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Summary
  • A cylinder in an engine is where combustion happens to generate the power necessary to make the car move.
  • Common types of cylinder engines include three-, four-, and six-cylinder engines. The number of cylinders usually affects the amount of power an engine produces, but modern engines with fewer cylinders sometimes produce more power than older engines with more cylinders.
  • Bad spark plugs, faulty fuel injectors, and corrosion can cause damage to an engine cylinder. Engine misfires or overheating, lower fuel efficiency, and white or black exhaust smoke are symptoms of a damaged engine cylinder.

The engine is the beating heart of any vehicle. It’s what drives the rest of the vehicle’s components, from the alternator to the wheels. Cylinders, in turn, are what drive the engine. It is where combustion happens to generate the power necessary to move the car. Each cylinder contains an inlet valve, an exhaust valve, a spark plug, and a piston.

How Engine Cylinders Work

The cylinders are actually the round sleeves that are part of the block, and it’s in these sleeves that the pistons travel up and down. But typically the term “cylinder” is used to include the pistons, their bores, and the valves.

The pistons in the cylinders attach to the vehicle’s crankshaft via very strong “connecting rods” with one attached to each piston by means of a “wrist pin.”

The lower end of the rod is connected to one of the journals on the engine’s crankshaft with laminated bearings that receive pressurized lube oil. 

The crankshaft has one or more journals. There is one journal for each piston and connecting rod. The crankshaft, when turned by the action of the pistons and rods, transfers power through the transmission to the driveline and the wheels. 

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The engine’s torque is greatly multiplied by the driveline.

The Four Strokes in a Cycle

There are four strokes in each cycle, but only one of the four strokes produces power. The other three strokes are driven by the crankshaft, partially by inertia and partially by the action of the other cylinders, which fire at evenly spaced intervals. It takes 720 degrees of crankshaft rotation for one piston to complete a full four-stroke cycle.

There are four strokes in each combustion cycle, but only one of the four strokes produces power. The other three strokes are driven by the crankshaft, partially by inertia and partially by the action of the other cylinders, which fire at evenly spaced intervals. It takes 720 degrees of crankshaft rotation for one piston to complete a full four-stroke cycle.

Richard McCuistian, ASE Certified Master Automobile Technician

The beginning (first) stroke is the intake stroke, where the intake valve is opening and the piston is beginning its downward movement.

When the piston reaches the bottom of its travel, the intake valve has closed, and the compression (second) stroke begins, with the piston traveling up and squeezing the air-fuel mixture.

Just before the top of the compression stroke, the spark event occurs so that the oxygen and hydrocarbon fuel unite (burn) to form harmless CO2, which is what we and other animals breathe out.

This “burn” happens early enough that it reaches its peak pressure at just the right time to superheat (over 2000 degrees F) the inert nitrogen that makes up 78% of the earth’s atmosphere. As the superheated nitrogen expands when the piston begins its power (third) stroke so that as it travels downward, it forces the piston and its respective rod to rotate the crankshaft.

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The piston reaches the bottom of its third stroke and begins its exhaust (fourth) stroke as the exhaust valve opens and the other firing cylinders drive the piston back up in its cylinder sleeve to push the exhaust gas out through the open exhaust valve.

But right before the exhaust valve opens, just as the piston is reaching the top of its travel again, the intake valve begins to open, which purges any remaining exhaust from the small area above the piston. Then the whole cycle repeats. Every cylinder does this over and over in an order specific to the engine, and the spark that triggers each combustion event is  carefully timed (via the spark) for optimum power and efficiency.

Common Types of Cylinder Engines

There are different engine layouts commonly used in most vehicles, and they usually depend on how the cylinders are arranged and the number of cylinders. The number of cylinders typically indicates how much power an engine can produce, but this doesn’t always hold true when comparing older engines to modern engines. Technological advancements have increased engine power outputs as a whole, so modern engines with fewer cylinders can now match older engines with more cylinders.

For now, let’s take a look at a few common engine types.

Three-Cylinder Engines

Three-cylinder engines have an odd firing sequence and make a gurgling sound as they vibrate. You’ll often find them in compact SUVs and hatchbacks. They’re lighter and more fuel-efficient than the other engines on this list, but they’re also less powerful.

Four-Cylinder Engines

Four-cylinder inline engines are the most common engine type. You’ll find them in most passenger vehicles. They’re very fuel efficient and produce low emissions. However, they’re usually less powerful than six-cylinder and eight-cylinder engines.

Six-Cylinder Engines

More power-hungry vehicles like sports cars and heavy-duty trucks use six-cylinder engines. These engines make a distinguished high-pitched sound while running and are often paired with superchargers and turbochargers for even more power. They can have an inline or V layout depending on the manufacturer.

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Eight-Cylinder Engines

Eight-cylinder V-engines (V8’s) are the most common engines in the US. They’re incredibly powerful and tend to last longer than six-cylinder engines. On daily drives, eight-cylinder engines don’t need to work as hard as smaller engines due to their increased size and power output. However, eight-cylinder engines do use up more gas to account for these advantages.

Picking an engine type for your vehicle will come down to what you’re looking for. If you want maximum fuel efficiency, it’s best to invest in a three- or four-cylinder engine. If you’re ultimately after power, go for the eight-cylinder engine.

Damaged Cylinder Causes and Symptoms

A damaged car engine cylinder can cause a number of problems. Because of how many components make up a fully-functioning engine cylinder, there are a number of possible causes behind a faulty cylinder. For instance, a bad spark plug or fuel injector can easily cause problems during the power stroke. Corroded cylinder components or an overheating engine can also contribute to signs of a damaged engine cylinder.

If your engine’s cylinder is malfunctioning, you can expect the following symptoms:

Now that you know what the cylinders in a car are for, an engine’s specifications should be much more decipherable at a glance.

About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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