How Car Engines Work


Have you ever looked at your car engine and saw a mess of parts all seemingly jumbled together? What in the world does all that stuff do, and how much will it cost to fix? Don’t be intimidated; the internal combusion engine is an engineering marvel, and the basis for our entire civilization; without them our society literally could not function. This is how they work, in the simplest of terms.

The internal combustion engine is used in just about everything that moves: cars, trucks, lawn mowers, planes, boats and ships, you name it. Basically this engine creates a series of controlled explosions. Lots of them. These tiny explosions cause parts in the engine to move, with that energy transferred to your car wheels (or a propeller, in the case of a boat orf a plane).

engine diagramGasoline is mixed with air in the cylinders of an engine, called the combustion chamber. It’s a place where the explosion happens.

The air and gas are squeezed together by a piston, and then ignited by a spark plug, creating the explosion. The explosion forces the piston down, and the piston transfers that energy to the wheels.

Presto! You have motion. Now, the combustion chamber has to be sealed at the exact moment the explosion takes place. So, there are valves that seal it, just like there are valves in your heart, or your plumbing in your home. One set of valves lets air and gas in, another set of valves lets the exhaust from the explosion escape.

This is what the sequence looks like in motion, when you are driving your car:

220px-4StrokeEngine_Ortho_3D_Small1. Intake valve opens, air and gas go into the combustion chamber

2. Valves close, the piston moves up, squeezing the air and gas together

3. The spark plug at the top ignites the mixture. Poof! Explosion! The piston is forced downward.

4. Exhaust valve opens, exhaust leaves combustion chamber

This sequence happens very fast. In fact, you know the term RPMs? When you look at a tachometer in your car, you see RPMs in the thousands; 1,500 RPMs, for example. It stands for Revolutions-Per-Minute. Well the above cycle is just one revolution. Think about that for a moment. The above cycle happens thousands of times per minute!

What’s really cool about this is that everything has to happen in a very specific sequence, at a very specific time, very very quickly. Take a look at the above animation. See those knobby things at the top, on the left and right? The ones that rotate and push the valves down? Those things are called camshafts. The knobby shape is designed to open the valves at exactly the right moment. This is what a camshaft looks like:


OK, now that you have the basic concept, here’s a more detailed look at this cycle of what happens in your car engine. This animation shows an enginge with a fuel injector. Injecting fuel directly into the combustion chamber makes an engine run more effeciently, which is why most cars have them now. [image source:]


Here’s a short animation of the pistons moving up and down. There’s a lot of force in those tiny explosions, which push the pistons back down. That force has to go somewhere, and that’s why the pistons are connected to a shaft that transfers the energy to the wheels, making them turn.


This is a great animation of a V8 engine at work, showing all the various parts. There is obviously a lot more to engines than this; the point here was to give you the most basic concept on how they work. There are some cool links at the bottom of this post that will give you a lot more information about how your car engine works. Don’t be intimidated; these are miraculous machines, and the more you know about them, the more informed you’ll be when they need to be serviced.

Finally, this is a fascinating video of a man who builds intricate tiny enegines for all sorts of vehicles; boats, cars and planes. These tiny engines are a work of art in their own right, made by a man who loves the mechanical art of the internal combustion engine.







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