I'm Jake O 'Neill, creator of Animagraffs,
and this is how a car engine works.
Let's start at a single piston,
the powerhouse of the engine, and work our way outwards.
The 4 stroke cycle.
When a piston travels to the end of its range,
whether up or down, that's a stroke.
Car engines use a 4 stroke cycle, and it goes like this.
First, intake.
The piston descends,
sucking an air-fuel mixture into the cylinder through the
intake port, with both intake valves open.
Next, compression.
With all valves closed, the piston comes back up,
compressing the fuel and air mixture for more powerful
combustion.
Then, the power stroke.
An electrical spark ignites the compressed fuel and air
mixture,
and the resulting combustion forces the piston to the
bottom of the cylinder again.
A connecting rod transfers this power to the crankshaft.
Finally, exhaust.
The piston comes back up,
pushing the spent mixture out through open exhaust valves
and the exhaust port connecting multiple pistons.
For smooth power delivery, pistons take turns firing.
The firing order for this engine is one, three, four, two.
Camshafts, with specially shaped cams,
push spring-loaded valves open in turn.
Cam gears and a timing belt or chain links everything to
the crankshaft, and it all spins together.
The crankshaft translates piston power out of the engine.
It has counterweights to balance against the pistons for
perfectly smooth revolutions.
This is what RPM means.
We're counting the number of full crankshaft revolutions
per minute.
The engine block holds the crankshaft and cylinders and the
cylinder head holds valves, ports, cams, etc.
The geared flywheel sits at one side of the crankshaft for
connection to a transmission.
It's also where the starter connects to the system.
This engine has four cylinders arranged in a single row,
but there are many other possible configurations,
like six cylinders with three on each side,
angled in a v-shape, or eight.
Despite different design goals,
the basic engine parts are all there.
Now let's look at other systems that support this
combustion process.
Air intake.
Air comes in through the air filter and then into the
intake manifold where it mixes with fuel before being
sucked into individual cylinders through intake ports.
Fuel.
The fuel pump carries gas from the tank through a fuel
filter to the engine where fuel injectors emit a precisely
timed spray of gas into the intake port.
Cooling.
Engines get very hot during operation and require a cooling
system.
Coolant channels around the cylinders and through the
cylinder heads carry a special liquid called antifreeze to
keep temperatures within safe operating range.
It's called antifreeze because it won't freeze in icy
weather.
After cooling hot engine parts,
coolant circulates through the radiator.
The radiator has a network of small tubes and fins.
Coolant passes through these channels while air pulled in
by the radiator fan blows by the tubes,
cooling the hot liquid for recirculation.
A water pump keeps the coolant system flowing and properly
pressurized.
The thermostat regulates coolant temperature by either
routing coolant back through the engine or to the radiator
for further cooling.
Electrical.
The spark plug delivers the electrical spark that ignites
the fuel-air mixture for combustion.
The metal core is insulated from the outer metal casing
with porcelain.
The spark jumps between these conductive surfaces.
A coil pack delivers electrical current to the spark plugs
as directed by the ECM, or Engine Control Module.
The ECM is a computer that directs many core engine
functions like spark timing, valve open and close timing,
air to fuel ratio, etc.
The alternator works like a power generator,
converting the engine's mechanical energy into electricity
to charge the battery or run other electrical systems while
the engine is running.
The battery provides power to the starter for engine start.
Oil.
Motor oil is used to lubricate, clean, prevent corrosion,
improve sealing,
and cool the engine by carrying heat away from moving
parts.
Rings around the top of the piston head keep oil out of the
combustion process,
while otherwise allowing the cylinder to be lubricated.
Oil galleries are channels through the engine block and
cylinder head that carry oil to various engine parts.
Oil flows through the engine and back to the oil pan for
recirculation.
Oil rests in the oil pan when not in circulation.
The oil pump keeps oil properly pressurized and flowing.
And the oil filter keeps oil clean from contaminants.
Exhaust.
The exhaust manifold collects gases from multiple cylinders
into one pipe.
Exhaust flows through the catalytic converter which
captures toxic chemicals in engine exhaust and then out
through a muffler that reduces exhaust noise.
And finally,
here's the full functioning engine with all the basic
systems we've discussed.