Talk:Muffler

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Contents 1 History of Mufflers 2 Cleanup 3 Muffler Description 4 Anti muffler 5 Muffler Advantages

[edit] History of Mufflers

Please excuse me if I'm wrong, but didn't mufflers exist before the late 20th century? I read the article about Hiram Percy Maxim, but he died in 1936. There is very little about the history of the muffler (or silencer) to be found on Wikipedia. Shanoman 20:27, 20 April 2007 (UTC)

[edit] Cleanup

This article is a mess. It makes (or rather, made) claims on performance impact of various mufflers without any sources whatsoever, has comments strewn into the article at various places, and seems riddled with opinion.--Oni Ookami Alfador^Talk|@ 14:08, 26 July 2007 (UTC)

[edit] Muffler Description

Mufflers also decrease sound by absorbing pressure pulses. Modern muffler walls are built in layers, with a thicker core material, to help absorb sound. Glasspacks use thicker glass insulation in place of a resonator chamber to decrease sound while also decreasing backpressure. LostCause 17:17, 3 August 2007 (UTC)

[edit] Anti muffler

Are there devices that allow for an INCREASE of sound from the exhaust? Something for "show". If so, what are they called. And are they legal, etc.

Answer: In the car exhaust industry we spend a great amount of time optimising the sound and minimising the backpressure of the system, so any changes you make to the mufflers will most likely worsen the overal performance of the muffler. By, for example, increasing the tailpipe diameter you will certainly increase the order noise coming from the engine and decrease the flow noise (and quite likely you will only get a small decrease in backpressure). Take into account that the engine order acoustics and the backpressure of the muffler work against each other (improve one and you will most likely get a negative impact on the other). So these mufflers (original equipment) are finetuned to get an overal performance which is satisfactory for both acoustics and backpressure. Some young boy racers, however, like to put large diameter tailpipes in their exhaust systems thinking they get loads of extra horse power (wrong) and thinking that their loud cars sound great (wrong again). Just imagine travelling in one of these cars for 400 km non-stop and if you still like the sound then I would be very surprised. By the way, you could be braking the law depending on the country you are driving in. —Preceding unsigned comment added by Herranzd (talk • contribs) 22:15, 19 September 2007 (UTC)

[edit] Muffler Advantages

I am afraid the statement "Mufflers that reduce backpressure" is misleading. Any muffler that is introduced in the flow path will be seen as a restriction by the gas and will generate a certain amount of Total Pressure loss. The term "backpressure" is used in the industry to designate the difference in Static Pressure between two different locations (lets say just upstream and just downstream of the muffler- positions 1 and 2 respectively).

Backpressure= P_static1 - P_static2

Lets assume the following case:

If the diameter of the pipe just upstream is the same as that of the pipe just downstream and the gas density doesn't change much, then the backpressure will be equal to the Total Pressure loss:

Total Pressure loss = P_Total1-P_total2 = (P_static1 + P_dynamic1) - (P_static2 + P_dynamic2) = P_static1 - P_static2

This is true since, for this particular condition, P_dynamic1 = P_dynamic2 = ½ρV² , cancelling out in the equation. Where ρ is the gas density and V the gas speed.

The dynamic Pressure at both locations is the same since we know that the mass flow rate is constant (the same at both locations 1 and 2):

Mass FLow Rate = ρAV = constant, where A is the cross sectional area of the pipe and V is the gas speed.

Now, since we know that the density (ρ) is roughly the same and the diameter of the pipes is the same, then V₁ must be equal to V₂. Hence the dynamic pressure is the same at both locations 1 and 2. Therefore the backpressure will be positive and equal to the Total Pressure loss so we cannot say that a muffler reduces the backpressure in an exhaust system. This would only be possible if the muffler introduces energy to the gas rather than extracting it. This is yet to be invented. I suggest that the statement could say something such as "Mufflers with low backpressure where invented ...." or similar. —Preceding unsigned comment added by 85.54.141.137 (talk) 21:47, 19 September 2007 (UTC)

-G —Preceding unsigned comment added by 67.68.62.68 (talk) 20:16, August 25, 2007 (UTC)