Evening capital news. (Boise, Idaho) 1901-1927, 1919-02-16

There is point, and quite an i'm
portant point, in connection with the
everyday use of motor car, that mo-
florists generally should take into con-
sideration when buying motor car.
That point Is how well the motor car
in question is adapted to the individ-
ual needs of the purchaser from the
standpoint of performance.
| To illustrate. A man who uses his
car entirely or largely within the lim-
its of a big city must use it within
certain wen defined speed limits in
order to comply with the ordinances
and the driving conditions encount-
cred. In traffic he must throttle down
to five or seven miles an hour, drive
| from 10 to 15 miles an hour through
the business district and from Is to 20
miles an hour in the outlying districts.
To give him good service, his motor
car, must perform economically and
efficiently within those speed limits,
and have sufficient reserve power to
accelerate smoothly and quickly at low
speeds.
On the other hand, farmer or any
other owner whose driving is done
tirely different conditions, as the ma
! jor part of his driving is done at
| speeds in excess of 20 miles an hour.
In some states the speed in the coun-
| try is confined by law to 25 miles an
hour. with an allowance of five miles
an hour for variation in speedometers,
thus giving maximum of 80 miles an
hour. In other states the law is less
| specific, merely stating that drivers
must drive with due caution" so that
the matter is left entirely to the drv-
er's judgment and smooth stretch of
road with no distractions may cause
him to speed up to so or go miles an
hour, if his car will go that fast.
CAR MUST PERFORM WELL.
These two cases represent the ex-
! tremes, but they are sufficient to IL
lustrate the point that a motor car for
miscellaneous city and country driving
must perform well at all speeds from
five to 60 miles per hour.
This presents a problem for the de-
signing engineers that is extremely
difficult of solution. 1t is purely a
question of motor design and manu-
+, facture.
give the desired result, particularly if
power and fleTibility can be COM
bined with economical operation. This
combination in the valve in-head mo-
tor Is an accomplished fact, and is re-
| sponsible for the performance that
puts Buick cars in q class by them
selves from mechanical standpoint.
In discussing internal combustion
motors, it is first necessary to get one
gact firmly fixed in mind, namely-that
they are all heat engines. In other
words, they derive their power by con-
verting the fuel used in operating them
into heat, and it is the expansion of
the heated gases resulting from each
explosion in the cylinders that supplies
the impulses necessary to run the mo-
tors.
HEAT UNITS MEAN POWER.
So, as far as the motor is con-
cerned, gallon of gasoline represents
so many heat units, and the greater
the percentage of these heat units that
can be converted into actual working
power, the greater the efficiency--or
economy-of the motor will be.
In engineering terms, this principle
is known as thermal efficiency.
Unfortunately, it is impracticable to
use all of the heat generated in such
a motor for power, because unless
some means of cooling the motor is
used the heat soon becomes so great
as to be destructive.
So, in making the cylinder castings,
water passages are cast around the
cylinders in such a manner as to al
low the excess heat to escape through
the cylinder walls into the water,
which in turn is cooled by the rada-
tor on the front of the car.
1t is quite evident, therefore, that the
less water jacketed space there is in n
motor, the greater the thermal (heaD
efficiency will be, because a smaller
area of the cylinder walls and COM
bustion chamber will be exposed to the
cooling influence of the water.
VALvE-IN-HEAD BEST DESIGN.
This brings us to the biggest reason
for the valve-in head design, because
the arrangement of the valves permits
of smaller, more compact combus-
ton chamber than is possible in either
the L-head or T-head type.
To make this stat ament still clearer,
1t should be understood that in all