Seemingly, starting a car is all about inserting the key and turning it. But do you really know how an engine works in a car or a motorcycle? The whole process of combustion goes on inside the hood with so many other parts that work to power the engine and maintain its efficacy. Apart from a few minor differences, the engine of a car and a motorcycle works in the same way.
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Video: How a car engine works?
Let us understand the basic parts of an engine and how it works.
Engines used in vehicles today are all internal combustion engines. The whole idea of combustion is to move the gasoline that, in turn, moves the car. Gasoline is set in motion by burning it inside the engine. Therefore, it is termed an internal combustion engine.
The engine works with the principle that burning fuel in a small and confined space releases energy. The released energy can be used for various purposes, one of which is running a car. Such explosions occur about a hundred times in a car per minute. The large amount of energy produced due to the explosions is used to propel the car.
Parts of an Engine
Here is a detail of all the parts that work together to run a car’s engine.
Valves: There are two valves: intake and exhaust valves. The intake valve lets the mixture of air and fuel in, and the exhaust valve makes way for the exhaust to go out after combustion. Both the valves stay closed during the compression and combustion stage.
Camshafts: The intake and exhaust camshafts are responsible for driving the valves. The camshafts are moved by the cam itself.
Spark Plug: The most important part; the spark plug creates a spark that ignites the fuel to allow the combustion.
Crank Shaft: Conversion of linear motion of the piston to rotational motion is done by the crankshaft.
Sump: Surrounding the crankshaft is a sump, which contains some oil that gets collected at its bottom.
Piston: Expansion of compressed air push down the pistons. As a result, the crankshaft turns.
Piston Rods: Also known as connecting rods, act as a link between the piston and the crankshaft. It is capable of moving at both ends so that it’s easier to move at different angles when the piston moves.
Piston Rings: These rings act as a seal that has a very important role. They create a barrier between the inner edge of the cylinder and the outer edge of the piston that is beneficial in preventing the fuel mixture and exhaust from leaking during the compression and combustion stage.
Four-stroke Combustion Cycle
A gasoline fuel engine works in a four-stroke combustion cycle that sets the gasoline in motion. These four strokes include intake, compression, combustion, and exhaust.
The crankshaft is linked to the piston by the piston (connecting) rods that plays the most important part in the whole combustion cycle. This is what happens during each phase of this cycle:
Intake: This step starts from the top. During it, the intake valve opens, and the piston moves down. As the valve opens, it allows the air mixed with the gasoline to enter.
Compression: Once the gasoline is inside, the piston moves back in the upward direction to compress the fuel and air mixture. This confined space is significant in making a more powerful explosion.
Combustion: On reaching the topmost part of the stroke, the spark plug plays its role by creating a spark that ignites the fuel. As a result, it explodes. This powerful explosion forces the piston down.
Exhaust: As soon as the piston makes it to the bottom of the stroke, the exhaust valve opens, allowing the exhaust to move outside, which was produced due to combustion. This waste gas reaches the catalytic converter to get cleaned, after which it moves out of the car through the tailpipe.
These four steps make one complete cycle. After a cycle ends, the engine gets ready to let in a mixture of fuel and gas for the next cycle.
Difference between Car and Motorcycle Engine
The basic principle, parts, and working of car and motorcycles engines are completely similar. Both the vehicles have internal combustion engines. Then what set them apart? Let us look over the differences.
A car is a heavier vehicle that needs more energy to move. Therefore, car engines are comparatively bigger that work five times more than a motorbike’s engine. Also, the engine of the motorcycle is compactly built to place in the confined space. This compact engine is enough to power low-weight vehicles like motorbikes.
Motorbikes run at high revolutions per minute (RPM) compared to cars. More revolutions mean more friction and thus a hotter engine. The temperature rises faster in motorcycles. As a result, they wear down quickly. In order to reduce friction, engine oils are used. Since both the car and motorcycle rotates at different RPMs, they need different engine oils to run efficiently.
Torque and Horsepower
How much torque an engine produces depends upon the bore and stroke of a piston. The circumference of a piston is its bore that determines the speed. At the same time, stroke is the horizontal length traveled by a piston. Stroke tells about the torque.
Since cars are heavyweight, they need more torque to move. Therefore, cars’ engines have a longer stroke and a small bore. On the other hand, the torque produced in motorcycles is less due to smaller strokes.
Cars and motorcycles have similar engines that run on the same principle. The spark ignites the gas that produces energy, which is used to propel a car or a motorbike. This internal combustion engine uses gasoline to keep it in motion so that the car can move. These engines are used in every vehicle today.
In contrast, we have external combustion engines in which combustion occurs in an external source. These engines are not in used in vehicles nowadays.
Image credit: Cars24