The Engine
A vehicle’s engine is the source of its power. That is, the engine does
the basic work needed to operate all the other parts of the vehicle. Almost
all automobiles contain four-stroke, gasoline-burning engines
FIGURE — A four-stroke, gasoline-burning automotive engine is shown here.
Although automotive engines come in a wide variety of
sizes, models, and designs, the basic operating principles of all engines
are the same. In this program, we’ll discuss how basic four-stroke engines
work, as well as the operation of a variety of engine designs.
Naturally, we can’t cover every possible type and design of engine in
this unit. However, once you thoroughly understand the operation
of a typical engine, you’ll easily be able to apply that knowledge to
virtually any type of automotive engine you may come across in the
future.
Modern automotive engines contain a variety of electronic and computerized
control systems that allow the engine to operate as efficiently
as possible. With the use of this modern technology, today’s
engines can perform in ways that weren’t possible years ago. Engines
today produce far more power (but fewer harmful exhaust emissions)
than similar engines from the past—all while using less fuel! This technology
is highly beneficial: the environment is kept cleaner, natural resources
are preserved, and the consumer gets a car that performs
better and more reliably.
As you learn more about engines and electronic control systems, you’ll
probably agree that these systems aren’t really that hard to understand.
In fact, many technicians find that engines equipped with electronic
control systems are easier to troubleshoot and repair than older
engines. No matter how you feel about electronic controls, the fact is,
they’re here to stay. Therefore, in order to be a successful auto repair
technician, you’ll need to understand how these systems work.
If you find the thought of working on electronic controls to be a bit overwhelming,
remember that these systems are only a part of the entire engine
system. The engine is made up primarily of mechanical parts that are
relatively simple in design and operation. Therefore, understanding how
the mechanical components of an engine operate is just as important as
knowing about the latest electronic control systems.
Basic Engine Operation
The engines that are used in automobiles are called internal-combustion engines. In an internal-combustion engine, fuel is burned inside the engine to produce power. The internal-combustion engine produces mechanical energy directly by burning fuel. In contrast, in an external- combustion engine, fuel is burned outside the engine. A steam engine/ boiler is an example of an external-combustion engine. The boiler burns fuel to produce steam, and then steam is sent to the engine to produce power. In an automotive engine, fuel is sent directly to the engine, where it’s burned inside to produce the power that’s used to run a vehicle. ...
