Flowmaster Technology

Laminar Flow Technology

The Laminar Flow Technology muffler is Flowmaster’s a spin on the simple straight-through muffler. The straight-through mufflers has, as the name implies, a pipe that goes straight through the muffler. This pipe is made of perforated steel, and the sound is controlled by a hard packed acoustic material between the perforated steel pipe and the outer casing.
While this is desirable, as it does not restrict the gas flow, it also has drawbacks. Exhaust gases do not come in an even flow through the system. They are pushed out by the engine pistons, and thus come pulsing through the exhaust pipes. The muffler is there to control these pulses, and to tune the sound created by the pulsing gas. If the gases can pass through without any restriction, the only way to control the sound is to vary the amount of acoustic packing and how hard the material is packed.
The straight-through design was not good enough for the Flowmaster engineers, who wanted more control over the gas flow and the sound waves. The solution they came up with is the Flowmaster Laminar Flow Technology. The straight perforated steel pipe of the straight through muffler is replaced with two perforated cones. The cones make it possible to control the way the exhaust gases flow through the muffler. The angles of the cones and the perforation patterns can be adjusted to give the mufflers different sound and power characteristics. This way, Flowmaster can create low-pressure zones that improve exhaust gas scavenging and control the gas flow to make it more even and free from turbulence (thus “Laminar Flow Technology”). With better control of the gas flow, Flowmaster also gets more control of the sound waves. The angles of the cones are chosen to reflect the sound waves of certain wavelengths in such a way that they cancel out themselves. By combining this with carefully chosen sizing of the cones, the muffler casings and the amount of acoustic material packed into the muffler, and by varying how hard the acoustic material is packed, Flowmaster takes control over the exhaust note and tunes it to the tone desired for each and every application.
As the information recently has been de-classified, Flowmaster can now proudly make public that the company’s laminar flow technology is so effective and versatile that it has been used for many years in military stealth applications. A couple of prominent examples are the ways the US Air Force uses the laminar flow technology in the renowned Apache helicopters and in the still mysterious stealth fighter plane to control sound and heat emissions, which is key in making these airborne weapon carriers as hard to detect as possible. That the Laminar Flow Technology can be adapted both to get attention and to avoid attention shows how appropriately the Flowmaster company is named. This is a company that truly can control the flow of gases and make them behave and sound as the Flowmaster engineers desire.


By using two perforated steel cones instead of a perforated steel pipe in this variation on the straight through muffler, Flowmaster takes control over the gas flow and the sound waves. The gases come into the muffler through the Entry cone . The angle of the cone and the perforation pattern are chosen to cancel out chosen sound frequencies and to let the exhaust gases expand into the Laminar Flow Area . This controlled gas flow minimizes turbulence (and noise) inside the muffler, which improves scavenging and sound characteristics. The shaping of the Laminar Flow Area makes sound waves loose energy and directs them into the sound-absorbing Thermal Layer surrounding the gas flow chambers. The Thermal Barrier serves a dual purpose. It is important to the muffler’s sound energy absorption characteristic, and it also reduces the muffler’s exterior temperature, making it possible to place the muffler close to heat sensitive components. The gases finally flow through the Exit Cone , again an area where the angles and the perforation pattern is carefully designed to make sound waves cancel themselves out. The widening of the Exit Cone to the outlet provides an easy exit for the gases, again a feature that improves exhaust scavenging.

The Thermal Barrier