Have you ever wondered how your car is able to convert gasoline into the power needed to move? The engine is the heart of your vehicle, and it is responsible for converting fuel into the energy that propels your car down the road. But how exactly does a car engine work?
What is Car Engine?
A car engine is a complex machine built to convert fuel into mechanical energy through a series of controlled explosions, or combustions, in the cylinders. These explosions drive the pistons, which in turn rotate the crankshaft, generating the rotary motion that powers the wheels of the car.
An internal combustion engine is commonly found in cars and is made up of several key parts, including cylinders, pistons, crankshaft, and camshaft. The engine is composed of two main parts: the cylinder block and the cylinder head.
The cylinder block is the lower, heavier section of the engine and acts as a casing for the main moving parts. The cylinder head is a detachable upper cover that contains valve-controlled passages through which the air and fuel mixture enters the cylinders and others through which the gases produced by combustion are expelled.
The cylinder block also houses the crankshaft, which converts the reciprocating motion of the pistons into rotary motion at the crankshaft. This rotary motion is then used to turn the wheels of the car. The cylinder block also often houses the camshaft, which operates mechanisms that open and close the valves in the cylinder head. In some cases, the camshaft is located in the head or mounted above it.
There are two main types of car engines: the gasoline engine and the diesel engine. Gasoline engines use a spark to ignite a mixture of fuel and air, while diesel engines rely on compression to heat the air and ignite the fuel. Both types of engines have their own set of advantages and disadvantages, but both are designed to convert fuel into energy that can be used to power a car.
Car engines have come a long way in recent years, with advancements in technology leading to more efficient and powerful engines. Electric and hybrid engines are becoming increasingly popular, as they offer improved fuel economy and lower emissions.
How Does An Engine Work In a Car?
Specifically, an internal combustion engine is a heat engine in that it converts energy from the heat of burning gasoline into mechanical work, or torque. That torque is applied to the wheels to make the car move.
The engine consists of a fixed cylinder and a moving piston. The expanding combustion gases push the piston, which in turn rotates the crankshaft. Ultimately, through a system of gears in the powertrain, this motion drives the vehicle’s wheels.
Two types of internal combustion engines are currently manufactured: the spark-ignition gasoline engine and the compression-ignition diesel engine. Most of these are four-stroke engines, meaning it takes four piston strokes to complete a cycle. The cycle includes four distinct processes: intake, compression, combustion and power stroke, and exhaust.
The basic components of a car engine include cylinders, pistons, and valves. The cylinders are the hollow chambers where the combustion process takes place. The pistons are the cylindrical parts that move up and down inside the cylinders, and the valves control the flow of air and fuel into the cylinders, as well as the exhaust gases out of the cylinders.
The combustion process in a car engine starts with the intake of air and fuel into the cylinders. The air and fuel are mixed together in a precise ratio, and then they are compressed by the pistons. Next, a spark is created by the spark plugs, which ignite the mixture, causing it to combust.
The combustion process creates a high-pressure force that pushes the pistons down, which in turn rotates the crankshaft. The crankshaft is connected to the car’s transmission, which sends the power to the wheels to move the vehicle.
As the pistons move up and down, the valves open and close to allow the air and fuel in, and the exhaust gases out. The exhaust gases then flow through the exhaust system and out of the car through the tailpipe.
A car engine is a complex machine with many moving parts, but at its core, it converts fuel into energy to power the vehicle. And with the current developments in technology, there are also other types of engines like electric engines, hybrid engines, and hydrogen fuel cell engines, which work on different principles but all serve the same purpose, which is to power the vehicle.
The Four Strokes of a Four-Stroke Engine
The engine does this by following a four-stroke cycle, which consists of the intake stroke, compression stroke, power stroke, and exhaust stroke.
1. Intake Stroke.
The intake stroke starts at the “Top Dead Center” (TDC), where the piston is at the top of the cylinder. As the piston moves down the cylinder, it creates a vacuum, and the intake valve opens, allowing air to be sucked into the cylinder.
In carburetted engines and port and throttle body injected motors, the fuel comes in with the air. In direct-injected motors, the fuel is squirted directly into the cylinder.
2. Compression Stroke.
The compression stroke begins when the piston reaches the “Bottom Dead Center” (BDC). The intake and exhaust valves are both closed, and the fuel and air mixture is compressed by the piston into the combustion chamber.
The compression ratio is the volume of the cylinder plus the combustion chamber compared to the volume of just the combustion chamber. This ratio can be anywhere from 8:1 to 12:1 or more in some race engines.
Compressing the mixture greatly increases the amount of power produced by combustion, but the compression itself produces heat, which can cause detonation or pre-ignition.
3. Power Stroke.
The power stroke is where the engine produces power. The spark plug fires, igniting the mixture, as the piston is at the top of the stroke. The resultant explosion moves the piston rapidly back down the cylinder, turning the crankshaft, and making the car go.
In a diesel engine, there is no spark, the mixture just spontaneously ignites at the right moment due to the heat of compression. In a single-cylinder engine, at idle, you can practically hear each individual explosion.
4. Exhaust Stroke.
The exhaust stroke begins when the piston moves back up the cylinder due to the momentum produced during the power stroke and the weight of the flywheel (in a single-cylinder motor), or due to the firing of other cylinders.
The exhaust valve opens, and instead of compressing the burned gases, they are pushed out into the exhaust port. As the piston gets close to TDC again, the exhaust valve starts to close, and the intake starts to open, for a small period called “overlap” where the escaping exhaust creates suction that helps pull air in via the intake valve opening.
The cycle then starts again, with the piston moving down on another intake stroke.
Main Parts of a Car Engine
The different parts that make up your car’s engine consist of: the engine block (cylinder block), the combustion chamber, the cylinder head, pistons, the crankshaft, the camshaft, the timing chain, the valve train, valves, the rocker’s arms, pushrods/lifters, fuel injectors, and spark plugs.
1. Engine Block.
The engine block is the central part of a car engine. It is typically made of aluminum or iron and serves as the foundation for the other components of the engine. The engine block contains several holes called cylinders, which house the pistons.
These holes also provide pathways for water and oil to flow through, which helps to cool and lubricate the engine. The oil pathways are usually narrower than the water flow paths.
Additionally, the engine block houses other important components such as the crankshaft, camshaft, and between four and twelve cylinders. Depending on the vehicle, these cylinders may be arranged in a line (known as an inline engine), in a flat configuration, or in a V-shape.
Pistons are cylindrical devices with a flat surface on top. They play a crucial role in the car engine by transferring energy created from combustion to the crankshaft. This energy propels the vehicle.
As the crankshaft rotates, the pistons travel up and down within the cylinder twice during each rotation. For example, in an engine that rotates at 1250 RPM, the pistons will travel up and down 2500 times per minute.
Inside the piston, there are piston rings that are designed to help create compression and reduce the friction caused by the constant rubbing of the cylinder. These rings seal the gap between the piston and the cylinder wall, ensuring that the combustion gases are contained within the cylinder and that the engine runs smoothly.
3. Combustion Chamber
The combustion chamber is a critical part of a car engine, where the energy is transformed in the combustion process. This is the area where the fuel, air, and electricity are combined and ignited to create the energy that powers the engine.
The combustion process releases a large amount of energy in the form of heat and pressure. This energy is used to drive the pistons up and down, which in turn powers the crankshaft and eventually the wheels of the car. The movement of the pistons is what gives the car the power to move.
The crankshaft is a crucial part of a car engine that converts the reciprocating motion of the pistons into rotational motion. It is located in the lower section of the engine block and is supported by bearings called crankshaft journals.
The crankshaft is connected to the pistons through a connecting rod, which converts the up and down motion of the pistons into a reciprocal motion at engine speed. This reciprocal motion is then used to power the wheels of the vehicle.
The camshaft is another important part of the engine that regulates the timing of the opening and closing of valves. The camshaft’s location varies from vehicle to vehicle, it can either be located within the engine block or in the cylinder heads.
Many modern vehicles have them in the cylinder heads, also known as Dual Overhead Camshaft (DOHC) or Single Overhead Camshaft (SOHC), and supported by a sequence of bearings that are lubricated in oil for longevity.
The camshaft takes the rotary motion from the crankshaft and converts it into an up-and-down motion. This motion is then used to control the movement of the lifters, pushrods, rockers, and valves.
This is important for the engine’s proper functioning, as it ensures that the correct amount of air and fuel enters the combustion chamber at the correct time, leading to efficient combustion and power production.
6. Cylinder Head.
The cylinder head is a critical part of a car engine. It is attached to the engine block through cylinder bolts and is sealed with the head gasket. The cylinder head contains several important items that help control the flow of air and fuel into the engine and the removal of exhaust gases.
These items include valve springs, valves, lifters, pushrods, rockers, and camshafts. The valve springs and valves control the flow of air into the engine during the intake stroke and the removal of exhaust gases during the exhaust stroke.
The lifters, pushrods, and rockers are used to operate the valves and keep them in sync with the engine’s movement. The camshaft is a shaft that rotates inside the engine, and it controls the timing of the valves and lifters.
7. Timing Belt or Chain.
The timing belt or chain is another critical component of an internal combustion engine. It is responsible for synchronizing the camshaft and crankshaft to ensure the precise timing required for the engine to run properly.
The timing belt is made of heavy-duty rubber with cogs that grasp the pulleys from the camshaft and crankshaft. The timing chain, similar to a bicycle chain, wraps around pulleys with teeth.
Different Types of Engine Layouts
Simply put, an engine layout refers to the arrangement and number of cylinders in an engine. There are many types of engine assemblies, but three types of car engine assemblies are commonly used.
Straight or Inline Engine Layout
The Straight or Inline engine layout is the most commonly used engine layout in cars today. As the name suggests, the cylinders in this layout are placed vertically in line, one behind the other. This layout is known for its simplicity and ease of manufacturing and installation, making it an affordable option for car manufacturers.
When the engine is placed parallel to the car, it is known as a Straight layout. This layout is often seen in luxury sedans, such as those from BMW or Mercedes, as it allows for more cylinders and therefore more power. However, due to its larger size, it is not as commonly used in smaller vehicles.
On the other hand, when the engine is placed perpendicular to the car, it is known as an Inline layout. This layout is more compact and allows for other car components to be placed around it, making it a popular choice for entry-level family cars such as hatchbacks.
Flat Engine Layout
A Flat engine, also known as a Boxer engine, is a type of internal combustion engine that has its cylinders placed horizontally. Unlike a straight engine, which has its cylinders arranged vertically, the Flat engine has a unique design where the pistons move in a horizontal motion, resembling the movement of a boxer punching their gloves before a fight.
This design results in a balanced engine with low vibrations due to the force created by the piston movement.
One of the advantages of the Flat engine is its low center of mass, which improves the handling of the car. Additionally, due to the large surface area of the cylinders, they are air-cooled evenly, resulting in better cooling efficiency.
However, the Flat engine is more expensive to manufacture than a straight engine and its wide shape is not preferred by many automotive manufacturers. Currently, Porsche and Subaru are the only carmakers that feature the boxer engine in their lineups.
The V-engine, also known as a V-cylinder engine, is a popular engine layout that is characterized by its V-shaped cylinder arrangement. The cylinder banks, which are the chambers in which the pistons move, are arranged in a V shape when viewed from the front of the engine.
This allows for more cylinders to be accommodated in a smaller space, which means that the engine can produce more power while still maintaining a sleek and aesthetic look for the vehicle.
One of the main advantages of the V-engine is that it can produce more power than other engine layouts, such as the straight engine. This is because all of the pistons achieve their power stroke at a closer time interval, which results in more efficient combustion and more power output.
However, the V-engine is also more prone to vibrations than a straight engine and is more complicated to build, which can make it more expensive to repair.
Despite these challenges, many high-performance car manufacturers such as Ferrari, Alfa Romeo, and Mercedes Benz opt for the V-engine layout due to its compact size and high-power output capabilities.
This engine layout is commonly used in sports cars and high-performance vehicles because of its ability to deliver high power and torque while still maintaining a sleek and sporty design.
Car Engine Cylinder Configurations
In the past, the number of cylinders in a vehicle’s engine was a key indicator of its power and performance. A vehicle with more cylinders typically had more power and better performance than one with fewer cylinders.
However, today’s technology has made it possible for smaller engines to produce similar or even higher outputs than larger engines. This is due to the use of high-tech fuel injection systems and other efficient engine components that allow smaller engines to perform at a higher level.
There are several types of configurations which are listed below.
A twin-cylinder engine is a type of internal combustion engine that has two cylinders arranged in a V-shape or in-line configuration. This configuration is relatively simple and compact compared to other engine designs and is often used in small and lightweight vehicles such as motorcycles.
The twin-cylinder engine is known for its low power output, which is why it is not commonly found in cars. However, it is a popular choice for motorcycles because it provides a balance of power and fuel efficiency, and can be easily packaged into a small space.
One example of a motorcycle that uses a twin-cylinder engine is the Royal Enfield Interceptor 650. Another example is the Kawasaki Ninja 300. On cars, the twin-cylinder engine can be found in the Tata Nano, which is a compact car designed for the Indian market. The Tata Nano is powered by a small 624cc twin-cylinder engine that provides low power output but decent fuel efficiency.
Three-cylinder engines are known for their unique, gurgle-like sound due to the odd firing sequence and vibration they produce. Despite this, they are more powerful than two-cylinder engines and with the inclusion of turbochargers, they can give increased power output while maintaining efficiency.
These engines are commonly used in hatchbacks and compact SUVs like the Maruti Suzuki Celerio and the Tata Nexon.
Four-cylinder engines are the most commonly used configuration for cars due to their increased power and efficiency. They are mostly found with an inline layout, which when combined with a turbocharger, can make a powerful engine.
Cars like the Honda City, Maruti Suzuki Swift, and Hyundai Elantra are examples of cars that use the 4-cylinder configuration.
Five-cylinder engines are a less common configuration and are mostly seen in luxury car manufacturers like Audi and Volvo. Due to the odd number of cylinders, the 5-cylinder configuration emits a peculiar sound, known as warbling.
These engines are powerful, but less common due to their complexity and the cost associated with manufacturing them.
The six-cylinder engine configuration is a common choice in sports cars and luxury sedans. It is known for its high-pitched sound, and can be designed with a straight layout or a V-engine layout depending on the car.
Cars like the BMW 5-Series and Mercedes Benz C-Class use the 6-cylinder configuration, which is paired with a turbocharger or a supercharger to give them additional power.
Eight Cylinders and Above
The eight-cylinder configuration and above are mostly used in supercars and are typically designed in a V-engine layout. Cars like the Bugatti Chiron have a W16 engine, which is a 16-cylinder configuration in a W layout.
Other supercars like the Ferrari F8 Tributo and Lamborghini Aventador use a V8 and V12 configuration respectively. These engines are capable of high speeds and have tremendous torque, and their sounds vary from a roar to a high-pitched squeal, depending on the supercharger used.