How Much Do You Know about Auto Exhaust Systems?

AUTO

Steven Symes

6 Min Quiz

What is a "cat" in a car's exhaust system?

The cat or catalytic converter changes especially harmful gases in the exhaust to relatively harmless gases, using precious metals, which is why they cost a pretty penny to replace.

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What part of the exhaust system collects gases from the engine's cylinder head?

The exhaust manifold bolts to the cylinder head, creating an airtight seal so exhaust gases can flow from one to the other without anything leaking.

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An exhaust resonator has what job?

You can think of the resonator in your exhaust as a type of echo chamber. It's an essential element to quieting the exhaust, so if you chop it out and replace it with just piping, your exhaust will be louder.

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What is the front pipe?

The exhaust manifold's collectors connect to the different cylinder's exhaust pathways in the head, and those converge, channeling into the single pipe called the front pipe.

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What exhaust system component failure can trigger the check engine light?

Since the O2 sensor is an essential part of the emissions system for a car, when it fails that will trigger the dreaded check engine light, but a diagnostic will reveal the cause.

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What's the purpose of modifying or upgrading a vehicle's exhaust system?

Admittedly, most exhaust system upgrades don't result in a huge performance benefit by themselves, although they may be necessary for fully realizing the benefits of other modifications.

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What is a cat-back system for a car's exhaust?

Cat-back systems are one way to modify the stock exhaust on a car, since most tuners won't touch the catalytic converter, unless they're doing an especially aggressive build.

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What's usually the material of choice for exhaust components that will last a long time?

Stainless steel resists corrosion, an issue that plagues quite a few exhaust components since they're subjected to road salt and other corrosive factors, plus it's not too expensive.

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What kind of an exhaust note will an H-pipe typically produce?

An H-pipe mid-pipe gets its name for the striking resemblance it has to the letter "H." Not only will it make the exhaust note lower, it usually helps with low-end torque.

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If the exhaust system suddenly becomes louder, what could be the cause?

While the muffler might be the first place to check for a puncture or rust damage, you should also look at the pipes, since damage on those can have the same result.

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To seal connections between the different sections of the exhaust, what's used?

Without proper gaskets, exhaust gases would leak out of the different joints in the exhaust system and could potentially enter the car's interior.

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Where is the muffler always found in an exhaust system?

Believe it or not, the muffler on some cars isn't located at the very rear of the exhaust system, and sometimes it can be located near the catalytic converter, so there's really no rule on this one.

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What's one sign that the catalytic converter for a car is clogged?

Over time a catalytic converter can fill up with debris, which not only makes a strong burning smell, but it also cuts the engine power by quite a bit.

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What's the point of an exhaust cutout?

An exhaust cutout is essentially a Y-pipe where one end of the pipe is open and points toward the back of the vehicle. Mechanically or electronically moving a blocking flange will determine which way the exhaust gases flow, with the cutout pathway usually only used on tracks.

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What benefit does back pressure provide for performance?

Back pressure is never a good thing for engine power, despite what you might've heard in the past, which is why eliminating it is beneficial for performance.

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If you're sitting in a car with the door open and the engine running and hear a ticking coming from under the car, what's likely the issue?

Donut gaskets sit between different portions of the exhaust piping and other components on the underside of your vehicle, and when they fail, those components will click against each other.

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What is scavenging in an exhaust system?

If you think that exhaust gases flow at even rates through the exhaust system, the fact is that voids in the flow actually help pull exhaust gases out of the cylinders and into the system, which is scavenging, commonly confused with back pressure.

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What do bends in an exhaust system do?

The more bends in an exhaust system, the worse for performance, which is why you'll see exotic cars with almost completely straight exhausts for maximum power.

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What kind of an exhaust tone will you generally get from an X-pipe?

An X-pipe mid-pipe, which has the two pipes crossing in an X-pattern and connecting, will make your exhaust system overall louder and usually helps with top-end horsepower.

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What's the secondary benefit of the open exhaust pipes on a top fuel dragster?

While these short pipes that are bolted right onto the engine certainly allow for quick exhaust flow, they also produce downforce to hopefully keep the car from becoming airborne.

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What are straight pipes?

Straight pipe setups have zero restrictions, including a catalytic converter or mufflers. They're louder and the exhaust gases flow unobstructed, but it's usually illegal for street vehicles in most areas.

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What's the point of wrapping an exhaust system?

If you have an exhaust system that feeds a turbo system, having heat bleed out of the pipe walls isn't a good thing, but in most exhaust setups this modification isn't really necessary.

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Why do some pickup trucks have exhaust pipes that are bent to the side, in front of the back wheels?

One of the points of having a pickup truck is to tow stuff, and if the exhaust exits straight out of the back of the truck, that means it flows right into the trailer. This design prevents that.

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If there's a ticking sound coming from the engine compartment, what exhaust problem does a car have?

You might even think the ticking sounds like an old clock, but it's from an exhaust manifold that needs to be swapped out for something new.

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If a car has a Y-pipe, how many tailpipes will it feature?

Some V-6 cars come with a Y-pipe as a way to feed the two sets of collector pipes into a single catback system, which means a single tailpipe.

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What's inside a muffler?

Mufflers are designed to reduce the noise levels produced by the engine, but how they do that varies. They might contain tubes, baffled chambers, fiberglass, rock, wool, etc. as a way to deaden the sound.

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What's a header?

Tuners like to swap out the stock exhaust manifold for headers, which allow the exhaust gases to flow faster so the engine "breathes" better. The exact benefit varies by the car and design.

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What effect can a bad oxygen sensor have on your car?

The oxygen sensor provides information to the engine ECU, which uses that data to adjust the air-fuel mixture in the cylinders, so a bad sensor could result in too much fuel used.

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What forced induction setup can be powered by the exhaust system?

Turbocharger fins are spun up or spooled by exhaust gases as they flow through one part of the housing, which in turn draws in fresh air through another section.

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What does a catalytic converter need to be fully functional?

The catalytic converter is usually placed fairly close to the engine so it heats up quickly, but it can't get too hot or it will become damaged, so the engine will cool it off sometimes with an extra-rich air-fuel mix.

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What part of the engine controls the flow of exhaust gases?

Each cylinder has at least one exhaust valve. It opens after combustion, allowing the exhaust gases to flow out of the cylinder, into the head and then into the exhaust manifold.

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What important function do air gap pipes perform?

Air gap pipes fit over or next to certain lengths of the exhaust system. That extra layer of air shields the chassis from heat as well as keeping the noise level inside the cabin down.

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If installed on the rear, what does a Y-pipe make possible?

Some people like the sporty look of dual exhaust pipes, and a Y-pipe bolted to the back of an exhaust system will give them just that.

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How do the exhaust systems in hardcore off-roaders differ from others?

The exact design of various off-road oriented exhaust systems varies, but most place the muffler, resonator and catalytic converter as close to the chassis as possible to lessen the risk of damage when driving on a trail.

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How is the cat-back system connected to the car's chassis?

The cat-back system has hooks welded onto it. They fit on rubber hangers, which over time wear out and break. Fixing a sagging cat-back is a relatively inexpensive and simple job.

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About This Quiz

Don't get your pipes crossed, because this exhaust systems quiz is designed to create a little back pressure in your head. 

Most people only see the tailpipe and maybe the muffler in their exhaust system. They might realize it transports exhaust gases away from the car, but that's about the extent of their knowledge. If you've spent time underneath a car, you have more knowledge of exhausts than most people. What's even better is if you can draw a diagram with all the usual components in place. 

An exhaust system is a necessary part of any vehicle. Without them, we'd risk breathing dangerous gases produced by the engine, like carbon monoxide, which could flow right into the passenger compartment at any time. Instead, the exhaust system actually transforms the worst of the gases into less harmful combinations. It also transports the gases to the very end of the vehicle, where they can flow out and away from you and your loved ones. 

Do you have the layout and function of car exhaust systems down? Test your knowledge right now with this quiz! 

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