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3" Exhaust... for NA modified engine. Muffler options?


inline6

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If you want something really nice and can spend some money, there's always the Coast Fab muffler:

 

http://www.coastfab.com/mufflers.html

 

The can be disassembled and the packing material replaced. They offer fiberglass or stainless packing and it looks like they ahve them on sale. These are by far the best mufflers you can buy.

 

I did some exhaust for some SCCA guy once, he had a Burn's muffler. He told me to just weld it on instead of taking a break and going to get some slip-on stuff. I feel so bad for ruining it...

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Also, be careful about adding glass packs, etc. You need to purchase a high quality, all stainless unit. Here's a pic of one I took off a customer car after he built his own exhaust and ran it for 6 months behind a 225 HP L6:

 

The same goes for turbo / chambered mufflers (you get what you pay for, and look inside your pipes before installing it, you may see things you don't like. )

 

I was trying to decide between a Cherry Bomb or Thrush 3" muffler, and ended up with the latter after seeing a 'open box' Cherry Bomb on Ebay. Cherry Bomb's advertising doesn't show a picture of the 3" , probably because as the IN pipe goes into the muffler, it necks down to 2.5" !! So internet/ magazine buyer beware, make sure you know what EXACTLY your model looks like before you buy it!

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Many of the rotary guys use a "power pulse presilencer" which is a stainless steel packed muffler.

 

Rotaries have such a huge overlap that they can't tolerate any backpressure, make big heat, and are super loud.

 

I'm not sure how much it will attenuate sound but I used to use one on each primary pipe and then a huge single chamber muffler after it was collected near the rear of the car.

 

cf96f5de-faaf-4540-8bb6-081da258dcbd-800.jpg

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I think all the parts are here. Wondering if this will be enough "muffling"... ;) --- I kinda doubt it.

 

3" mandrel bends and straight pipe:

post-4218-092104700 1349143151_thumb.jpg

 

Mufflers, exhaust tip, band clamps, 3/8" rod (to make hangers), and rubber strap hangers:

post-4218-067941700 1349143166_thumb.jpg

 

The Nismo header (1.75" primaries) that needs to be "modified":

post-4218-018357300 1349143285_thumb.jpg

 

The "Merge Collector":

post-4218-094758000 1349143915_thumb.jpg

 

Once the header has been modified to clear the existing floor, I'll be making some connectors to the dual inlets on the merge collector. The header, fabbed connectors, and merge collector are all made out of mild steel. They will be sent off to be ceramic coated. The rest of the system is stainless.

Edited by inline6
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What I would like to know is... will more mufflers muffle more, or is there a diminishing returns type deal going on?

 

What I'd like to do is stick as many glasspacks as I can anywhere they will fit--but only if it would actually make things quieter. Or, what's a good chambered design that muffles well... while not restricting flow?

Edited by BLOZ UP
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Nice Power Point that helps people understand exhaust system noise.

 

http://www.enoisecon...arrier_wall.pdf

 

 

Hmmm. Even without the three beers, I don't think I'd follow this without spending a whole lot of time with it. I will say, that my Honda S2000 clearly has a side branch resonator in the factory exhaust. Always wondered why that dead end pipe was there. My theory was it was there to make the two lengths of pipe after the Y the same length... making the tonal quality or pitch of the sound the same for both.

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What I gathered was chambered muffler then a packed muffler, as long as you can fit, and a small non-resonating tip.

 

Which is what I had on my older Z, but the other way around. One resonator in the cat's place, and then a Y right before two dynomax chambered mufflers. Sounded good--and more importantly, it was quiet.

 

On my current one, I've got 3 packed mufflers at the moment, 2 Vibrant 12" and one Magnaflow 12". The magnaflow's kind of crappy. It's a bit too loud for me. I added a tip and it made quiet a difference to bring the end of the exhaust out from under the rear bumper to beyond it. Still a little on the loud side.

Edited by BLOZ UP
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Nice Power Point that helps people understand exhaust system noise.

 

http://www.enoisecon...arrier_wall.pdf

 

John, that is a GREAT find, thanks for posting that up here! A few years back I was doing research for school on exhaust systems and was surprised how hard it was to find even mildly technical information; or finding only NASA level stuff! (Yes, I actually found old NACA 50's files on Jet exhausts. Not what I was looking for, but good reading nonetheless.)

 

I wonder if there's some place within this forum that we can put files like this (or links) as a technical library. I used to have a Ford Ranger, and The Ranger Station has a GREAT technical library I wish we had here on hybridz. The Ranger Station Stickies are great in their own way, but the forum format isn't the greatest for a lot of our 'how to guides' and information like this.

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  • 1 month later...

What I would like to know is... will more mufflers muffle more, or is there a diminishing returns type deal going on?

 

What I'd like to do is stick as many glasspacks as I can anywhere they will fit--but only if it would actually make things quieter. Or, what's a good chambered design that muffles well... while not restricting flow?

 

I worked on a Rolls that had either six or eight mufflers and a pretty big V8. It was quiet as a mouse while driving, not sure if it was the mufflers or the dense deep carpet on the floor. The best way to muffle I have found is to put a hair dryer on the manifold, but that is off topic.

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  • 4 weeks later...

Time for an update on the 3" exhaust.  I have been working on it when I have time, fitting it all together.  This past weekend I finally got to start welding the stainless stuff together with my little MIG welder.  It is difficult to make the welds anything but fugly.   <_<

 

The tip isn't welded on yet... I think I like it the way it is (length of it that is), but I'm going to look at it each time I walk by for a few days before I make up my mind.  

post-4218-0-92296200-1354579905_thumb.jpg

 

This 6" round Magnaflow fits nicely:

post-4218-0-10910900-1354579905_thumb.jpg

 

Rear hanger isn't supporting the weight of the exhaust at the moment.  I purposely located the stainless wire here at the bottom of the pipe going under the diff... in the case the pipe drags on the road at any time, this will act as a "pad" to keep the pipe from getting scraped up.  I'm thinking the exhaust will drop about an 1/8th once all the joints are tightened up and I remove the jack stands:

post-4218-0-01904000-1354579904_thumb.jpg

 

Trying to keep the pipe as close to the car as possible...

post-4218-0-42287500-1354579902_thumb.jpg

 

My ugly welds...  I tried practicing on some more scrap tonight.

post-4218-0-52723900-1354579901_thumb.jpg

 

5" muffler located in the driveshaft tunnel:

post-4218-0-34173000-1354579900_thumb.jpg

 

Merge collector fitted as close to the header as I could get it:

post-4218-0-52565800-1354579899_thumb.jpg

 

Lots of pieces necessary here to fit the header to the merge collector:

post-4218-0-36504500-1354579898_thumb.jpg

 

 

I hope to finish all the welding this week/week end.  Now if I could just locate an LD28 water pump, I could get this thing started.   :-P

Edited by inline6
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