Arizona republican., 1922-04-23
Brilliant Exposition of 1922 Cars Tuesday Night
DECLARES TREND.
IS TOWARD FOUR
CYL|NDERMOTOR

The trend in the medium priced
field toward the four cylinder prin.
ciple and general simplification OF
chassis. is more apparent to visitors
at this years shows than ever before
state NJ L. Burkhead, of the Smith
Motor Sales company. The result OF
this trend has been to intensity in
terest in those cars. whose superior.
ity in the four cylinder field has beer
established over a period of years
1t has directed particular attention
to a car like the Hupnobile. which
since 1908. has steadily developed the
iour-cyiinder motor to its present
perfection.
discrimination of the Hupmobile.
chassis at the New York show first
gives the impression Of simplicity
and accessibility, which is thorough
" confirmed by closer inspection.
10 those who owing to the number OF
interested visitors at the HupmobiIe
booth were unable to get as n11lel1
information as they desired. the fol-
lowing description will prove of IN
terest:
The Hupmobile four-cylinder mo-
tor-312" bore by 5ks stroke-is of
the L-head type, having intake and
exhaust valves on the same side. The
cylinder displacement is IS3 cubic
inches The compression is 20 pounds
guage pressure to the square inch at
1000 r. p. NJ. The power curve Of the
Hupmobile motor is such that the
point of maximum power is sustained
over a wide range of motor speeds
without loss.
Cylinders and crank case are cas-
together in a block of noticeable
symmetry and rigidity. The cylinder
mead IS detachable, giving easy access
70 combustion chamber and valves
Inc crankshaft is tested for static
and dynamic balance. 1t is of ample
diameter extra heavy. and Of short
length between bearings. giving rig
ldity- It runs in three large bearings
or the best grade phosphor bronze
with special high speed babitt lin.
ing. These bearings are exception
ally large for a motor of this size
and a crankshaft of this length
making the crankshaft unusuaIiy
rigid and reducing motor vibration.
All bearings are carefully fitted il
crank case after which they are
bored to insure true alignment. Fol.
lowing this they are fitted TO crank
smart by an exact and careful process
OF hand scraping. They are split and
provided with Iaminated shin1s.
which makes them easy of adjust
ment
The flywheeI Is tested for dynamic
balance then attached to the crank
smart, and the whole assembly in
again tested for perfect rotating bal
ance.
The maximum thrust per explosion
on each piston is approximately
1000 pounds. The connecting rods
transform this force into the even
power and smooth running of the
cfankshaft. They are I17s inches
between centers. of I-beam shape.
carefully machined for lightness and
balance. The material and construc-
tlon OF the connecting rods give max
mum rigidity and strength with the
necessary lightness in weight. The
connecting rod bearings, are of phos-
phor broze. babbitt lined, and are
scraped and fitted by hand with the
same care as crankshaft bearings.
The length of the connecting rod
compared with the strolxe-11TS inch
es to 55s inches-deserves attention.
as this unusual length reduces the
pressure or thrust OF the piston
against the cylinder walls, by reason
line.
The pistons are special light cast
and weigh but 20 ounces each. In
shape they are of the hour glass
nigh speed type. and are carefully
ground to less than .001 inch limits
on bearing surface. They are fitted
With three rings; two above the
piston pin, and one below which
serves to keep oil out of combustion
chamber. The piston pin lis made of
steel carefully heat treated. hardened
and ground. These hollow pins are
clamped in the rod, and turn in the
piston, giving the advantage of an
extra bearing surface
The reason why all reciprocating
parts are of light weight and care
fully balanced is evident when YOU
consider that the pistons stop and
start approximately IS times per sec-
ond when the motor is running az
speed.
The crank case and cylinders are
In single casting. of the best grade
special analysis cylinder iron, res
rigid. Casting is ''seasoned9
for sufficient time, to relieve internal
stress. and insure bearing alignment
The working parts OF the motor are
protected from dirt and mud by
crank case, and a two-piece shield
which has sections along the sides
OF the motor below the frame and
across the front: the advantage of
this construction are extreme motor
accessibility, and more efficient cool
ing. The engine has three point sus-
pension.
The cylinders are ground on an in
ternal grinder, a process more ex-
pensive but giving much more salts
fatcory results than roaming. This
method gives a glass-like surface te
the cylinder walls. insuring long life.
and preventing compression loss be-
cause. OF closer fitting pistons. The
cylinder head gives access
IN manufacturing to both ends OF
the cylinder bore. and allows the use
1f internal dial indicators for meas
Iring bore precisely to 0005 inch
imits at top and bottom; the cylin
Ter block being open both ends. rem
1ers the casting of the block more
Uniform, and inspection more exact.
The combustion chamber of snecial
improved shape. gives large mixture
yolume over the valves. This con-
,truction has been carefully designed
o take full advantage of the inlet
yas turbulence. and gives a mower
md efficiency hitherto obtained only
With complicated valve systems.
S. A. E. horsepower rating is 1853.
The actual brake horsepower devel-
ped is naturally much greater.
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FAVE IT To THEM