Muffler Replacement -- Update: got a custom cat back exhaust

[ednevell]

Did you get a good look at the stock muffler when it was cut off? A lot of people on here, myself included, want to know if the muffler is a straight through one or not.


I don't know why but my car has a louder exhaust note than any other Mirage I have seen, but it is all stock.

Now the muffler from the factory flows in all the way to the other end and the back out its a crazy design...

[ednevell]

I hope those are good pictures for you guys, watch for my post on the ebay CRAP lowering springs next weekend(weather permitting!)

http://www.ebay.com/itm/400696604568...%3AMEBIDX%3AIT

Can anybody tell me what end of the factory muffler is inlet and out let???

Little trivia for yall!

[91cavgt]

AWESOME!!! That is what is referred to as a turbo muffler. They tend to flow pretty good at low rpms but become a bit restrictive at high rpms, depending on the design of the turbo muffler. Dynomax Super Turbo mufflers have flow directors built into the muffler to help redirect exhaust gases which improve the flow of the muffler for higher RPM power. The stock muffler though, as you can see in the pictures, do not have the flow directors.

A good straight through muffler that is VERY smooth on the inside walls of the muffler should improve power but ONLY in the higher rpm areas of the power band. A typical glass pack muffler though is not smooth on the inside walls which will restrict exhaust flow, even though it is a straight through design.


Also, a way to decrease drone inside the car is to get rid of the turn down on the end of the stock exhaust. If it can be routed straight out the back of the car then the sound waves will go straight back out, instead of bouncing off of the road and reverberating back to the under side of the car, creating a drone.

[91cavgt]

I hope those are good pictures for you guys, watch for my post on the ebay CRAP lowering springs next weekend(weather permitting!)

http://www.ebay.com/itm/400696604568...%3AMEBIDX%3AIT

Can anybody tell me what end of the factory muffler is inlet and out let???

Little trivia for yall!

Turbo mufflers can be reversed so it really doesn't matter which is the inlet and which is the outlet as there is no difference in the flow. Baffled mufflers on the other hand MUST be installed in the proper direction otherwise you will have a lot of restriction to exhaust flow.

[ednevell]

AWESOME!!! That is what is referred to as a turbo muffler. They tend to flow pretty good at low rpms but become a bit restrictive at high rpms, depending on the design of the turbo muffler. Dynomax Super Turbo mufflers have flow directors built into the muffler to help redirect exhaust gases which improve the flow of the muffler for higher RPM power. The stock muffler though, as you can see in the pictures, do not have the flow directors.

A good straight through muffler that is VERY smooth on the inside walls of the muffler should improve power. A typical glass pack muffler though is not smooth on the inside walls which will restrict exhaust flow, even though it is a straight through design.


Also, a way to decrease drone inside the car is to get rid of the turn down on the end of the stock exhaust. If it can be routed straight out the back of the car then the sound waves will go straight back out, instead of bouncing off of the road and reverberating back to the under side of the car, creating a drone.

SEE why couldn't I get that answer when I was looking for it...LOL I am going back to my tube guy and getting the last resi deleted and straight out the back she goes!

Thanks 91cavgt!!!!

[silverstreak]

Hey 91cavgt, So if I'm correct the bafflepack I posted a link to in the beginning of this thread will be less, or more restrictive than the stock muffler. Also thanks ednevell for taking the time to get some internal shots of the stock muffler.

[91cavgt]

Hey 91cavgt, So if I'm correct the bafflepack I posted a link to in the beginning of this thread will be less, or more restrictive than the stock muffler. Also thanks ednevell for taking the time to get some internal shots of the stock muffler.

If the 2 internal tubes are smooth on the inside then it will flow more than the stock muffler. But if when you run your finger inside the 2 tubes, it catches on louvers that are designed to make straight through mufflers quieter(i.e. most glass pack mufflers) then it would be about the same, if not more restrictive than the stock muffler. That site does not show if the tubes are smooth inside or if the louvers stick up in the air flow.

[silverstreak]

Only pick of the inside of the bafflepack I could find, looks like this may not flow as well as I thought, or be about the same as stock.

http://www.hostthenpost.org/uploads/...88d1542b12.jpg

[91cavgt]

Only pick of the inside of the bafflepack I could find, looks like this may not flow as well as I thought, or be about the same as stock.

http://www.hostthenpost.org/uploads/...88d1542b12.jpg

Yeah, that will flow worse than stock for 2 reasons.

1. The raised louvers are there to catch the sound as it comes in to make it quieter, but in turn it also catches the exhaust and causes turbulence, which decreases flow.

2. See the flat wall right next to the small pipe in the center of the muffler? Yeah, that's bad for flow too. A good exhaust needs to be aerodynamic just like the body of a car. If things inside the exhaust are raised, just like on a car, it won't be aerodynamic. On a car, a smooth front end that directs air around the front end is more aerodynamic than a Mac truck. Exhaust is no different. If you go from a single pipe into 2, even if it is within a muffler, the exhaust needs to be gently guided in order to keep the flow up. When you put flat walls up in the flow of the exhaust, or louvers that cause turbulence, it decreases the flow rate the muffler is capable of and thus it decreases power. It might sound nice, but the power won't be the same.

[Messy Mitsu]

turbulance can be good for sound vibrations and it wouldn't hurt much if you had a lot of horsepower but with a mirage the only room for improvement is a straight smooth flow with stock or very close to stock in diameter otherwise you take a hit due to backpressure

Edit: this loss could be minimized by moving the muffler closer to the tip or would it not make much difference?