1. DESCRIPTION
1.1 General Information
The
power
output
of
an engine
is
governed by
three
factors, namely pressure, speed and
the
displace-
ment.
Applied formula:
p::::::
p x n x V
H
P
;::
Output
************
p
;::
Pressure
n
;::
Speed
VH
;::
Displacement
The
power
output
of
a specific engine can be increased by raising
the
speed
or
pressure. Since
the
speed
is
limited by
the
occurence
of
inertia force, it
is
preferred
to
keep pressure
"p"
as high as pos-
sible.
Pressure
"p"
depends on
the
compression ratio and volumetric efficiency (cylinder charge). Since an
increase
in
compression ratio will only
produce
a relatively small rise
in
pressure, it
is
obviously
better
to
optimize
the
cylinder charge. This can be accomplished by precompression
of
the
intake air.
The
cylinder charged will be increased even more by also cooling
the
precompressed air.
The
precompres-
sion
of
intake air
is
known
as supercharging. An engine can be supercharged with a compressor
or
an
exhaust gas turbocharger.
The
application
of
a compressor
is
disadvantageous since operation of
the
compressor uses some
of
the
engine's power
output.
Supercharging with an
exhaust
gas turbocharger,
on
the
other
hand, uses
mecllanical energy converted from
part
of
the
energy contained
in
exhaust
gases
to
drive
the
compres-
sor.
5
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