22 dollar muffler
#31
12-10-2008, 07:22 PM
Veteran
the stock muffler is 38 inches including the in and out "nipples."
A chambered muffler flows just as well as a "see thru" design.
Back pressure is not a desireable trait, but exhaust velocity is. Folks commonly believe that too big an exhaust reduces back pressure and this is what reduces a vehicle's bottom end torque. What really happens is the exhaust gases slow down and cool in the large pipe and a bottleneck occurs in the system before the exhaust clears the tail pipe. The "scavenging" effect is lost. This is why racers sometimes elect to jet hot coat the entire exhaust system to keep the exhaust gases as hot as they can before it clears the tail pipe.
A chambered muffler flows just as well as a "see thru" design.
Back pressure is not a desireable trait, but exhaust velocity is. Folks commonly believe that too big an exhaust reduces back pressure and this is what reduces a vehicle's bottom end torque. What really happens is the exhaust gases slow down and cool in the large pipe and a bottleneck occurs in the system before the exhaust clears the tail pipe. The "scavenging" effect is lost. This is why racers sometimes elect to jet hot coat the entire exhaust system to keep the exhaust gases as hot as they can before it clears the tail pipe.
haha apparently haha but yes your fault haha
Last edited by dodgeman22; 12-10-2008 at 07:22 PM. Reason: spelling
#32
12-10-2008, 08:21 PM
Grand Champion
Back pressure.
On a chopped exhaust back pressure is not that important since the piping is so short between the end of the pipe and the motor.
My point is, on systems like a cat back exhaust from Magnaflow, you can see through the muffler. That leaves very little pent up pressure to accelerate the exhaust gas.
If there is no pressure, on that system, you are relying on the velocity from the motor to push the gas out.
Last edited by Laramie1997; 12-11-2008 at 02:33 AM.
#33
12-10-2008, 08:36 PM
Legend
the stock muffler is 38 inches including the in and out "nipples."
A chambered muffler flows just as well as a "see thru" design.
Back pressure is not a desireable trait, but exhaust velocity is. Folks commonly believe that too big an exhaust reduces back pressure and this is what reduces a vehicle's bottom end torque. What really happens is the exhaust gases slow down and cool in the large pipe and a bottleneck occurs in the system before the exhaust clears the tail pipe. The "scavenging" effect is lost. This is why racers sometimes elect to jet hot coat the entire exhaust system to keep the exhaust gases as hot as they can before it clears the tail pipe.
A chambered muffler flows just as well as a "see thru" design.
Back pressure is not a desireable trait, but exhaust velocity is. Folks commonly believe that too big an exhaust reduces back pressure and this is what reduces a vehicle's bottom end torque. What really happens is the exhaust gases slow down and cool in the large pipe and a bottleneck occurs in the system before the exhaust clears the tail pipe. The "scavenging" effect is lost. This is why racers sometimes elect to jet hot coat the entire exhaust system to keep the exhaust gases as hot as they can before it clears the tail pipe.
#35
12-11-2008, 08:24 AM
Legend
Back pressure does not cause velocity, it inhibits it. Gases from combustion don't travel in a constant flow, they are pulses caused by the opening and closing of exhaust valves in the combustion chambers. Each pulse travels down the exhaust and out the back in a compression wave (the same type of wave that transmits sound to your ears). Due the nature of the pulsed emissions there is an area of high pressure at the front of the pulse and a vacuum at the back of it. Tuning an exhaust to the correct size uses this vacuum to draw the next burnt charge out of the cylinder. Reducing the pipe size restricts the pulse so much the wave won't travel fast enough or in a pulse like pattern to create the vacuum, too big and the pulse spreads out and slows so that the next pulse hits it and pushes against it. Back pressure is a reverse pressure working against the system, Usually by choking the pulses off with too small tubing or a restrictive cat or muffler. The only other way to create back pressure would be to try to run air or exhaust contrary to the flow, but I see no benefit to ever doing that.
The shortest exhaust that can maximize scavenging and keep the driver safe from breathing fumes would probably be the best, yes. Tubing size needs to be matched to the power your making.
The shortest exhaust that can maximize scavenging and keep the driver safe from breathing fumes would probably be the best, yes. Tubing size needs to be matched to the power your making.
