How Car Engine works

How Engine Basically Works

Usually people don't know how what they have under their cars Hood, what is a 12 valve engine, 1.6 liter engine, what is DOHC or SOHC etc. I also came across some people who did not even knew what mpg or km/hr meant. So i am creating this page so that you folks can have a increase in your knowledge and dont worry i am going to keep it as simple as possible for your better understanding :D

So there are many different types of engines with different technologies. This page will tell you how does a internal combustion engine works. This type of engine is used in most of the cars now a days.

Internal  Combustion Engine

As you all know you cannot burn anything without oxygen or air, so if you want to burn fuel inside the engine, the engine should be able to access some air or oxygen. And the more efficiently the engine breathes, the more efficient will be the performance of the car.

Basic engine parts

There are many engine parts but the ones you should know for now are as follows

1. Spark plug ( the plug that sparks and ignites the gas inside the cylinder )
2. Valves ( the valves let the air and exhaust inside and outside )
3. Piston ( the cylinder which moves up and down )
4. Crankshaft ( the crankshaft turns the up and down motion of the piston in to a circular motion )

How Engine works

How engine works is a cycle of 4 step that is repeated again and again to keep the car moving or engine running invented by Nikolaus Otto. This cycle is also known as Otto cycle.

1. Intake (cylinder moves down)
2. Compression (cylinder moves up)
3. Combustion (cylinder pushed down)
4. Exhaust (cylinder moves up)

I animation on the right side is taken from the website: Wikipedia for better explanation.

1. Intake

The intake valve opens, which lets the air inside to be mixed with gasoline, while the piston moves down.

2. Compression

The piston moves up compressing the air and gasoline mixture, Compression makes the explosion more powerful.

3. Combustion

As the piston reaches the top, the spark plug emits a spark that ignites the compressed mixture of air and gasoline which ends up making an explosion. The explosion then forces the piston down.

4. Exhaust

Once the piston reaches down to its limit, the exhaust valve opens which lets the exhaust or burned air fumes to leave the cylinder.

This is only one cycle which when ends, the process starts all over again and keeps on going until the engine is turned off. 

The pistons produce a linear motion which is converted into a rotational  motion by the crankshaft, which helps us moving the wheels of the car.

 Explaining how does the Camshaft operates is very lengthy which is why i will explain it in my next post. For now let me tell you what DOHC and SOHC means. You should have heard these terms from people talking about their cars and engines (for example this car has a SOHC 2 cylinder 800cc engine). These terms are basically the short forms of double overhead cam and single overhead cam which describes the layout of the engine which i will tell you in my next post.

Important stuff you should know

Compression ratio

What is compression ratio? It is the ratio between the total volume of the combustion chamber and cylinder, when the piston is at the bottom of its stroke and when it is at the top. With higher compression ratio you can give you more power.

Engine displacement (Bore and Stroke)

You must have heard the terms 1.5 liter engine ,2.0 liter engine etc. What does it actually means? 

It is the total internal size of the engine measured by multiplying the cylinder bore and the length of cylinder stroke which is further multiplied with number of cylinders and it is expressed in liters.

Valves 

You must have read on your car engine 12 valve, 24 valve etc So you must be curious that what is valve? The valves help the engine to breath, there are two types of valves. Both of them are explained above briefly. So 12 valve means that engine may have 6 intake and 6 exhaust valves but it does not means all engines have 1 intake and 1 exhaust valve. Some engines have more than one intake or exhaust valves for a single cylinder so that the engine could breath better. In short, the more the valves the better the engine performs.

So this is how engine is powered. In my next post i will tell you how the camshaft converts its motion and ends up moving the car. I hope i have have increased your knowledge and if you have any questions you can comment below, i will be happy to help.