Engines 101: The Basics of How Engines Work | Toyota

[00:00] just about everyone knows that a typical

[00:03] automobile gets its power from an engine

[00:05] under the hood

[00:06] but how many people can say they

[00:07] actually know how that engine works

[00:11] while a modern internal combustion

[00:13] engine is obviously an extremely complex

[00:15] piece of machinery

[00:16] the basic principle behind it is pretty

[00:18] simple let's take a closer look

[00:21] at a high level a gasoline engine can be

[00:23] thought of somewhat like an air pump

[00:25] except that the exhaust coming out is

[00:27] more of a side effect

[00:28] this pump's real purpose is to rotate an

[00:31] internal shaft which in turn rotates the

[00:33] vehicle's wheels

[00:35] it does this by connecting that shaft

[00:37] called a crankshaft

[00:38] to pistons that move due to a mixture of

[00:40] air and gasoline combusting inside their

[00:42] cylinders

[00:44] which creates a sort of chain reaction

[00:45] that keeps the engine turning

[00:48] before getting deeper into this process

[00:50] let's first touch on the two main parts

[00:52] of an engine

[00:54] on the bottom a lower block is home to

[00:56] the pistons

[00:57] cylinders and crankshaft the latter of

[01:00] which sends the engine's power out to

[01:02] the transmission and wheels

[01:04] and above the head contains the top of

[01:07] the cylinders

[01:08] and manages their airflow and combustion

[01:10] through valve train fuel injection

[01:13] and ignition systems so let's explain

[01:15] that part a little more

[01:17] you may have heard the term force drunk

[01:19] to describe a vehicle engine

[01:21] this refers to its four stages of

[01:24] operation

[01:26] first the piston moves down creating a

[01:28] vacuum in the cylinder chamber that

[01:30] pulls air in through precisely

[01:31] controlled intake valves

[01:34] next the valves close and the piston

[01:36] raises back up

[01:37] compressing all that air along with some

[01:40] gasoline that was mixed in from the fuel

[01:41] injection system

[01:44] now the fun part the ignition system

[01:46] creates a spark at the end of the spark

[01:48] plug

[01:48] creating a controlled explosion of

[01:50] compressed air and fuel that sends the

[01:52] piston back down

[01:55] then finally the piston moves back up

[01:58] pushing that spent air fuel mixture

[02:00] through the exhaust valves and out to

[02:01] the

[02:02] you guessed it exhaust pipes

[02:05] and since we're dealing with multiple

[02:07] cylinders with pistons all working from

[02:09] the same crankshaft

[02:10] each one essentially creates the

[02:12] four-stroke process for the next one

[02:14] pretty ingenious right now

[02:17] speaking of multiple cylinders let's

[02:20] talk about the various

[02:21] engine configurations four-cylinder

[02:24] engines are probably the most common

[02:25] design these days

[02:27] but who doesn't love a v6 or even a v8

[02:31] these terms simply refer to the number

[02:33] of cylinders in the engine

[02:34] and their layout nearly all

[02:36] four-cylinder engines have their

[02:38] cylinders arranged in a row

[02:40] called inline or straight but it's also

[02:43] pretty typical to see

[02:44] engines group their cylinders into two

[02:46] banks connected at an angle

[02:48] a v doing it this way effectively cuts

[02:50] the engine length in half

[02:52] enabling it to fit more easily under the

[02:54] hood so a v6

[02:56] three cylinders on either side creating

[02:59] a v-shape

[03:00] and what if that v-shape was opened up

[03:02] all the way

[03:03] a 180 degree angle well then you'd have

[03:06] what's called a boxer or flat

[03:08] engine design all right so what about

[03:12] those other numbers you always see

[03:14] 2.0 3.5 well that refers to the engine's

[03:18] displacement

[03:19] often simply thought of as its size

[03:22] that number is literally the volume in

[03:24] liters that the pistons displace with

[03:26] every engine cycle so essentially if you

[03:29] were to fill up the cylinders of a

[03:31] 2-liter engine with liquid

[03:33] it would take well 2 liters and if it's

[03:36] a 4-cylinder engine

[03:37] each one displaces half a liter

[03:41] so what's the end result of all this

[03:43] power

[03:44] the measurable output of an engine is

[03:46] called its torque

[03:47] basically the strength with which it

[03:49] turns its crankshaft

[03:51] torque is measured in pound-feet which

[03:53] as the name implies

[03:54] is the force created by one pound of

[03:56] weight at a distance of one foot

[03:59] imagine a one pound weight sitting at

[04:01] the end of a one foot wrench

[04:03] that nut is being turned with one pound

[04:05] foot of torque

[04:07] so now going back to the displacement

[04:09] concept bigger cylinders pull in more

[04:12] air and fuel typically resulting in more

[04:15] muscle

[04:15] they turn the crankshaft with more force

[04:18] which is perfect for large vehicles

[04:20] towing or even just spirited driving so

[04:23] now you're probably thinking isn't that

[04:25] horsepower

[04:26] well yes and no in fact horsepower

[04:29] doesn't technically exist okay

[04:32] yes that requires a bit of explanation

[04:35] horsepower is obviously a real thing but

[04:37] it's actually a calculation

[04:39] not a physical measurement like torque

[04:41] is it's basically torque over time

[04:45] so this means the faster that engine

[04:47] turns its revolutions per minute or rpm

[04:50] the more work it can do and the more

[04:52] horsepower it has

[04:54] put in extremely simplified terms torque

[04:56] times rpm

[04:58] equals horsepower but that doesn't mean

[05:01] making big horsepower is as simple as

[05:03] spinning the engine faster

[05:05] since that takes more and more energy as

[05:07] the engine speed increases

[05:09] and as that torque decreases the

[05:11] horsepower calculation eventually can't

[05:13] keep up either

[05:14] this is also why transmissions are so

[05:17] critical in keeping everything in the

[05:18] appropriate

[05:19] sweet spot but that's a topic for

[05:21] another video

[05:22] so that's the general idea behind

[05:25] internal combustion engines

[05:26] but this was just a high level look at

[05:28] the basics engines 101 if you will

[05:31] there's obviously a whole lot more to

[05:33] say about engine tech

[05:35] so be sure to check out the other videos

[05:36] in this series to learn more