|WikiProject Automobiles||(Rated C-class, Mid-importance)|
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)
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 AlfadorTalk|@ 14:08, 26 July 2007 (UTC)
"Motorcycle enthusiasts sometimes use the term "raygun," or "pea-shooter" for the old shape of motorcycle exhaust silencer/muffler with a long straight cylindrical barrel that merged roundedly at each end into the pipe, as in this image and this image." Why don't we include the images in the page instead of linking to them? —Preceding unsigned comment added by Dannysjgdf (talk • contribs) 16:10, 29 April 2009 (UTC)
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)
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)
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= Pstatic1 - Pstatic2
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 = PTotal1-Ptotal2 = (Pstatic1 + Pdynamic1) - (Pstatic2 + Pdynamic2) = Pstatic1 - Pstatic2
This is true since, for this particular condition, Pdynamic1 = Pdynamic2 = 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 18.104.22.168 (talk) 21:47, 19 September 2007 (UTC)
- The analysis of backpressure above is over-simplistic because it treats the muffler as only a restriction. The Howstuffworks: "How Mufflers Work" reference explains how resonance is part of the muffler function. With resonance the mass flow rates V1 and V2 are not equal. At resonant frequency, V1 is pulsating and V2 is steady (this cancellation cannot occur at all the frequencies the engine emits). Energy is stored in the resonance. The average backpressure must be positive but it is not constant and during part of an exhaust cycle its instantaneous value reduces and may go negative. Good 4-stroke engine performance depends on efficient extraction of exhaust gas during the part of the engine cycle when the exhaust valve opens and relatively high backpressure on other parts of the cycle is tolerable.Cuddlyable3 (talk) 07:22, 14 October 2009 (UTC)
Types and positions of mufflers
- With cars, lengthwise underneath, blowing backwards at the rear
- To the sides before the rear wheels.
- With large diesel-powered trucks:-
- Mounted vertically behind the cab
- Crosswise under the front of the cab, blowing sideways.
- With motorcycles:
- Usually, beside the engine and rear wheel blowing backwards.
- In more modern motorcycles, under the seat blowing backwards from under the back of the seat. (Under-slung)
- Under-engine exhausts first reached popularity with Buell motorcycles, though by 2008 most manufacturers began using the under-engine design as well.
Motorcycle enthusiasts sometimes use the term "raygun," "drag pipes", "pea-shooter" or "hotdog-style" for the old shape of motorcycle exhaust silencer/muffler with a long straight cylindrical barrel that merged roundedly at each end into the pipe.