author Topic: Anyone try to make MAC 4-1 quieter?  (Read 2251 times)

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Offline ralt12

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Anyone try to make MAC 4-1 quieter?
« on: March 18, 2008, 01:10:11 PM »
or, at least a more mellow tone? The neighbors are not loving this new exhaust...

Offline hapsh

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Re: Anyone try to make MAC 4-1 quieter?
« Reply #1 on: March 18, 2008, 01:45:19 PM »
Check out the plumbing section at Home Depot and look for some Copper reducers and elbows.   I am not sure of the diameter of the output on the Mac, but in the past I quieted my Thunderbird exhaust by putting a 2" to 1" reducer on the tip.  The extra back pressure really helps.  If that is not enough put an elbow pointing the exhaust to the road.  Yeah it possibly drops a few horses, but it also seems to help any midrange flatspot you may have.  To install just notch the big end and attach with a hose clamp.  If you want to do a quick test just use a piece of beercan bent over the tip attached with a hose clamp.  Poke a few holes in it and check out the difference.
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Offline Dunstall_74

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Re: Anyone try to make MAC 4-1 quieter?
« Reply #2 on: March 18, 2008, 01:46:40 PM »
My neighbors weren't too fond of me either after I bolted on my 4-1 header w/straight pipe.  I searched all over the place for a replacement baffle and end cap to no avail.  I ended up having to have my brother fabricate an end piece out of stainless sheet metal, and a 10"stainless pipe w/holes drilled.  It turned out really nice and quieted it down quite a bit.  As far as a simple fix that you can just buy from the store , Not really sure.   
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Offline shoemanII

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Re: Anyone try to make MAC 4-1 quieter?
« Reply #3 on: March 18, 2008, 02:24:46 PM »
can the removable baffle be, ah, baffled?  some screens tacked over the interior piping end(s) may help.  thinking of plates w/1/8inch drilled holes to bust up air flow.  good luck on this.
bobp 

maybe add some some packing inside?  most aftermarket mufflers need repacking at some point, they sound kinda raspy when it's needed.  two brothers, yosh, etc     
« Last Edit: March 18, 2008, 05:03:15 PM by shoemanII »
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okie

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Re: Anyone try to make MAC 4-1 quieter?
« Reply #4 on: March 19, 2008, 05:13:14 AM »
Take the baffle out.  Wrap it with Muffler packing.  Wrap the packing with mechanic's wire.  Reinstall the baffle.  Much quieter.  More mellow sound.

Offline KB02

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Re: Anyone try to make MAC 4-1 quieter?
« Reply #5 on: March 19, 2008, 09:04:57 AM »
Take the baffle out.  Wrap it with Muffler packing.  Wrap the packing with mechanic's wire.  Reinstall the baffle.  Much quieter.  More mellow sound.

Unless their baffles have changed since I owned one, I doubt that will work. Forgive the crudity of my drawing, but below is a basic picture of the "baffle" inside a MAC can.

The "Baffle" is essentially just to pipes that open at different end of the exhaust. The exhaust gases flow in from the header up to the inner plate which has one whole in it. This hole is connected to a pipe that goes into, and empties out on the far side of the can area.. The gases then have to travel back to the front of the can to enter the exit pipe, and then out of the can.

To wrap this in exhaust packing will, essentially, render the exhaust unusable because the gases will have no way to get from one pipe to the other.

WITH THAT SAID: You don't have too bad an idea there, it would just take a little bit of work to implement. basically, you would need to replace the two pipe system with one straight-through, perforated pipe, similar to what other exhaust manufacturers use in their baffles. You know, something that will actually "Baffle" the sound.

I put a lot of thought into this when I had my old Nighthawk 750 ('83). It had a MAC can that I couldn't stand. I never got the chance to try any of this as, at the time, I was a staving college student without the time, money or training to try any of this stuff. I still don't know if this would work or not, but the "Racing pipes" on my Ducati are basically just straight, perforated pipes with packing all around them. I started it up once without the slip ons on. Never again...   ;D
« Last Edit: March 19, 2008, 09:10:35 AM by KB02 »
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Offline merc2dogs

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Re: Anyone try to make MAC 4-1 quieter?
« Reply #6 on: March 19, 2008, 10:55:39 AM »
nice diagram there.
 
 fiberglass wrapping would end up blowing out after a surprisingly short time with that tube assembly.
 
 Alternative is to loosly wrap a few turns of metal window screen over it secure it at the center of the tubes with a couple wraps of wire to leave the ends loose. packed correctly it will be almost transparent to the exhaust, but serve to lower the sound levels. amount of screen to use depends on sound levels you're trying for.
 It works best to knock of the sharper tones without eliminating the deeper tones so you have a low rumble

 It take surprisingly little material to quiet an exhaust.

ken.