A Look inside the Stock Muffler

[Piratetip]

This is more of just an informative post than anything.

I had originally planned to enlarge both the inlet and 2 outlets of the stock muffler to accommodate a 3" exhaust.
Mainly to keep the stock look but be able to flow much more.
But after closer inspection the stock muffler is much more complex than I initially thought.
Also it is not worth modifying at all, which is unfortunate because it is actually very well made.
It has a double wall construction and is a decent grade of stainless.
My stock muffler is dirty but it is not rusting.

So to have a look inside I took my cutoff wheel and made a large opening, had to cut around a 4 spot welds as well.






The muffler has 3 baffle sections.
There are multiple paths for the exhaust flow to go depending on flow rates / rpm ect..
From what I am seeing a low volume of gas is able to travel through the small holes on the outside of the pipes and go straight through to the 2 outlets.
These small holes are in baffle sections 1 and 2.

At higher flow rates the exhaust gasses likely take the path I have drawn on the photo.
Skip baffle 1, travel through baffle 2, make a u turn in baffle 3, back through baffle 2, make another u turn in baffle 1 and travel out the 2 outlets.
Since none of the pipes are connected, the gasses are likely redirected in multiple different directions and take the path of least resistance.



Anyway I thought it was interesting.
Probably not too many people still using the stock muffler anyway.

I haven't seen anyone open one of these up before, so I thought I would post up my findings.

 

[suprarx7nut]

Neato!

 

[plaaya69]

Nice. I almost forgot how quiet the OEM muffler even on the turbo's.

 

[Silver MK3]

Very interesting. I should have cut mine open when I replaced it just to see how much rust was inside. I'm impressed yours is in such good shape. Mine was pretty well rusted, even being a southern car.

 

[GC89]

Great post, way more complex than I would have expected.

 

[Piratetip]

Very interesting. I should have cut mine open when I replaced it just to see how much rust was inside. I'm impressed yours is in such good shape. Mine was pretty well rusted, even being a southern car.

Yeah being always a northern car with 160,000+ miles the exhaust was in dang good shape, even most of the piping was clean as well.
I guess its possible it was replaced at some point by a previous owner, but not sure on that.

 

[te72]

Thanks for sharing your findings Pirate. Mine fell off my 88 NA back in the day, the weld failed right at the inlet / pipe joint. That was an embarrassing day or two... everybody trying to race me from the stop lights, that car was so slow until you got the weight out of its own way haha.

Very quiet though, I do remember that.

Also, are you wearing Ariat boots? They look like mine...

 

[Piratetip]

No. Just wolverine i believe.

 

[Koenigturbo]

Damm Piratetip you get up early.

 

[3p141592654]

Nice post. I still have mine in the garage. Replacing it with my HKS I was surprised how much the low end torque improved. There is a price to pay for that quietness.

 

[Koenigturbo]

Either the muffler is really huge and the muffler fell on you or your a tiny dude with regular size feet,...

 

[Piratetip]

Damm Piratetip you get up early.

Haha. Yeah my day usually begins when my kids get me up at 5:30AM.

 

[Piratetip]

Either the muffler is really huge and the muffler fell on you or your a tiny dude with regular size feet,...

The stock muffler is very big.
Though the replacement one I have now is about as big. But with far different construction inside.

 

[te72]

Heh, my HKS Silent Hipower is more of a suggestion than a muffler, by comparison.

 

[Piratetip]

Heh, my HKS Silent Hipower is more of a suggestion than a muffler, by comparison.

Same.
My replacement muffler is essentially straight through pipe perforated with some packing material inside.

 

[te72]

The Silent Hipower has an interesting method of sound attenuation, before the tip, it allows some of the air to get cycled into where the packing material is. It's tolerable at speed, and I don't think my specific case is a fair review of it, because my rear floor pan is a fairly thin sheet of aluminum... I'm sure my car is louder than most, apples to apples on the exhaust.

 

[Chambers]

This is cool! I just put a factory exhaust on my Rat Soup to get it through inspection... sooooo quiet, I can even hear my self think haha

 

[Old Radar]

Anyway I thought it was interesting.
Probably not too many people still using the stock muffler anyway.

I haven't seen anyone open one of these up before, so I thought I would post up my findings.

It was very interesting! I don't know what the dwindling number of stock muffler users is, but you can scratch one more--I just installed a Tanabe Medallion Touring catback--but I'm keeping my OEM exhaust in case I want to go back. As you can see, it's in excellent shape for being 29 years old and pushing 150,000 miles. The only issue is there is something heavy clunking around inside the resonator. I thought the resonator was just an empty expansion chamber.

Did you by any chance open yours up to see what is actually inside?

 

[Piratetip]

The resonator got thrown in the trash probably 10 years ago.

 

[Old Radar]

Has anyone else ever cut open their resonator or can anyone say with reasonable certainty what would be clunking around inside it? I have difficulty believing it would be some rusted off internal part, given the overall condition of the components.