INSIDE THE HEART OF MACHINES: HOW INTERNAL COMBUSTION ENGINES ACTUALLY WORK

 

It started with a broken blender.

Okay, right. That's not exactly how scrappy it was.

However, after lots of reading about pulleys, wedges, levers and the likes. I started to see how some of these simple machines were weaved together to created some machines.

A simple example, is a nail cutter. It is a simple lever. A load, fulcrum and pivot. In everyday life.

I didn’t grow up with a toolbox in hand or a workshop down the street, but I did have a growing itch to figure out how machines work. One part curiosity, one part stubbornness, I started taking apart devices just to see what was inside.

Soon, all the simple understandings led me to I found uncovering something bigger and way more powerful, none other than the internal combustion engine. You know, the thing that makes cars go vroom! but also powers lawnmowers, generators, and even jet skis.

It's current state in terms of its future use, hangs, in the balance, as things are moving electric. However, nonetheless, it is important to touch on it, to understand it as we march into a possible electric engine future. Also, this was the first complex machine I figured out.

In this post, I’ll walk you through what I’ve learned so far about how internal combustion engines (ICEs) work. I’ll keep it clear, simple, and maybe even a bit fun, because honestly, these machines are kind of amazing.

🧠 So, What is an Internal Combustion Engine?

A simple layout of the working parts of an internal combustion engine

Image source: https://sites.aub.edu.lb/productdesignprogram/internal-combustion-engines/

At its core, an internal combustion engine is a machine that turns mini-explosions into motion. Controlled explosions, of course.

From the picture above, the pistons are pushed down in alternate fashion, through the mini-explosions from an air-fuel mixture, introduced, through the camshaft, which is ignite by spark plugs which produce a light electric spark. The alternate fashion of the explosions, involve, one going down after a mini-explosion, another goes up for a mini-explosion. Imagine this, as how legs pedal on a bicycle. This movement provides force to the crankshaft, which rotates gears, in the gear box or transmission. Below is a video that shows how it works.

The name "internal combustion" comes from the fact that it burns fuel inside itself, and the force from that burning fuel is what moves things, moves pistons, which in turn move force to things like wheels, blades, or propellers.

You pour in fuel, mix it with air, light it up, and boom! Motion. That’s the basic idea.

⚙️ The Four-Stroke Dance

Now let us look at how everything works closely with those mini-explosions creating force that is transferred to other parts of a machine

Most engines we see in cars, motorbikes, and small machines use something called a four-stroke cycle. This is the rhythm that makes the engine run smoothly. Let’s break it down:

1. Intake

The engine opens a valve, and a mixture of air and fuel gets sucked into a chamber (the cylinder). Think of it like the engine taking a deep breath.

2. Compression

A piston (like a metal plunger) moves up, squishing that air-fuel mix tightly. This step builds pressure, kind of like shaking a soda can.

3. Combustion (Power)

Here’s the fun part, a tiny spark (from a spark plug) ignites the compressed mix. BOOM. That explosion pushes the piston down hard. This is where power is made.

4. Exhaust

The engine opens another valve and pushes out the leftover gases, like the engine exhaling. Then the cycle starts over again.

This happens really fast! Hundreds to thousands of times per minute in each cylinder. It's like a little orchestra of fire and metal, playing in perfect timing.

🔁 From Up-and-Down to Round-and-Round

So we’ve got pistons moving up and down thanks to these mini-explosions. But how does that power get to your wheels or propellers?

That’s where the crankshaft comes in. Like it was mentioned, imagine pedaling a bike, your legs go up and down, but the wheels turn in a circle. The crankshaft does the same thing, it turns the piston's up-and-down motion into spinning motion that machines can use.

🧱 Engine Shapes and Layouts

Not all engines are built the same. Depending on what they’re powering, engineers use different shapes or “layouts” of the engine cylinders:

• Inline Engines – All the cylinders are lined up in a row (like most 4-cylinder cars).
• V Engines – Cylinders are arranged in a “V” shape. Compact and powerful. Common in bigger cars and motorcycles.
• Flat or Boxer Engines – The cylinders lie flat and oppose each other, like two boxers punching. Found in some sports cars and motorcycles.

Each design has pros and cons, some save space, others reduce vibration or deliver more power. It’s all about what the machine needs to do.

🚜 More Than Just Cars: Where Else Are ICEs Used?

When we think of engines, we usually think of cars or motorbikes. But internal combustion engines show up in way more places than you’d expect. Here are a few machines that run on them:

• Lawnmowers – Small, single-cylinder engines that are easy to start and light to carry.
• Generators – These use ICEs to spin turbines and generate electricity when the grid is down.
• Jet Skis – Compact but powerful engines designed for quick bursts of speed on water.
• Go-Karts – Small but fun engines with a lot of personality.
• Water Pumps and Pressure Washers – Often powered by gasoline engines, especially in outdoor or remote settings.

The versatility of ICEs is part of why they’ve stuck around so long. They’re reliable, pack a lot of power in a small space, and don’t need a power socket. However, like mentioned, it's future is in the balance, given the new shift to be eco-friendly by many nations.

🧩 What I Learned (and Why It’s Cool)

What blew my mind (pun intended) was how precise everything inside an engine has to be. It looks like huge chunk of metal but the processes and details are very intricate to build, more so, for more specific functions and devices. The timing of the spark, the air-fuel mixture, the way valves open and close, all of it has to be perfectly synced.

But once I understood the basics, it all started to make sense. Suddenly, I could see what was happening when I heard a motor start. I knew what was going on when a lawnmower sputtered or why a generator might struggle to run.

It’s like learning to read a new language, but instead of letters, it’s gears, pistons, and explosions.

🏁 Final Thoughts: Machines Aren’t Just Metal

Studying internal combustion engines made me realize something, machines aren’t just cold metal parts. They’re full of design, rhythm, and problem-solving. They’re built by humans to solve real problems, and once you start taking them apart, you appreciate the thought behind every nut and bolt.

Whether you're a fellow curious mind or just someone who likes to understand how things work, I hope this helped bring the engine to life a bit.

Next up? Maybe I’ll take on turbochargers, or even peek inside an electric motor. But for now, this engine journey has been one explosive ride.

💬 Over to You

Ever taken something apart just to see what’s inside? Have a machine you’ve always wanted to understand? Drop your thoughts in the comments or tell me what engine you think I should explore next.