Four-cylinder engines
This is perhaps the most popular
engine for ordinary cars of medium size. The torque obtained, as compared to a
single-cylinder engine, is much more uniform because two working strokes per
revolution are obtained.
Further, the balancing is also better. Apart from
this, the maintenance is also easier as compared to the engines and is much more
uniform because two working strokes per revolution are obtained. Further, the
balancing is also better. Apart from this, the maintenance is also easier as
compared to the engines with a larger number of cylinders.
The four cylinders are all in a line.
The second and third cylinders are in phase, while cylinders 1 and 4 are also
in phase, but in the direction opposite to 2 and 3. Thus the reciprocating
forces are also nearly balanced.
Six and eight-cylinder
engines
For higher
h. p. and smoother torque, the six and eight-cylinder engines have been used. Like
the four-cylinder engines, they have also been designed in the form of inline, v-type
and opposed-type configurations. Whereas out of the six-cylinder engine types,
the in-line type is most widely used, in the case of eight-cylinder engines, it is
the v-type which is almost universally in use. The angle between cylinder banks
is generally kept at 90o.
Its main advantages are:
The overall length of the engine decreases.
With 90o v-angel, good engine balance may be
achieved.
Even firing intervals are obtained.
Simple construction than the in-line type.
The disadvantages are that balancing is difficult and a more elaborate
intake manifold is required from a central carburettor. V-engines are also more
costly to manufacture because of the increased surfaces required to be machined.
V-8 engines
with smaller v angles, say 20o, have also been made. The advantages
of narrow v are less torsional vibrations and increased stiffness. However, the
valve operating mechanism is complicated.
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