A popular question that we normally get from customers and a popular topic among car forums is “Which flows better, oval or cannon mufflers?”
A mufflers main job is designed to muffle or eliminate sound waves generated from your engine. Mufflers may look the same on the outside but not all mufflers are created equal and can use different methods or sometimes multiple combinations (Chambered, Absorption, Reverse and Twin passes) to reduce noise levels.
Chamber muffler designs can vary however the basic concept is the same. Above is an example of a factory chambered muffler design. First thing you notice is that there are 2 chambers; a main flow chamber and a resonating chamber. In the main flow chamber exhaust gasses flow through a perforated tube before exiting through to the outlet tube. While the Resonating chamber (the larger chamber) is where the sound cancellation occurs. In the resonating chamber, a specific volume of air and length is calculated to produce a wave to cancel out a certain frequency of sound. Thus reducing noise and drone level. It’s good news then for car manufactures who have strict noise levels to meet or for people who require little to low noise level.
Good for noise restriction, bad for flow since it can create unwanted back pressure in the main flow chamber.
Absorption / Straight-through Mufflers
Example of a straight through muffler. Please note this is not an Xforce muffler.
Absorption straight through mufflers consist of a single perforated tube and have virtually no restrictions and offers the most flow. A combination of stainless steel cloth/wool and fiberglass packing is used to fill in the void between the perforated tube and muffler canister, the packing helps dissipate and absorb sound waves (mainly high frequency sound). Absorption straight through type mufflers are mostly your cannon type mufflers, but can also be made in a oval type too. The easiest way to tell is to hold up the muffler in question and look through one side of it. If you can see the other side then you have a straight through muffler!
Important factors that will determine the sound characteristics:
XFORCE chooses to use the straight-through absorption design for our sports mufflers, Testing has shown that they produce maximum power gain and overall a better sounding exhaust. For our mufflers we only use the best quality material for muffler packing.First layer is a heat resistant stainless steel wool used to insulate the high temperatures generated by high flowing exhaust gases, and for best sound dampening effect we densely packed the second layer with high-grade fiber glass. XFORCE also offers many variety of muffler sizes to suit all sorts of project cars. To check them out , click here
Please note this is not an Xforce muffler.
A Reverse Flow muffler.
A reverse flow or “turbo” muffler takes the exhaust gases on an S-shaped path through the muffler. The exhaust gases travels to one end of the muffler, is turned 180 degrees and heads back to the first end. From there it is again turned 180 degrees before it passes through the outlet. Great for producing sound cancellation waves and reducing noise, but the increase in backpressure and unnatural exhaust flow ultimately means that a straight through muffler will easily out flow this design.
A combination of Chambered + reverse flow type muffler+absorption. This muffler would almost create no noise. You can see that the exhaust gases has to flow through an absorption chamber three times before exiting, and a resonating chamber is included to cancel out any remaining sound waves that are missed. By looking at the arrows, flow would be compromised in the last and middle chamber. Lots of back pressure!
Twin loop muffler
In a twin loop muffler, exhaust gases flow in a natural spiral shape path through the muffler twice before exiting the tail pipe. It has all the advantages of the absorption straight through muffler and none of the reverse. A twin loop is effectively two straight through mufflers compacted in one.
The twin loop is great for vehicles with limited space but requires maximum HP and low noise level. They are popular choices for many four cylinder naturally aspirated cars such as Honda Civic, Integra.
A VAREX muffler is a combination of a straight through and reverse type muffler. When the valve is shut closed exhaust gases are redirected away from the main flow path and through a smaller opening before exiting. Sound waves are reflected and cancel out any sound waves of the same frequency. Any escaping sound waves are dissipated and absorbed by the stainless steel wool and fiberglass packing. When the valve is opened it is essentially an absorption Straight-through Muffler providing maximum flow.
To see the full range of high performance Xforce mufflers and Adjustable Varex Mufflers visit : http://www.xforce.com.au
Please note: All pictures and images belong to their respective owners.