by P Sanchez
Last time we looked back on how exhaust systems on vehicles came to be. At its most basic, a car’s exhaust system provides a way for spent gases to safely exit the vehicle and as such, require nothing more complicated than having connecting pipes, with one end bolted to the exhaust ports of the engine block while the other end opening just behind the under-body.
But as much as the internal combustion engine is a marvel of modern engineering, it is not without its flaws. In this article, we take a look at how the exhaust system has been purposed to address some of these flaws and further making the automobile a suitable everyday transport
From Vrooom to Purrrr...
Firearms and automobiles have a lot in common, not the least being the favorite projections of phallic compensation for men. Freudian jabs aside, guns and cars both use the explosive energy of fuel to create powerful mechanical forces. Exploding gun powder propel a bullet forward, combusting compressed air and fuel pushes down the pistons that drive the crank.
Both also create deafening sounds when in operation. Imagine the noise of unloading a few hundred rounds of bullets a minute and you have yourself an idling engine. Such noise is more at home in an 80’s action movie than a quiet neighborhood.
But right before the 1900’s a prolific British inventor and gunsmith developed and patented a design that suppressed the sound of a firing gun. This design principle later found application for the internal combustion engine, with two Indiana brothers who were pioneering American automobile designers receiving the patent on the muffler.
Stuff in the Muff.
The muffler has a simple but ingenious way of attenuating engine sounds. The insides of a muffler is divided into several resonating chambers, each connected to the other by sections of tubes. The metal pipe carrying exhaust gases (and effectively sound energy) from the engine terminates within one of the chambers within the muffler. Then through perforations on the pipe walls, hot exhaust gases flow out into one chamber, and from there, flow through other chambers through the connecting tubes until the gas finally finds the exit tube to the tailpipe. Gas being a fluid, can flow through tubes and chambers. Sound on the other hand, cannot. It can only radiate through a medium and owing to the internal structure of the muffler - it is effectively contained.
If you’ve ever been to the races, like the drag strip or the local track - where sensible sound levels are the last thing in anyone’s mind - you’ll know how loud the internal combustion engine can be. But without the muffler, society we’ll probably have a less enamored relationship with the modern car. So we can thank the lowly muffler for turning our raging rides into prim and proper little beasts.
We’ll talk about yet another flaw of the internal combustion engine, a flaw that’s a very pressing concern in the modern age: that the engine is a major contributor of air pollution, and we’ll see how the exhaust system plays an important role in addressing this.