There are as many different theories and designs of mufflers as there are companies making them. The science of muffler design revolves around three major areas: 1) sound, 2) flow, 3) durability. At Billy Boat Exhaust, they have taken their 25 years of experience, their racing background, and their practical approach to design a product that has a signature tone and provides a lifetime of driving enjoyment.
There are two basic ways to muffle an internal combustion engine. First, through absorption, in which the sound waves are absorbed through a perforated core into some kind of packing material, and second, reflection, in which the sound waves are bounced off an internal baffle or back at each other in order to cancel the sound waves. At Billy Boat Exhaust, they have built thousands of exhaust systems over the years and have found that each design theory has its strengths and weaknesses. The company’s goal when they prototype a new exhaust is to create a deeper, throatier tone for the exhaust, increase the volume at idle and while under acceleration, but keep the interior volume quiet while at cruise and free of any “drone”.
In order to meet these criteria, they use a combination of each design style in their exhaust systems. The company’s engineers do not use “off the shelf” mufflers in their exhaust systems - each application is evaluated, and they build what is the optimal solution for each vehicle. This provides Billy Boat Exhaust with the opportunity to achieve the ultimate sound and performance.
While most muffler companies use a standard round tube design, Billy Boat Exhaust uses a square tube design. This tube design allows for more volume in the muffler tube and also for more perforated surface area inside the tube. More volume means better flow and less restriction, while the increased surface area means more perforated material to absorb sound waves. The company also uses perforated arrows inside the tubes to direct the exhaust flow in a lazy S pattern, helping increase the efficiency of the absorption side of the muffler.
The packing material around these perforated square tubes is equally as important as the design, because different materials have different acoustic properties. These materials must be durable and provide a lifetime of enjoyment, yet also emit the deep tones which create Billy Boat Exhaust’s signature tone. The company uses two different types of packing materials in their mufflers, a stainless steel mesh material and an extremely high-temperature ceramic material. The stainless steel mesh is wrapped around all muffler cores to add a layer of durability to each muffler, while the ceramic material is used as a blanket around the core or as a void fill inside the muffler chamber. The combination of these two materials is unique in the exhaust industry and creates the foundation for Billy Boat Exhaust’s deep, throaty muscle car tone.
Each of the mufflers in a Billy Boat Exhaust system also has a reflection component to it. The company uses internal Helmholtz chambers in each muffler, which are dead-end tubes branched off of the main muffler core. The name comes from a device created in the 1850s by Hermann von Helmholtz, which he used to identify various frequencies and sound waves. As the exhaust flows by these tubes, pressure is reduced and the sound waves reflect back in the opposite direction. At Billy Boat Exhaust, they use these internal tubes to reflect and cancel the high-pitched sound waves which cause “drone” in the exhaust.
Durability is also an important component of each muffler. Billy Boat Exhaust uses only 18 or 20 gauge 304 stainless steel for their muffler cases, and the muffler end plates are all 14 gauge 304 stainless steel. Each muffler is hand built according to exact design specifications for each application, and then either hand TIG-welded or welded in the company’s robotic welding cell. At Billy Boat Exhaust, they have a goal to build the best performing, best sounding and highest-quality exhaust systems on the market. Their manufacturing techniques and signature tone are unique in the industry in order to provide their customers with a “moment of adrenaline and a lifetime of performance.”
Each Billy Boat Performance Exhaust system incorporates 3-generations of fabrication skill and racing talent. Every system starts with T-304 stainless steel, known throughout the industry as the highest-quality material, practical for after-cat exhaust applications. All exhaust tubing is mandrel bent on sophisticated CNC machinery for a precise fit and uninterrupted exhaust flow. What’s more, the use of T-304 stainless steel flanges offers high strength and complete resistance to harsh elements. All hangers, resonators, and tips are T-304 stainless steel as well.
The Billy Boat Performance Exhaust PRT after-cat system employs exhaust technology unique to the aftermarket. So unique, in fact, it doesn’t use a muffler at all. The Billy Boat Performance Exhaust PRT system is simple in design, though more complex in theory, which suggests that you can have a mellow sound at cruising speeds and a sport note when you’re tearing up the streets. It allows true straight through exhaust passage under aggressive driving conditions.