Muffler Maintenance

Coast Fabrication offers three levels of packing material so that racer’s can tailor the muffler to their specific needs.  The high temperature fiberglass material is most popular because of its lightweight and low cost, it works well in most normally aspirated configurations that have moderate exhaust temperatures.  The next level is stainless scrubble, which is substantially more durable, with a modest increase in weight and cost.  Scrubble packing is recommended for most engines with forced induction or other configurations where the packing sees exhaust temps exceeding 1000 degrees fahrenheit.  The third level, stainless mesh, is extremely durable but heavier and still more costly.  The mesh packing was developed to withstand extreme exhaust temperatures with sustained operation such as experienced during 24 hr. endurance races.  

 The key lesson is that muffler packing is a consumable item.  Mufflers that have been in service without inspection are likely giving away horsepower.  Please contact Coast Fabrication to purchase repack kits that will return your Coast Fab. muffler to its original performance.

 In order to supply the correct kit for your muffler Coast Fab. will need the inlet/outlet diameter, the diameter of the muffler body, and the length of the muffler body including the end caps.  In many cases records can be checked to determine the muffler size and packing configuration that you bought.  Please provide the name it was bought under and an approximate date of purchase.

Exhaust heat and high intensity acoustic pressure can cause muffler packing to disintegrate.  Independent dyno testing on exhaust systems utilizing Coast Fab. mufflers have repeatedly demonstrated that as the packing deteriorates, horsepower and throttle response deteriorate as well.  When the packing is wrapped tightly around the perforated core, exhaust gases go straight out without restriction, while at the same time the packing deadens the sound waves.  A fully packed muffler will normally make the same power as a straight pipe of the same diameter as the muffler core.  As the packing deteriorates exhaust gases migrate into the outer housing, which causes unwanted turbulence and backpressure.  In this case “louder” indicates wasted horsepower, not more horsepower.

One of the key advantages of Coast Fab. mufflers is that they can be easily disassembled for packing material inspection or replacement.  Mufflers need to be inspected regularly either by disassembly or comparative weight to determine repack intervals.  In some types of racing, teams start every race with a freshly packed muffler to insure that it will be at the absolute peak of performance.  It is unlikely that you will need to repack that often however to avoid horsepower loss regular inspection is important.  If your repack interval is more frequent than desired, more durable packing can often be substituted.  Muffler packing life is very dependant on the temperature seen by the packing.  These temperatures differ greatly due to variables in engine and exhaust configuration.  Muffler location within the exhaust system can also make a big difference.