What Mufflers to get?

[yody]

exactly, thats what i have been saying all along...or at least trying to say!

[chicane67]

okay chicane, you just spout out a lot of techinical terms and theory stuff but none if it directly relates to mufflers/flow.

Yes it does.......

Why dont we start off with some basic exhaust theory and why gross flow isnt a factor in a properly designed, chamber type muffler, specifically the Flowmaster and what effects it.

What actually is the major characteristic of the exhaust system and what are we trying to do with "it" in the first place?

Flow means to "move or run smoothly with unbroken continuity, as in the manner characteristic of a fluid." In our case, the exhaust mixture is the fluid medium. But what isnt stated there is that the exhaust mixture is not a smooth, continuous flow. It is broken into pulses.....which means it is a component of, and has frequency.
Frequency which is a property or condition of occurring at frequent intervals, and in mathematics and physics is defined as "the number of times a specified periodic phenomenon occurs within a specified interval." There are two specific frequencies involved with this example, and they are 'audible' and 'pressure' frequencies (and/or refered to as waves). The other major factor to all of this, is the individual 'amplitudes' of these frequencies. For simplicity, we will generally refer to this as the exhaust 'signal', but will also remember that each of these 'signals' have components of frequency and amplitude.

The exhaust signal is made up of a varying pulses that change in frequency and amplitude as a function of RPM. How the wave is controlled to effectivley manipulate the pressure and velocity, via convergent and divergent vessels, is where a chambered muffler's secret lies.

Now lets get to the meat. The muffler in an exhaust system is there to control amplitude (to muffle), all the while why trying not to disrupt mass flow, in predominant theory. It also can (and does) have an effect in the modification of the signal frequency from an audible stand point. So, lets get a few things out in the open......like muffler types and how their specific designs work. There are two basic types, media filled and chambered. The media filled are pretty strait forward. They use a material packing to absorb (dampen actually) the amplitude of the pressure wave. The chambered type however, are a little more complicated. Their dampening comes from bouncing waves into each other and distrupting the pressure wave into 'phase cancellation' (very much similar to the electronic mufflers that Dennis mentioned). The chamberred type also uses volume pressure scavenging which works directly with the frequency of the exhaust signal. This effectively changes how the exhaust mixture flows thru the muffler.....and this is where gross flow measured on a flow bench, can not go. It requires the frequency components to function and accelerate the exhaust gasses thru the muffler. It is very much like a true "X" pipe exhaust system and operates just the same. 180* headers operate under the same manner.........pulse scavenging.

Flowbench numbers mean absolutly nothing in respect to the gross flow of a chambered muffler, but it does show the mean flow number......so its not really comparing apples to apples in reality.

Another factor here that has not been discussed is the temperature of the exhaust gasses and how effects flow and pressure. But that is another story and only has a limited effect in the 'big picture'....but it does have a large effect on specific exhaust components like the "X" and the internals of a chambered muffler individually.

[yody]

so how does that relate to the muffler scavenging the exhaust? time for lesson 2!

[ironroad9c1]

just buy some dang dynomax mufflers and be done..lol get the stainless steel ultraflows if you want em to last ..lol lets not make this into rocket science..lol

[yody]

i already know exactly how my exhaust systme is going to be, and yes exhaust is a science. Part of protouring isn NOT just throwing stuff on your car without doing research on it. Some of us enjoy researching and trying to understand and learn whats going on with our cars. My exhaust is;
2" primary super comp hooker headers into flowmaster 4-2-1 collector with a 3-3.5 collector with a flowmaster ball and socket adapter, into 3" exhaust going into a X pipe then into 3" ultraflo mufflers and then 3" tailpipes that dump just below the quarter panel

[chicane67]

Well, that proves the theory and tee-shirt that Virgina doesnt add too much to the gene pool..... and coming from a 5 point slow at that. Rocket science is rudementary, because of wave theory.

To answer your other question yodmiser, simply stated, in an exhaust system, any time you can create a negative pressure it helps evacuate the spent gasses and eliminates any back pressure. Kinda like a piston in a swept cylinder, heading for BDC on the intake stroke. The negative pressure pulls the mixture thru. With a muffler that operates by negative scavenging, it helps pulls the mixture from the collector and mid section.

Any time you turn a fluid medium (any fluid actually), like that of an intake or exhaust mixture more than 12*, there is a restriction in mass and mean flow. The most restrictive parts of an exhaust system are where you turn the medium in direction. The "X" helps to offset the losses from the turn at the collector down thru the transmission tunnel. A good muffler can help that as well as it draws the mixture out of the part in the system that is associated with the greatest loss.

Also, to help the exhaust system out a little, the most popular modification to help out with scavenging is to run the tail pipes one size under the rest of the system. 3.5" collector- 3.5" tubing and 3.0" tail pipes aft of the muffler. This convergent ducting increases velocity and reduces pressure....in effect, it creates a negative pressure in the muffler and helps to evacuate the exhaust system as a whole.

I did a 70.5 Camaro with a 502 that had 3.5" collectors, so I did everything in 3.5" and then 3.0" aft of the muffler because I used Dynomax 'UltraFlo's. With a Flowmaster, I would of run 3.5" aft of the muffler because of how the muffler operates. Tried both, in both of the different configurations noted above. The data showed enough to make the point worth stating.

All in all, I have done quite a few dyno sessions with different mufflers and systems designs. And ya know what? The Dynomax UltraFlo's have continuously made more power with Chevrolet engines and Flowmaster has made more power with Ford. Care to take a guess as to why??

[yody]

yeah i would like to use 3.5 into the X and out which would make everything like one big long collector but ground clearance won't allow it. The negative pressure theory makes perfect sense to me. If you do know, how do the different designs and which mufflers make a negative pressure? i take it the flowmasters do? also i guess that with the Ford firing order it creates more even exhaust pulses and the negative pressure in the flowmasters somehow help or something along the lines? i am really enjoyingg this topic! But sometimes i crave for direct examples so i can more identify with everyday use. BTW Virginia Rocks!

[ironroad9c1]

damn i try for a little humor and get kicked in the balls ,hey i'm not from here i'm just forced to stay here for the next year..lol

[chicane67]

Hey is that T-shirt thing as big of a circus act as it is being portrayed on/in the news?? Virginia isnt all that bad. I just had to get a little in.....lol

[Patrolman808]

I'm going to run the same exhaust I had on my 02 Z-28. I had true duals with 3" pipe and a Hedman X-pipe running into 1 chamber Flowmaster 3" race mufflers. It was the best sounding LS1 exhast I've ever heard. Got tons of compliments. Now that I'm adding a huge cam, mine should sound that much better. Just my opinion though..

[rumblee]

I worked on a guys 99 z28 with the most horrible sounding exhaust I had ever heard. He ran a single 3" pipe right from the y-pipe down the center of the car with 1 single chamber flowmaster clamped to it. He then mounted the muffler to the torque arm of all things with no tailpipe! It was gross..... This guy also took off some beautiful Fikse wheels and replaced them with some ugly 9 spoke chrome heavy bling bling wheels and put big stickers on the car..... oh well, its his car he can do what he wants with it.

[rumblee]

I have hooker aero chambers on my nova. I really like the way they sound and it felt like a different car when I went from dynomax super turbos to the hooker mufflers. Does anyone else use/like these mufflers or just me?

[68LSS1]

So using a smaller diameter tail pipe (muffler back) should be better with any media type muffler? And do these theories hold true to forced induction applications or just N/A. I'm assuming just N/A as with a turbo/blower you just want as little restriction as possible (looking at it from a performance stand point). Scavenging wouldn't be a issue or would it?

[1Fine69]

chicane how do you learn so much about a pipe haha. im have 2.5 inch with h pipe to 40 series flowmasters and its healthy at idle and doesnt get to much louder when throttle is applied. im chaning to 3 inch with x pipes still out the back but i dont know what mufflers to go with. the one thing i cant deal with is the raspy sound. the sound u get after u rev when it sounds like the exhaust is climbing/lingering back down to idle. i just want a rumble that gets really loud when throttle is applied but i want the muffler to flow well.....what mufler do i go with? and is the x pipe and bigger diameter a good idea?