A Beginner’s Guide to Internal Combustion Engine: Working Principles, DIY Builds, and Common Uses

You know the wheel was developed in 3500 B.C in the Mesopotamian era, and till the early 1800s, animal carts were the only mode of transportation for about 5500+ years. In the early 1800s, we saw the development of the steam engine, and by the late 1800’s we saw the Internal Combustion engine ( ICE ). 

And in just 200 years, this engine has enabled us to increase our travel speed from 5-8 km/hr to thousands of km/hr. So, if you want to know more about this incredible human invention, keep reading!

What’s an Internal Combustion Engine? 

“As the name suggests, all the combustion process happens inside the Engine, so it is called an Internal combustion engine.”

In the early days, when Étienne Lenoir built the first ICE engine, it lacked the compression cycle, so it wasn’t much fuel efficient. But later, Nikolaus Otto introduced a theoretical cycle which became the basis of all internal combustion engines ( wankel & piston ones).

The Nikolaus Otto cycle is known by many names, such as the Beau de Rochas cycle, or Otto cycle, which is explained as;

Step 1) Intake - In this step, fuel & air vapours are injected into the cylinder.

Step 2) Compression - the piston moves up, compressing the fuel & air mixture ( which is already present in the cylinder ). This step creates high pressure, temperature, and concentration needed for combustion.

Step 3) Combustion - Now, with the help of a spark plug ( or high pressure ), the fuel is ignited, creating a boom with high pressure which pushes the piston downward, which in return rotates the crankshaft.

Step 4) Exhaust - The remaining residual gas is forced outside the cylinder.

It is important to note that besides the Otto cycle, there is the Brayton Cycle, which is basically used for jet engines and has a bit different function, which we will discuss below in the ICE engine categories, but the concept is almost the same as above Otto cycle.  

In contrast, there are external combustion engines, in which combustion is done outside the engine. For example, in a steam engine, the water is heated in a boiler using fire outside the engine, which produces high-pressure steam, which then powers the engine.

• Brief history

In the 19th century, Étienne Lenoir (Belgium/France) made one of the earliest and most practical gas engines in 1860. However, it was a single-stroke of non-compression type, which was not efficient at all. 

However, after some years, Nikolaus Otto ( Germany ) improved on these designs and came up with the more efficient four-stroke engine, which facilitated most modern engines in 1876. 

Soon thereafter,  Sir Dugald Clerk (Scotland) introduced the first ever two-stroke engine in 1879, which was the first to work successfully and took up much less space. 

Ultimately, Rudolf Diesel (Germany) in 1897 developed the diesel engine, which provided enhanced power as well as fuel efficiency. 

All of the above-mentioned engines are piston engines. However, in 1957, Felix Wankel developed a rotary type of internal combustion engine, which came to be known as the Wankel engine. 

Overview of Types Of Internal Combustion Engine 

As we go through history, there are mainly 3 types of Internal Combustion engines based on their working design;

Type 1: Wankel /Rotatory Engine: Has a circular cylinder in which a rotor revolves to create power.

Type 2: Piston Engine: Has a cylinder design in which the piston moves up & down to create power. As we further go, the piston engine can be classified into 2 types based on how many strokes it completes in one power stroke.

Type 3: Brayton/turbine Engines: There is a setup of turbines & propellers in which there is continuous combustion.

As we go further, the piston-type engine can be further classified based on the type of fuel they use, ignition methods, air intake methods, and hybrid systems.

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Type 1) Wankel /Rotatory Engine

As the name suggests, the Wankel or rotatory engine has a triangular rotor instead of pistons, and it spins inside an oval-shaped housing. This design allows the rotor to perform intake, compression, combustion, and exhaust in one go, making the whole process smooth.

Why they fail: Wankel or Rotary engines are no doubt compact, lightweight, and smooth-running. But they had major drawbacks such as low fuel efficiency, higher emissions, and short lifespan, making them a failure. 

Uses: Wankel engines are used in a few cars, such as the Mazda RX-7 and RX-8. They were also used in a handful of bikes, snowmobiles, drones, and aircraft. But these days, you can rarely find them in any new vehicle due to strict environmental policies ( they have higher emissions ). 

Type 2) Piston Engine

“As the name suggests, these engines have pistons that move the crankshaft and generate power.”

All of us know Piston engines as they are used in every land, sea, and aerial vehicle. Before learning the working of the Piston engine, let us learn its basic parts.

• Cylinder – a chamber where combustion happens

• Piston – a round block that moves up and down inside the cylinder

• Connecting rod – links the piston to the crankshaft

• Crankshaft – a long rod that converts piston motion into rotation

• Valves – control air-fuel intake and exhaust

• Spark plug – ignites the air-fuel mixture (in petrol engines)

• Camshaft – opens and closes the valves in sync

Subtypes of Piston Engine: 2- Stroke Vs. 4- Stroke ICE Working Mechanism

Before discussing 2 or 4 stroke, let us first study what a stroke is;

“In an engine, when the piston moves from the highest ( TDC ) to the lowest ( BDC ) cylinder points or from the lowest to the highest, it is called a stroke.”

So, based on the number of strokes to complete a full internal combustion engine cycle ( intake, compression, combustion, and exhaust ), we can classify piston engines into two further 2 subtypes;

• 2-Stroke ICE Engine

• 4-Stroke ICE Engine

Subtype no 1 ) 2-Stroke ICE Engine

In this engine, intake, compression, combustion, and exhaust are done in 2 strokes. For example, 

• 1st stroke: When the piston moves down ( due to combustion stroke ), the inlet pipe is exposed, letting intake of fuel & air inside the cylinder and pushing the residual fuel out from the exhaust pipe. Hence, power, intake, and exhaust stroke occur in 1st stroke. 

• 2nd stroke: Then the piston moves up ( 2nd stroke ), it compresses the fuel, and when the piston is at Top Dead Center ( TDC ) spark ignites the fuel, creating a combustion ( here 2nd stroke ended ). Then it pushes the piston down ( again 1st stroke repeat ), which rotates the crankshaft.

Subtype no 2 ) 4-Stroke ICE Engine

As the name suggests, in this engine, the intake, compression, combustion, and exhaust happen in 4-strokes;

• 1st stroke: After the exhaust step, when the piston moves down from Top Dead Center ( TDC ) to Bottom Dead Center ( BDC ), it creates a vacuum. At the same time, the inlet valves open up, letting a mixture of fuel & air into the vacuumed chamber. This step is also called the intake stroke.

• 2nd stroke: Now, the piston moves from bottom to top, and the fuel inside is compressed, which increases its pressure & temperature needed for combustion. This stroke is also called a compression stroke. 

• 3rd stroke: Now, when the piston is at the Top position, the spark plugs light up, causing a combustion and huge pressures which push the piston at full speed downward, and which in return rotate the crankshaft. This stroke is also known as combustion/power stroke. 

• 4th stroke: In this stroke, the piston moves from the bottom to the top and pushes the residual fuel outside through the exhaust/outlet valve. This stroke is also called as exhaust stroke.

That’s it. The whole cycle repeats itself again and again. 

Type 3: Brayton/Turbine Engines

A Turbine Engines work on the Brayton cycle, which also consists of 4 stages, as the Otto Thermodynamic cycle. Here is an easy explanation of Brayton’s cycle & how a normal turbine engines work;

Step 1) Isentropic Compression: In this step, the incoming air passes through a compressor, which squeezes it to produce high-pressure & high-temperature air.

Step 2) Constant-Pressure Heat Addition: In this step, the compressed air enters a heat chamber, in which either burning fuel ( jet engine ) or nuclear heat further increases the temperature of the compressed air, but a constant pressure is maintained.

Step 3) Isentropic Expansion: In this step, the hot and high-pressure air is allowed to pass through a turbine, which gives it an area to expand, and hence it pushes the blades with strong force and creates a rotation, which then produces mechanical energy. 

Step 4) Constant-Pressure Heat Rejection: Now, in a jet engine, after passing through the turbine, the air is then allowed to either leave the system through the nozzle, which is placed at the end. However, in a closed-loop system ( nuclear plants, spaceships, and marine engines ), the air is again diverted through pipes back to the inlet of the compressor. 

 

Uses of the Internal Combustion Engine

There are many uses of the Internal combustion engine in almost all areas of life, as you can see in the examples below;

Most automobiles, like cars, motorcycles, and trucks, commonly use 4-stroke gasoline or diesel engines, although smaller motorcycles may use 2-stroke engines.  

Civil aircraft, like light aircraft and helicopters with piston engines, make use of 4-stroke gasoline (avgas) engines. However, ultralight aircraft sometimes use 2-stroke engines due to their low weight.  

Marine transport, which includes boats and ships, and other recreational watercraft like jet skis, employs a mix of gas-powered engines. Larger vessels commonly use diesel engines, while 2-stroke or 4-stroke gasoline engines are common in smaller vessels.  

Portable and backup power generators can employ 4-stroke gasoline or diesel engines. Smaller units may feature 2-stroke engines, but all units, no matter the size, utilize 4-stroke gasoline or diesel engines.  

Construction equipment, most in demand—bulldozers, excavators, and cranes—are built around 4-stroke diesel engines, which provide the heavy-duty torque and durability required for their work.  

Agricultural sector: Diesel 4-stroke engines are the overwhelmingly favored option for agricultural machinery like tractors, harvesters, and sprayers because their ability to fuel the machine for hours on end is more versatile than other options available.  

Industrial machines, compressors, and pumps, and small engines are most often fueled by 4-stroke gasoline or diesel engines, with limited smaller equipment utilizing 2-stroke engines instead.

Recreational vehicles such as ATVs and snowmobiles can use either 2-stroke or 4-stroke gasoline engines, depending on the desired weight and power ratio. 

Emergency Vehicles: Fire engines, ambulances, and rescue boats all fall under emergency service vehicles, and they are mostly powered by 4-stroke diesel engines due to their good performance and reliability. 

Military Applications: 4-stroke diesel engines are often used to power military uses like armored and mobile units. However, 2-stroke and turbine engines are mounted on small UAVs and drones for their compact design and fuel-efficient power delivery.

DIY builds of the Internal Combustion Engine

There are many sellers out there who sell DIY engine kits, some of which even work. But out of all sellers, I like the most are EngineDIY ones, as they sell all kinds of working DIY models, and their prices are very low. 

So, if you work in a school teaching STEM education or are just an enthusiast looking to learn the working of ICE in a fun way, you can buy this v8 engine model kit from them. One great thing about this ICE V8 engine kit is that its piston, crankshaft, and even inlet & outlet valves move due to the help of the timing belt. Plus, it has a light & sparkler to create a realistic feeling. 

Here is a step-by-step guide to assembling the kit in an easy way;

Step 1) Prepare parts: First of all, get all the parts out and place them on the table as shown in the picture. 

Step 2) Start with Crank Shaft: Now, pick the button housing and place the crank shaft in the. Then pick all the pistons and attach them to the crankshaft. 

Step 3) Close the casing: Now attach the inlet & outlet valves and close the housing completely. 

Step 4) Attach the Timing belt: Pick all the gears, attach them to the housing, and then adjust the timing belt on them. Now close the cover of the timing belt. 

Step 5) Finalize & Run the Engine: Attach the fan and power wires to the engine. Finally close all the screws and enjoy the working of the engine with just one click. 

Wrap up: 

In short, the Internal combustion engine has lifted us up from 10 km/hr slow-moving carts literally to the skies with jet engines ( that have a speed of thousands of km per hour ). These ICE engines have completely changed our ways of transportation, our agricultural practices, and even our ways of war. 

It is a tragedy that Étienne Lenoir's work on engines was not appreciated at his time, even though he had made the world’s first car in 1863, named Hippomobile. Unfortunately, in the later days of his life, he died poor. So, we dedicate this article to him who completely changed the world. 

Last but not least, if you want to buy STEM DIY engine models of all kinds like stirling engine kit , steam engine kit , diesel, ICE, or even jet ones, you can buy from us at EngineDIY. 

FAQs

1. When was the world’s first car made?

Well, in the history books, the world’s first ever car was made by Karl Benz in 1885, and he named it a motorwagen. 

But I don’t think it was the world’s first car because Eteiner Leiner ( he made the world's first engine ) in 1863, built a Hippomobile and drove it 11 km from Paris to Joinville-le-Pont. So, in the true sense, it was the world’s first car. 

But it was rudimentary with no clutch system, and it was not commercially made, which is why historians don’t consider it the world’s first car, which is unfair, as he laid the foundation, which gave the idea to Karl Benz to make his car. 

2. The world's first driver?

Well, if you ask me, I would say Eteiner Leiner was the world’s first driver who rode 11 km from Paris to Joinville-le-Pont. But as his Hippomobile isn’t considered the world’s first car so he wasn’t considered the world’s first driver. 

So, in 1888, Bertha Benz drove his husband Karl Benz’s Motorwagen from Mannheim to Pforzheim, which is approximately 106 km. She travelled that distance with her sons and she didn’t even tell his husband.