Evening capital news. (Boise, Idaho) 1901-1927, 1919-02-09

With the advent of the automobile It
soon became necessary to have some
standardized method Of measuring the
power of a gasoline engine and ex-
pressing the result in terms that would
convey an Ineligible meaning.
The standard settled upon was the
arbitrary fixed unit horsepower which
was already in use for expressing the
power of steam and other engines. AS
applied to motors, one horsepower is
the power required to lift $4,000 pounds
one foot in one minute.
But because of the peculiar mechani-
cal laws governing it's performance, the
power of an internal combustion en-
CINE varies at different motor speeds.
rising sharply as the motor speed is
increased until a certain number of
revolutions per minute have been at
tanned and then falling onf Immediate
ly after the maximum has been
reached.
So far this reason, the National Au-
tomobile Chamber of Commerce has
adopted what was formerly known as
the A. l.. A. M. rating. D is the CYL
Under rating in inches, n the number
of cylinders. and 25 constant, based
on the average view of eminent engi-
neers as to fair, conservative rating
for a four-cycle motto rat 1000 feet per
minute piston speed.
Upon analysis, it will be seen that
this method of computing horsepower
VIII OF necessity be quite inaccurate
In many cases. For one thing, it does
not take into consideration the stroke
of the motor, the size of the valves,
the valve timing nor many other fea-
lures of design that have a great bear
Ing on the actual power that q motor
VIII develop. or rather to put it in
another way, it places all motors on
owner wishes to know on the vital
subject of performance. Actual test
Ing against the electric dynamometer
tells u great deal more to the ex-
perienced engineers because from it
ne can make up a chart showing the
power of the motor, illustrating it's
power al the different speeds in the
disable speed area. For example, two
motors might show the same maximum
and minimum power at high and low
the same plano as far as these impor-
tant items are concerned.
Further. this arbitrary formula tells |
practically nothing that the motor car
speeds ON the chart, yet the difference
In the power curves throughout the in
termediate speeds may show a differ |
ence in favor of one motor of several |
horsepower, which would give that |
motor an immense advantage in hill |
climbing, heavy pulling and ordinary
driving performance.
This is really where the fine points
OF design come into play, both in per-
Torrance and economy The valve-in
mead motor. as any owner will
gladly attest, has a power curve that
adapts it admirably to miscellaneous
driving and gives it exceptional pulling
power over wide range of motor
speeds.
The development of this motor has
been going steadily on for nearly 20
years, and no phase of design has
peen neglected in the effort to improve
IL In every way possible. 1t is the con-
sistency with which this work has been
carried out, improving every detail of
design in every possible way, that has
made the motor what it is today. But
back of all these things is the valvc-in-
mead principle of design, which, more
than any other individual feature, ex-
plains the power an deconomy of the
motor.
In discussing internal combustion
motors. it is first necessary to get one
TACT FIRMLY fixed in mind, namely. that
Ihey arc all heat engines. In other