The invention of theinternal combustion engine in the 19^th century has revolutionized transportation over land, water, and air. Despite their omnipresence in modern day, the operation of an engine may be cryptic. Over the course of this article I’d like to explain the functionality of all the basic engine parts shown in the demonstration below. You can drag it around to see it from other angles:

It’s hard to talk about a mechanical device without visualizing its motion, so many demonstrations in this blog post are animated. By default all animations areenabled, but if you find them distracting, or if you want to save power, you canglobally pause them.disabled, but if you’d prefer to have things moving as you read you canglobally unpause them.

An engine like this may seem complicated, but we will build it up from first principles. In fact, we’ll start with a significantly simpler way of generating a rotational motion.

Crank

Let’s look at a simple crank. It consists of ahandle, acrank arm, and ashaft. When aforce is applied to the handle the shaft rotates which we can observe by looking at the attached disk:

Theforce applied at a distance from theshaft generatestorque. The harder we push on thehandle, the bigger the torque on theshaft. This cranking mechanism is precisely what converts linear force into torque in a manual coffee grinder or a bicycle.

It’s one thing to power something using our own muscles, but the entire point of building an engine is to avoid manual labor and have the device exert the effort instead. To do that we need to find a reliable source of a strong force that is easy to direct. Thankfully, such device was invented hundreds of years ago – acannon does exactly what we need. In the demonstration below you can observe how acannon ball is fired from acannon. The diagonal lines indicate across section view – it lets us see what’s going on inside an otherwise obscured region:

As the gun powder is set on fire it quickly produces a huge amount of gases, which push the cannon ball down the barrel. Since the ball snugly fits inside it can only go in one direction. While reliable and easy to direct, a cannon ball won’t be very effective at pushing the crank:

We’ve only been able to do a partial turn of theshaft and the cannon ball is long gone. However, with a few modifications we can harness the pushing power of the explosion in a significantly better way.

Firstly, we’ll replace a cannonball with apiston that has a cylindrical shape and a hole drilled in it. We’ll then use apin to attach to it arod that can swing freely on acrankshaft:

As the name implies, thecrankshaft consists of both the rotating shaft and the crank on which a force is applied. By putting this assembly inside a simplified cannon shell, acylinder, we’ve managed to solve the problem of the escaping cannon ball, as thepiston is limited in its downward movement and will return up as thecrankshaft keeps turning:

Notice that thepiston has now a minimum and a maximum position it can reach within thecylinder. A single movement over that length in either up or down direction is called astroke. If we now trigger the explosion, the combustion gases will push thepiston down, which turns thecrankshaft:

It’s still not a very exciting machine as it only does useful turning work once. To make it more practical we need to keep repeating the cycle of explosions – we have to add in new fuel, trigger a combustion process, and remove the exhaust gases, over and over again.

Solid fuels like black powder are not very practical for an automated machine. It’s much easier to deal with fuels in fluid forms – their intake can be controlled by various valves. We’ll modify the cylinder we’ve built so far by adding new openings at the top of the combustion chamber:

It may be hard to see how the various openings are laid out, so let’s take a look at the cross section view:

Through the first large curved opening we’ll provide a mixture of gasoline and air and through the second one we’ll remove the exhaust gases. Those two openings will be guarded by theintake valve and theexhaust valve. Finally, to light the mixture, we’ll use an electric spark generated by an exposed ends of awire. Let’s see how all the pieces fit together:

We’re now ready to use this machine to do useful work. At first we’ll open theintake valve while thepiston is moving down letting the air with fuel come in which I’ve symbolized using the yellow color. This is theintake stroke:

Once thepiston reaches its lowest position theintake valve closes, and thepiston starts to move back which compresses the mixture of air and fuel which increases thethermal efficiency of the combustion. This is thecompression stroke:

Voltage runs through the open ends of the wire, generating a spark which ignites the air-fuel mixture. The expanding gases created by the combustion push thepiston down, creating torque on thecrankshaft. This is thepower stroke:

Note that the flame propagation inside a cylinder isquite complex, and what you see here is a simplified visualization. Thecylinder is now filled with the exhaust gases which we can vent out through another hole by opening theexhaust valve. This is theexhaust stroke:

We’re now back to where we started and the cycle is complete. Let’s look at those four steps together:

Since thepiston moves down twice and up twice, it does a total offour strokes and the engine we’ve built is known as afour-stroke engine. Notice that it takestwo revolutions of thecrankshaft for thepiston to doone full cycle of the work as it goes through the four phases: intake, compression, power, and exhaust.

While functional, the engine we’ve built is more of a toy example that doesn’t show a lot of the engineering ingenuity behind many components of real internal combustion engines. Let’s build on the principles we’ve devised so far by constructing a more realistic machine – an engine that one could find in a car.

Engine Block

Let’s start with the biggest and heaviest part of an engine – theengine block. It forms the main body and mounting structure for other parts:

Notice that this block containsfour largecylindrical openings that define the four cylinders. Recall that a piston exerts a pushing force on the crankshaft only during the power stroke, so only for about a quarter of time. This uneven action creates a lot of vibration. While it’s often acceptable for smaller engines e.g. in a lawn mower, a typical car engine has more than one cylinder to ensure a more even delivery of power. I’ll discuss these concepts in more depth near the end of the article.

Since the four cylinders are inline, the engine we’ll build is known as an inline four cylinder engine. Other engines may use different arrangements of cylinders, usually in aflat orV-shape configuration.

The sides of the block are reinforced by various ribs to improve the rigidity of the structure – the body has to withhold the power of the explosions inside the cylinders. You may also have realized that the top part of the block is perfectly flat – we’ll soon attach another component there. If you look at the cross section of the block you’ll notice that the areas around cylinders are empty:

Those passages are there for the coolant to flow around the cylinders and take the heat of the combustion away. While I’m not going to dive into details of engine cooling, it’s worth noting that engines should run at a specific operating temperature and the coolant pump, thermostats, and radiators make sure that the engine isn’t running too cold or too hot.

Crankshaft

Let’s look at the first big part we’ll mount onto the engine – the crankshaft:

Notice that the crankshaft has five main cylindrical parts that define its axis of rotation, they’re called themain journals. There are also fourrod journals that are positioned off-axis. All the journals are connected viawebs. Note that while the sections have different colors here, the entire crankshaft is made from a single piece of metal.

You may wonder why the two innerrod journals are offset differently than the two outer ones, so let’s pop thepiston assemblies on and see how they’ll move on the crankshaft:

Since therod journals are at different locations each of the four pistons can run at a different phase of the four stroke cycle. Notice that the distance between the center of themain journals and therod journals defines how far up and down the piston goes in the cylinder.

A real piston and its connecting rod have some mass so they end up creating a weight imbalance on a rotating crankshaft. To counteract that mass, thewebs have elongated shape to form a counterweight that helps to even out the inertial forces on the shaft.

One could assume the installation of the crankshaft in theengine block is as simple as putting it directly in a designated spot at the bottom:

Unfortunately, that wouldn’t really work. During engine operation the pistons exert a lot of force on the crankshaft and themain journals would just rub against the housing creating a lot of friction that would wear the parts down. To fix that we need to firstly put in somebearings that will help to make the rotation of the crankshaft smooth:

These strips of metal don’t look like much, butbearings are usually made from a softer material which causes them to wear first which prevents degradation of the crankshaft itself in case any contact occurs. Most of the time, however, the crankshaft doesn’t actually touch thebearings at all. Notice the small hole in thebearing that matches the corresponding hole inside theengine block:

Through that hole the engine pumps oil under pressure. The crankshaft’s diameter is slightly smaller than thebearings' inner diameter so oil fills the tiny gap between the two surfaces. Presence of oil is critical here as it creates conditions forhydrodynamiclubrication. Oil sticks to thebearings and thecrankshaft, but since thecrankshaft rotates it creates a variation in velocity ofoil between the two surfaces. In the demonstration below the small arrows symbolize the local velocity of the liquid:

The difference of diameters causes a wedge-like shape to develop which then creates an area of increased pressure that lifts thecrankshaft journal away from thebearings. Note that the size of the gap in the demonstration is not to scale, but in real running engines the rotatingcrankshaft should float completely on a very thin surface of oil.

You may have noticed that one half of the bearings also contains a small gutter which creates a small pool of oil under pressure. Moreover, the crankshaft has small holes in it:

Those passages are actually connected inside and the oil from the pool in the bearing travels through the little passages in the crankshaft itself. This brilliant solution distributes the oil from themain journals to therod journals, which are constantly changing their position inside the engine. The demonstration below shows one of the many typical arrangements of these passages and the presence ofoil in and on the crankshaft:

Let’s finally put thecrankshaft in. We’ll clamp it down using fiveend caps that have their correspondingbearings put in and we’llscrew everything together:

Thosescrews have to be tightened to a precise torque – it has to be high enough so thatend caps are able to keep thecrankshaft in place despite the force of explosions pushing down on it through the piston rods, but the torque on thescrews can’t be too high to avoid any deformation of the circular shape of the final opening in which the crankshaft lies.

Pistons

The crankshaft itself is there to receive the force from the pistons, so let’s look at at one up close:

Firstly, notice all the empty spaces inside thepiston. They’re there to reduce the weight – apiston should be as light as possible to minimize the inertial forces created by its reciprocating motion. In this piston the top part known as thepiston crown has a dish-like cavity in it. Other pistons may be flat or havemore complicated shapes.

Pistons have actually slightly smaller diameter than the cylinders, otherwise they couldseize during movement resulting in a catastrophic engine failure. However, the piston still needs to seal the combustion chamber and prevent gases from leaking around the piston. This problem is solved bypiston rings that are placed in the grooves on top of thepiston:

On their ownpiston rings have a fairly big gap, but when placed in the cylinder they’re squeezed into a fitting shape. Note that the fitted ring still has a tiny gap:

While the gap shrinks when aring gets warmer and expands, the gap should never completely close as the ring may break under pressure. The clearances in the sizing of the rings are very precise. Since thering is squeezed into a smaller shape, it wants to expand and that tension helps it form a tight seal with the walls of the cylinder. That tension is also reinforced by the pressurized gases getting into the piston grooves and pushing the rings further against the cylinder walls.

The pistons in our engine have three rings with the top two primarily helping to keep the pressure inside the combustion chamber. The third one serves a different role – it’s anoil control ring. The walls of a cylinder under a piston are constantly sprayed with a supply of oil to ensure a smooth movement during strokes. On a downstroke the oil ring scrapes the excessive amount of oil which escapes through the openings in the ring and the groove of the piston:

Top of a piston faces the enormous heat of combustion. The rings are in contact with the pistonand the cylinder walls so they heavily participate in heat dissipation. Moreover, since the top part of the piston is in closer contact with the hot gases, it reaches a higher temperature than the lower parts and therefore it expands more. To account for that the pistons are tapered on top so that when the different areas of a piston reach their operating temperatures the shape is more even.

The area of the piston below the rings is called askirt. Parts of the skirt are, through a thin layer of oil, in contact with cylinder walls during stroke which stabilizes the piston. While they look perfectly round, piston skirts are actuallyslightly oval.

Apiston is attached to itsrod via agudgeon pin. Perhaps you’ve noticed that apiston has tiny grooves near the end of the pin opening. We’ll putsnap rings inside them – they’ll prevent thepin from leaving the hole:

Pistonrods themselves are very strong as they have to withstand the force of the explosions pressing on the piston during combustion, while also resisting a stretching and pushing forces due to the inertia of the piston changing its direction of movement.

Thepistons with the connectingrods andbearings can be slid down the cylinders and attached to thecrankshaft:

Recall that therod bearings are lubricated by the oil coming in through crankshaft passages. Let’s see how the entire thing rotates:

The movement of apiston as the function of thecrankshaft angle deserves a closer look. In the demonstration below I marked the maximum, minimum, and a midpoint traveled distance of apiston during its stroke. You can control the rotation of thecrankshaft with a slider:

Notice that when the crank arm has done a90° turn, i.e. halfway through between top to bottom angle, thepiston has moved up byless than half of its total stroke distance. It’s a simple geometrical consequence of the length of arms of the triangle formed by the crank arm, the connecting rod, and the vertical baseline.

The maximum piston’s position is known as itstop dead center, and its lowest position is known asbottom dead center. As the cylinders move up and down between those two extremes they sweepcylindrical volumes:

The area of a cylinder’s circular cross sectionA times the stroke length of a pistonS define the displacement volume of that cylinder, and the displacementV of the entire engine is the sum of displacements ofall of itsn cylinders:

If a single cylinder’s displacement is half a liter, then a four cylinder engine would be known as a 2.0-L engine. In the most basic setup, the bigger the engine displacement, the more air the engine can suck in, and the higher its peak power.

Closing the Lid

With the parts we’ve assembled so far we’re getting close to completing the combustion chamber. We’ve created the walls with the engine block and the movable bottom with the pistons. We just need to seal it from the top – this is where thecylinder head comes in:

There are a lot of openings there. Firstly, notice four large sections at the bottom – these dome-like cavities will form the top of the combustion chamber. Each of those four sections is the same, so let’s look at the individual segment up close:

In this engine each cylinder has four major openings – through two of them the intake air is sucked in and through the other two the exhaust gases are let out. If youlook at the head from a side you’ll notice that each pair of the openings is joined into one elliptical hole that exits on the side of the head. Those passages are known as intake and exhaust ports. Additionally, there is asmaller hole drilled centrally through the axis of each opening – they’re there for theintake andexhaust valves:

Modern engines typically use more than oneintake andexhaust valves per cylinder as it increases the flow of gases in and out of the combustion chamber. Moreover, theintake valves are usually a little bigger:

When the piston moves down on an intake stroke, the pressure difference it creates is no larger than that of the incoming air, which, for traditional engines, is roughly equal to the atmospheric pressure. However, at the end of the combustion stroke the pressure inside the cylinder is many times higher than the atmospheric pressure, so it’s significantly easier to expel the combustion gases than to suck the intake air in. For this reason the intake openings and valves are larger.

Let’s look at the operation of those valves up close. Firstly, the seal they form has to be very tight so that the only pathway for the expanding gases created in the combustion is to push the piston down. The edges of avalve and its seat have a conical section so that the seal becomes tighter as the valve is pressed up:

In our toy engine the valves magically opened and closed on their own, so let’s see how it can be actually done in practice. To keep a valve shut we’re going to use aspring to keep tension on a closedvalve. We can then lock thespring against the valve using simple locking mechanism that consists of twovalve keepers, aspring retainer, and aninverted bucket:

Notice that the top part of a valve has a little groove in it so that thekeepers can lock in place. Thekeepers themselves form a section of a cone that theretainer wedges against:

Since thekeepers are locked in the grooves, theretainer can’t move which holds thespring under tension. Thebucket provides a big and smooth surface for a force to transfer onto a valve – now whenever we push on thebucket thespring will push it back in place:

We’ve got the return mechanism all figured out, but this still leaves the problem of actually pressing the valves – they need to be opened at a certain cadence which depends on the movement of the piston inside the cylinder. That periodic nature of the operation implies that we should use some sort of rotary motion to push the valves.

We can shape a piece of metal so that it pushes on the valve at different offsets as it rotates on ashaft – it’s known as acam. Thespring ensures that thebucket is tightly pressed against thecam and follows its shape:

The shape of the cam defines when, for how long, and how much the valve is opened. In the demonstration below you can control theheight andangular span of the section of the cam profile thatdeviates from a circle and see how it affects the position of thebucket and thus valvelift at differentangles. The plot in the upper part shows the offset of thebucket relative to its normal position as the function of camrotation angle:

The shape of the cam is critical for defining the way the engine operates. All cams for a set of intake or exhaust valves are usually placed on a singlecamshaft:

Most modern engines use twocamshafts, one forintake valves and another forexhaust valves. Let’s see how thecamshafts open and close valves during a typical engine operation:

All cylinders go through four stages in a predefined order. The timing of the valves is actually not as straightforward as it was in our toy engine so let’s look at it up close:

Firstly, notice that theintake valves closeafter the piston reaches the bottom end of theintake stroke – the air coming through the valve has some inertia, which, especially at high engine speeds, makes it pile up in the cylinder despite the opposite movement of thepiston.

Similarly, theexhaust valves open before thepiston reaches the bottom of thepower stroke, as the majority of the useful work has already been done by the gases and the pressure surplus in the cylinder should be minimized so that theexhaust stroke doesn’t have to actively compress the exhaust gases.

Theintake valves openslightly before thepiston reaches the top end of theexhaust stroke. When combustion gases escape through theexhaust valves they help to create a “scavenging” effect that helps to pull the intake air in. For that reason theexhaust valves close after thepiston reaches the top of theexhaust stroke.

An engine running at low speed may have a different ideal parameters than an engine running at full speed, so many modern engines usea few methods to vary both the timing and lift of the valves during operation.

We can now assemble the pieces together. While the top surface of the engine block and the bottom surface of the cylinder head are very flat and smooth, they need to form a perfect seal as they have to prevent the combustion gases from leaking through. Agasket, often made from a softer, compressible metal, is placed in-between the two and the head isbolted to the block:

Thebolts are tightened to the predetermined torque in multiple steps and in a specific order to ensure that the head doesn’t deform during assembly. The sturdiness of the headbolts is critical as they literally have to contain the force of the explosions inside the cylinder.

Thecamshafts are then installed – they’re held in place by theircaps andbolts:

The only remaining piece of the puzzle is to how to turn thecamshafts while ensuring they’re synchronized to the movement of the pistons. To achieve this, most engines use a rubbertiming belt that is driven by agear mounted to the crankshaft itself. Thetiming belt is teethed so that it locks in the notches on thetiming gears, therollers keep thebelt in tension:

Recall that in a four stroke engine a single cycle of operation requires two full revolutions of the crankshaft as the piston goes throughintake,compression,power, andexhaust phases. However, the intake and exhaust valves open just once during that cycle so thecamshafts should do just asingle revolution during that time.

To fulfill this requirement thecrankshaft gear is twice as small as thecamshaft gears – this ensures that thecamshafts rotate just once when the crankshaft rotates twice which you can verify by observing a smallblack dots at the perimeter of the gears:

Combustion

In the examples so far we’ve assumed that the intake valve let in a mixture of air and fuel, and that indeed was the case in older engines that used acarburetor to create the mix.

Modern engines, however, use a fuel injection system where the amount and timing of fuel injection is controlled by an electronicEngine Control Unit, often abbreviated as ECU. At appropriate time the solenoid inside the injector isenergized which electromagnetically pulls theneedle up, which in turns lets the pressurized fuel escape through the tiny outlet holes. When the power to the solenoid iscut, thespring pushes the needle back to seal the nozzle:

In some engines the injection happens in the intake port, very close to the intake valve itself, but in our engine we’ll use a direct injection system in which the fuel is put directly into the cylinder itself.

The fuel and air mixture in the combustion chamber is lit by aspark plug. In a simplified form a spark plug consists of two pieces of metal separated by aceramic insulator. Theouter shell is connected to the engine body which acts as a ground, and thecentral electrode is connected to a source of voltage high enough to bridge the gap to the tip of theouter shell which creates a spark:

That high voltage is generated by an ignition coil. In older engines there was a single coil that sequentially provided high voltage to individual spark plugs, but in modern engines each spark plug will usually have its own coil with the discharge controlled by the ECU.

With a set ofinjectors andspark plugs in hand we can finally fill the remaining holes in the engine head. I’ll hide the rest of the engine so that we get a better view as to where they fit:

Let’s see how aninjector and aspark plug work together during the strokes. Note that normally theinjector is attached to a fuel rail feeding it highly pressurized gasoline and aspark plug is connected to its coil, but for the sake of clarity they’re not being shown here. The air is depicted as a blue gas that turns yellow when mixed with fuel:

You may notice that thespark plug fires before the piston reaches the end of the compression phase – it’s done on purpose since it takes a moment for the burning of the air-fuel mixture to begin. Let’s take a look at all four cylinders firing in sequence:

All the demonstrations in this article run at very slow speeds, but it’s worth mentioning how fast things happen in an actual car. For an engine running at a modest speed of 1500 revolutions per minute there are 25 revolutions of the crankshaft everysecond. Each cylinder fires once per two revolutions of the crankshaft, but since we have four cylinders, there are actually around 50 explosions per second happening in an engine running at that speed.

Theratio of air to fuel in the combustion chamber is important as simply adding more fuel doesn’t necessarily make the cylinder pressure bigger as we’ll just end up with incompletely burnt gasoline. To actually increase the speed of the engine we need to increase the supply of fueland air.

Let’s look at the pressure inside the cylinder a bit closer. During the intake stroke the piston creates a negative pressure difference which sucks the air in. During the compression stroke the pressure increases due to shrinking volume, only to increase even more due to combustion. It’s finally reduced by the expanding volume of the chamber as the piston goes down during the power stroke:

The pushing force generated on the piston is proportional to the pressure in the cylinder, however, thetorque generated by that force is also affected by other factors. Firstly, observe that during the compression stroke, the pressure inside the chamber pushes on thepiston and through therodagainst the rotation of thecrankshaft:

Secondly, the magnitude of torque depends on the effective length of the arm of force, but that length changes during crankshaft rotation. For instance, when thepiston is at the top dead center the gases merely push thecrankshaft down, but they don’tturn it because the force arm has the length of zero. In the demonstration below thered dashed line shows the direction of therod force and theblack line show the arm of force on the crank:

If we account for these effects we can calculate that the torque generated by the pressure inside one cylinder is roughly as follows:

However, these are not all the forces that affect the crankshaft. Both piston and its connecting rod have some mass and during crankshaft’s rotation they keep changing their direction of motion. Let’s look at the plot of the velocity of a piston as it moves up and down the cylinder when the crankshaft rotates with a constant angular velocity:

You may be surprised that the plot isn’t symmetrical, but it’s just a consequence of the already discussed behavior of the crank mechanism taking more time to move through the lower half of the stroke compared to the upper half of the stroke.

Let’s consider a piston in a top dead center position – as the piston reaches that point its velocity is 0, so the crankshaft has to drag the piston down. Roughly halfway through its stroke the piston reaches its maximum velocity, and now the crankshaft has to actually slow the piston down so that it stops moving by the time it reaches the bottom dead center position. The piston, however, wants to keep going, so it exerts a pushing force. These inertial forces keep oscillating back and forth creating an inertial torque on the crankshaft:

The magnitude of the inertial forces depends on the speed of the piston and thus on the crankshaft’s rotational velocity. That system is very dynamic since crankshaft’s rotational velocity in turn is affected by the inertial forces acting on it.

The resulting output crankshaft’s torque is a sum of these pressure-based and inertia-based torques. The cumulative diagram of torque on the crankshaft from a single piston looks roughly like this:

As you can see, the torque created by a single piston is very varied. Even when we overlap the resulting torque from all four pistons the total torque is still fairly uneven:

A torqueT acting on a shaft creates an angular accelerationα that is proportional to that torque:

This is a rotational equivalent of traditional linear equation that ties forceF to massm and linear accelerationa:

In rotational motion the equivalent of massm ismoment of inertiaI. Similarly to how velocity is affected by acceleration,angular velocity is affected byangular acceleration. Let’s see how angular velocity of the crankshaft varies over time under a constant load:

As you can see the value fluctuates a lot. To reduce the angular acceleration and thus variation in angular velocity we have to increase the rotational inertiaI of the system. For that purpose a heavyflywheel is attached to the crankshaft with a bunch ofbolts:

Because theflywheel is heavy and has a large moment of inertia the variation in angular velocity of the crankshaft is reduced which makes the engine work more evenly:

Notice that theflywheel has gear teeth cut on its perimeter. Those teeth mesh with apinion gear that is powered by an electric starter motor when the engine is being turned on.

Once theflywheel starts moving its inertia helps to keep the crankshaft going which in turn lets the engine continue to operate on its own. Note that while the high inertia of theflywheel helps to smooth out the variation in angular velocity, it also comes at a cost – a very heavyflywheel is difficult to spin up so the engine becomes less responsive to throttle input.

In cars with manual transmission an engaged clutch presses against the flywheel to transfer the rotational motion to the transmission and further down to the wheels. Cars with automatic transmission don’t have a flywheel but instead they use aflexplate which is connected to atorque converter which serves as a source of large inertia to smooth out the engine’s efforts.

The journey through our engine ends here, but there are still many components needed to fully embed an engine in a car. The previously mentioned cooling system ensures the engine is kept at an appropriate operating temperature. Theintake andexhaust manifolds direct the flow of gases into and out of the cylinders. Anoil pump,oil filter, and oil passages in the engine block and cylinder head ensure all components are properly lubricated. Many modern engines also employ aturbocharger that uses the exhaust gases to increase the amount of air that gets pushed into the cylinders. All those components make sure that the engine can operate at expected level of power and efficiency.

Further Watching

Engineering Explained is one of the most popular channels dedicated to car technologies enthusiasts. Over the years Jason Fenske has covered a breadth of topics including acomparisons of injection systems,intake manifold design, and evenrotary engines.

PapadakisRacing has some great videos onengine assembly andteardowns. If you think you’d enjoy more videos from the latter categoryI Do Cars does in-depth deconstruction videos ofused engines.

How a Car Works is a fantastic video course on the operation of a car. In high quality episodes the presenter goes into a lot more details than what I’ve described here. While the course is paid, there are some free preview videosavailable on YouTube.

Final Words

Unchallenged for decades, the internal combustion engines in cars are slowly being supplanted by their electric equivalents, which are simpler, quieter, and more environmentally friendly.

Despite their drawbacks, classic engines still have something mythical about them – their intricate mechanisms are synchronized together to create carefully controlled conditions for harnessing fire in a truly Promethean way.