WEBVTT 00:00:00.000 --> 00:00:03.480 I'm Jake O 'Neill, creator of Animagraffs, 00:00:03.480 --> 00:00:05.700 and this is how a car engine works. 00:00:07.280 --> 00:00:08.960 Let's start at a single piston, 00:00:09.640 --> 00:00:12.820 the powerhouse of the engine, and work our way outwards. 00:00:14.920 --> 00:00:16.200 The 4 stroke cycle. 00:00:17.520 --> 00:00:19.820 When a piston travels to the end of its range, 00:00:20.460 --> 00:00:23.080 whether up or down, that's a stroke. 00:00:24.740 --> 00:00:28.980 Car engines use a 4 stroke cycle, and it goes like this. 00:00:30.000 --> 00:00:31.360 First, intake. 00:00:32.100 --> 00:00:33.080 The piston descends, 00:00:33.920 --> 00:00:37.220 sucking an air-fuel mixture into the cylinder through the 00:00:37.220 --> 00:00:40.720 intake port, with both intake valves open. 00:00:42.280 --> 00:00:43.740 Next, compression. 00:00:45.080 --> 00:00:48.420 With all valves closed, the piston comes back up, 00:00:48.880 --> 00:00:51.420 compressing the fuel and air mixture for more powerful 00:00:51.420 --> 00:00:51.920 combustion. 00:00:54.700 --> 00:00:56.700 Then, the power stroke. 00:00:56.700 --> 00:01:00.960 An electrical spark ignites the compressed fuel and air 00:01:00.960 --> 00:01:01.380 mixture, 00:01:02.220 --> 00:01:04.879 and the resulting combustion forces the piston to the 00:01:04.879 --> 00:01:06.100 bottom of the cylinder again. 00:01:07.480 --> 00:01:10.660 A connecting rod transfers this power to the crankshaft. 00:01:12.960 --> 00:01:14.160 Finally, exhaust. 00:01:15.220 --> 00:01:16.940 The piston comes back up, 00:01:17.560 --> 00:01:20.300 pushing the spent mixture out through open exhaust valves 00:01:20.300 --> 00:01:25.660 and the exhaust port connecting multiple pistons. 00:01:26.700 --> 00:01:29.940 For smooth power delivery, pistons take turns firing. 00:01:30.820 --> 00:01:35.980 The firing order for this engine is one, three, four, two. 00:01:37.340 --> 00:01:39.940 Camshafts, with specially shaped cams, 00:01:40.600 --> 00:01:42.980 push spring-loaded valves open in turn. 00:01:46.020 --> 00:01:49.820 Cam gears and a timing belt or chain links everything to 00:01:49.820 --> 00:01:52.600 the crankshaft, and it all spins together. 00:01:56.700 --> 00:01:59.960 The crankshaft translates piston power out of the engine. 00:02:00.600 --> 00:02:04.240 It has counterweights to balance against the pistons for 00:02:04.240 --> 00:02:05.500 perfectly smooth revolutions. 00:02:07.920 --> 00:02:09.460 This is what RPM means. 00:02:10.180 --> 00:02:12.700 We're counting the number of full crankshaft revolutions 00:02:12.700 --> 00:02:13.300 per minute. 00:02:16.300 --> 00:02:20.900 The engine block holds the crankshaft and cylinders and the 00:02:20.900 --> 00:02:24.700 cylinder head holds valves, ports, cams, etc. 00:02:25.700 --> 00:02:29.720 The geared flywheel sits at one side of the crankshaft for 00:02:29.720 --> 00:02:30.840 connection to a transmission. 00:02:32.000 --> 00:02:34.280 It's also where the starter connects to the system. 00:02:35.820 --> 00:02:39.400 This engine has four cylinders arranged in a single row, 00:02:40.220 --> 00:02:42.580 but there are many other possible configurations, 00:02:43.460 --> 00:02:45.980 like six cylinders with three on each side, 00:02:46.540 --> 00:02:48.540 angled in a v-shape, or eight. 00:02:49.900 --> 00:02:51.280 Despite different design goals, 00:02:51.520 --> 00:02:53.560 the basic engine parts are all there. 00:02:55.220 --> 00:02:57.500 Now let's look at other systems that support this 00:02:57.500 --> 00:02:58.440 combustion process. 00:03:02.700 --> 00:03:03.940 Air intake. 00:03:05.960 --> 00:03:11.720 Air comes in through the air filter and then into the 00:03:11.720 --> 00:03:15.020 intake manifold where it mixes with fuel before being 00:03:15.020 --> 00:03:18.260 sucked into individual cylinders through intake ports. 00:03:25.000 --> 00:03:25.740 Fuel. 00:03:29.860 --> 00:03:36.820 The fuel pump carries gas from the tank through a fuel 00:03:36.820 --> 00:03:42.200 filter to the engine where fuel injectors emit a precisely 00:03:42.200 --> 00:03:45.500 timed spray of gas into the intake port. 00:03:54.200 --> 00:03:54.940 Cooling. 00:03:55.920 --> 00:03:59.260 Engines get very hot during operation and require a cooling 00:03:59.260 --> 00:03:59.720 system. 00:04:02.380 --> 00:04:04.800 Coolant channels around the cylinders and through the 00:04:04.800 --> 00:04:09.200 cylinder heads carry a special liquid called antifreeze to 00:04:09.200 --> 00:04:11.440 keep temperatures within safe operating range. 00:04:12.980 --> 00:04:15.640 It's called antifreeze because it won't freeze in icy 00:04:15.640 --> 00:04:15.960 weather. 00:04:18.980 --> 00:04:20.519 After cooling hot engine parts, 00:04:20.839 --> 00:04:22.260 coolant circulates through the radiator. 00:04:23.320 --> 00:04:26.160 The radiator has a network of small tubes and fins. 00:04:27.320 --> 00:04:32.220 Coolant passes through these channels while air pulled in 00:04:32.220 --> 00:04:35.300 by the radiator fan blows by the tubes, 00:04:35.740 --> 00:04:37.960 cooling the hot liquid for recirculation. 00:04:44.080 --> 00:04:47.740 A water pump keeps the coolant system flowing and properly 00:04:47.740 --> 00:04:48.340 pressurized. 00:04:51.580 --> 00:04:54.100 The thermostat regulates coolant temperature by either 00:04:54.100 --> 00:04:57.580 routing coolant back through the engine or to the radiator 00:04:57.580 --> 00:04:58.720 for further cooling. 00:05:02.100 --> 00:05:02.740 Electrical. 00:05:05.720 --> 00:05:09.180 The spark plug delivers the electrical spark that ignites 00:05:09.180 --> 00:05:10.920 the fuel-air mixture for combustion. 00:05:11.720 --> 00:05:14.340 The metal core is insulated from the outer metal casing 00:05:14.340 --> 00:05:15.120 with porcelain. 00:05:16.120 --> 00:05:18.580 The spark jumps between these conductive surfaces. 00:05:25.000 --> 00:05:28.240 A coil pack delivers electrical current to the spark plugs 00:05:28.240 --> 00:05:33.300 as directed by the ECM, or Engine Control Module. 00:05:34.560 --> 00:05:37.440 The ECM is a computer that directs many core engine 00:05:37.440 --> 00:05:41.680 functions like spark timing, valve open and close timing, 00:05:42.280 --> 00:05:44.160 air to fuel ratio, etc. 00:05:45.560 --> 00:05:47.880 The alternator works like a power generator, 00:05:48.540 --> 00:05:51.640 converting the engine's mechanical energy into electricity 00:05:51.640 --> 00:05:55.520 to charge the battery or run other electrical systems while 00:05:55.520 --> 00:05:56.280 the engine is running. 00:05:59.000 --> 00:06:02.140 The battery provides power to the starter for engine start. 00:06:07.780 --> 00:06:08.380 Oil. 00:06:08.380 --> 00:06:12.120 Motor oil is used to lubricate, clean, prevent corrosion, 00:06:12.380 --> 00:06:12.960 improve sealing, 00:06:13.560 --> 00:06:16.400 and cool the engine by carrying heat away from moving 00:06:16.400 --> 00:06:16.880 parts. 00:06:19.920 --> 00:06:22.720 Rings around the top of the piston head keep oil out of the 00:06:22.720 --> 00:06:23.660 combustion process, 00:06:24.220 --> 00:06:26.940 while otherwise allowing the cylinder to be lubricated. 00:06:28.140 --> 00:06:31.200 Oil galleries are channels through the engine block and 00:06:31.200 --> 00:06:34.160 cylinder head that carry oil to various engine parts. 00:06:37.680 --> 00:06:40.280 Oil flows through the engine and back to the oil pan for 00:06:40.280 --> 00:06:41.080 recirculation. 00:06:44.540 --> 00:06:47.440 Oil rests in the oil pan when not in circulation. 00:06:49.160 --> 00:06:52.460 The oil pump keeps oil properly pressurized and flowing. 00:06:54.880 --> 00:06:58.260 And the oil filter keeps oil clean from contaminants. 00:07:03.760 --> 00:07:04.180 Exhaust. 00:07:08.920 --> 00:07:12.380 The exhaust manifold collects gases from multiple cylinders 00:07:12.380 --> 00:07:13.700 into one pipe. 00:07:16.400 --> 00:07:19.560 Exhaust flows through the catalytic converter which 00:07:19.560 --> 00:07:23.680 captures toxic chemicals in engine exhaust and then out 00:07:23.680 --> 00:07:25.960 through a muffler that reduces exhaust noise. 00:07:29.300 --> 00:07:30.180 And finally, 00:07:30.800 --> 00:07:33.580 here's the full functioning engine with all the basic 00:07:33.580 --> 00:07:34.800 systems we've discussed.