INTRODUCTION
Welcome back. Lask week, I introduced you to the vast world of automobiles, and we dove into the heart of the modern vehicle, the engine. We took at a look at the 4-stroke cycle, and how exactly the engine is able to turn gasoline into motion of the car. At the end of the article, I touched on turbocharging, which is an extremely common form of forced induction of the engine, used to make cars more efficient, and run better.
When the average individual takes a look at a car, they will be able to name many parts around and inside of the vehicle, but chances are, they may completely forget what’s happening under the car. Well today, we’re going to be transitioning from under the hood of the car to under the car itself! That’s right, the exhaust system. The exhaust system in an automobile is significant, and there are actually many parts to it, which all have different functions. With that said, let’s get right into it.
THE MANIFOLD
Once the engine completes one cycle of the 4-stroke, the burnt air-fuel mixture takes the form of a gas, and it is at this very point that the exhaust system comes into play. Depending on the amount of cylinders that the vehicle has, there may be different types of exhaust manifolds. The exhaust manifold is a bulky piece of steel or aluminum which essentially combines all the gas of all the cylinders into one pipe. Also located within or near this manifold is the Oxygen sensor, which is an important diagnostic tool, and helps technicians to see if a car is successfully keeping up with environmental regulations. Depending on the year of the vehicle, there may be even more sensors located here, because this is the place where the burnt exhaust gas first exists.
THE CATALYST
Moving forward (or should I say backward), the first large mechanism, or device, that we run into, is the “Catalytic Converter”. Now, just going by the name, one might assume the function of this significant piece of hardware. The job of the catalytic converter is imperative: to chemically change and filter out harmful gases produced by the engine, including but not limited to carbon monoxide, hydrocarbons, and sometimes even dangerous nitrogen oxides. Depending on the size of a vehicle, or simply the size of its engine, a vehicle may have only one “cat”, or it may have two (known as the secondary cat).
The need for catalytic converter is seemingly obvious, especially with today’s growing limitations when it comes to emissions. Funny thing is, the most stolen item at mechanics shops and garages tend to be catalytic converters, just because of how important they are to a vehicle, and their value due to the aforementioned functions.
THE MUFFLER
Mufflers come in all different shapes and sizes, and they do just what they sound like they do: muffle the sound of the gases coming out of the engine. Keep in mind, at this point, we are past the catalytic converter, and the gases have been cleared of harmful chemicals (for the most part). So, once the gases do pass the cat, they move through the exhaust piping (which is carrying all gases when they are not going through different exhaust devices), and they often go through at least 2 types of silencers before being released into the environment. Again, depending on the size, layout, and make of a vehicle, there may be more than more muffler present. Mufflers are relatively large in size when it comes to undercarriage parts, and they are also required by law in many places around the world (same with catalytic converters).
A “resonator” is another type of silencing device, and it works very similarly to a muffler, though its size is much smaller. A resonator mainly adjusts the tone of the sound coming out of the engine, and in many cars, it actually comes before the muffler(s).
PERFORMANCE
I just wanted to include this section because I am very much into sports and tuner cars, and one of the biggest modifications you will see in the world of tuner cars are exhaust modifications. Since the overall goal of the exhaust system of the average car is to make the sound quieter and limit emissions, it is not ideal for fast cars.
When the engine is burning fuel and putting out exhaust gas at high RPMs, the back pressure of gas is very high. Having a catalytic converter, resonator, and mufflers will not help that gas flow any faster or easier, which is the reason race cars, tuner cars, and supercars have very restrictive exhaust systems. For example, many aftermarket tuning companies offer products such as “high flow catalytic converters” or “catless downpipes”, which all serve to let that gas flow as quickly as possible, and get out of the car through the tailpipes fast. Additionally, tuners often delete their mufflers/resonators/etc. so as to allow the flow of gas, which of course, comes with louder noise. MUCH, louder noise. For car enthusiasts, nothing beats the smell of burnt gasoline and a screaming exhaust. Ah.
Anyhow, these additions (or deletions, rather) do come with their cons. First and foremost, damage to the environment. Without any restriction straight from the engine, chemicals like carbon monoxide and other hydrocarbons and put into the atmosphere, which can cause environmental degradation of many types. Second, these modifications aren’t exactly legal. Directly taking out these parts may cause you to fail inspection, or get in trouble with the police if you’re driving down the road. That’s why many aftermarket companies have innovatively come up with ways to get that unrestricted performance with actual, physical mufflers and cats. This way, you will pass inspection, and the car will be legal.
When it comes to building a tuner car, however, there is much more that goes into making a car run quicker. The exhaust is just one of the important systems which can be freed through unrestrictive products.
CONCLUSION
The cars we see everyday all have exhaust systems. Though we never really lay our eyes on this system, it is doing one of the most important jobs in society by protecting our planet. Modifying the exhaust of a vehicle will come with performance and sound benefits, but environmental (and potentially legal) issues. Of course, if you see a Tesla going down the road, you can completely ignore everything that you learned in this article. Not really, but the magic of the electric vehicle has allowed for the complete elimination of the exhaust system (no engine, no exhaust). This is going to be the perfect transition to next week’s topic: Electric Vehicles! I am looking forward to it, and I hope you all are as well. Thanks for reading today, and I’ll see you next time.
Excite The Mind 