Hello, my name is David and I would like to talk to you today about a machine
that has a direct influence on the lives of every person in this room. Many of us
take it for granted and the only time we pay it any mind is when it doesn’t work. I
am talking about, “The Internal Combustion Engine”. (The OMG slide)
I started working on engines at the age of 16. I have worked in the automotive
field professionally for over 20 years. I have earned a California State Smog
license. I am certified in engine rebuilding, fuel and ignition systems, by Hyundai
Motors. I am certified in power train and suspension by Honda of America. After
moving to Utah, I earned my Utah County Emissions license and my Utah State
Safety Inspection license. Last spring break, I took a 4 hour written and 7 hour oral
and practical exams and received my FAA Airmen Mechanics license with an
Airframe rating and I will have my Power Plant rating by Christmas.
(Slides of car than under hood)
Most of you, on a daily basis, walk out of your house, get into a car or truck,
turn a key and off you go without even a single thought about what is going on
underneath your hood. I am going to explain and hopefully help you understand
the synchronized dance of explosions, heat and expanding gases that occur to
make it possible for you to get from point A to point B.
An internal combustion engine converts heat energy from fire into workable
power. We need 3 elements to create fire and they are heat, fuel, and oxygen.
(Slides of lightning)
The heat source is supplied by a hot spark which is induced by the ignition
system. This system consists of a 12 volt battery, ignition switch, a coil, a
distributor, sparkplug wires, and sparkplugs. That lightning is not too much of an
exaggeration because 12 volts goes into the coil, but 25 to 30 thousand volts
come out the other side.
(Slide of gas can)
The fuel source, in this case gasoline is stored in a fuel tank and is pumped to the
carburetor or fuel injection system as it is needed.
(Slide of clouds)
The oxygen is supplied by the atmosphere and is directed into the engine through
an intake manifold and filtering system.
(Slide of Hemi)
Now we have the 3 elements to make fire, we need an environment that will
help us control the explosions to obtain the maximum power and economic fuel
(Slides of engine parts)
The engine block is the housing or body of the engine that holds all the
components that make this dance possible. The crankshaft is the backbone of the
engine. It transfers the power being made by the engine to the device that makes
the vehicle move, whether it is a propeller on an airplane or a transmission that
makes your wheels turn. Along with the crankshaft, we have connecting rods that
attach the pistons, and a camshaft that operates the valves.
The engine in your vehicle is what they call a 4 stroke engine. A stroke is the
movement of the piston from top dead center to bottom dead center, or vice-
versa. We have the intake stroke, compression stroke, power stroke, and exhaust
stroke. During the intake stroke, the intake valve opens, allowing the air-fuel
mixture to be drawn into the cylinder by the downward motion of the piston,
than it closes creating an air tight seal. The compression stroke squeezes the air-
fuel mixture up against the cylinder head where the sparkplug ignites it. The
explosion releases heat and the pressure from the expanding gases force the
piston downward producing the power stroke. The exhaust valve opens and the
upward motion of the piston pushes the exhaust gases out of the engine. This is
called, “The Otto Cycle”.
In closing, I would like to say that this wonderful machine has made it possible
for human beings to travel vast distances in mere hours where it took our
ancestors days, perhaps weeks to travel. So the next time, you’re sitting
comfortably behind the wheel of your car, doing 90 down the freeway, just
remember the controlled chaotic dance the being performed underneath your
hood. Thank you. Are there any questions?