El Paso herald. (El Paso, Tex.) 1901-1931, 1920-08-28

much gasoline and no more can be
added
To one cylinder fun OF airi What
is a cylinder full7 The answer is
that II all depends upon what you
I fill It from. Everybody knows that
when driving in very high attitudes
I loss OF power anyone who has driven
at 5000 feet elevation cannot fail to
have observed this.
Testing Airplane Engines
NOW the real reason for the. loss
[ OF power IS that owing 10 the rare
Tying effect OF the altitude. the pis-
ton can only suck in a smaller amount
OF air which viii only carry with
II smaller amount OF gasoline and
so VIII only produce more feeble
explosion OF course, the volume OF
air taken IN on the suction stroke is
just the same whatever the altitude,
but its weight IS less in proportion
as the altitude increases and the ratio
weight OF the fuel and the weight
OF the air necessary to ensure rea-
sonably complete combustion
Other things have the same effect
as attitude For instance. heat rare
fies air by expanding it SO that on
hot day the air charge which an en-
CINE can breathe in is smaller IN
weight than 1t would be on a cold
day In testing airplane engines i
is an invariable practice to make an
atmosphere. because the difference In
power is quite appreciate With a
500 horsepower engine variation OF
IS horsepower or more can easily
occur by reason Of nothing else but
change in the air Temperature
Motor Is Best at Night.
Here Is one OF tbs principal reasons
why an automobile motor does run
better at night Night air Is almost
always cooler than day air, so at
night the engine can get a heavier
charge and 50 produce a more power
ful impulse at each explosion
Not only Is the air taken into the
engine cooler and so heavier. but the
presence of a cooler atmosphere
means that the water cooling will be
more effective, that the motor viii in
itself be cooler.
This helps to make the charge
drawn in still better because the air
comes into the czrburetor cooler and
is heated less on its way through
the manifolds and within the cylinder
itself Also the oil viii be cooler. its
ter, and so there viii be less friction
in the motor.
Yet another thing IS that night air
often is damper than day air. The
poetic mists Of eventide cool down
the motor as well as perhaps making
the driver turn up his coat collar
Haven't you ever noticed how the
motometer drops back in a rain
shower? Well the effect OF damp
ness in the air Is Just the same
Difference IN Explosion.
Not only does the damp air help
by cooling slightly better in what
might be called burning quality. The
best kind OF an explosion is obtain
able from air that is not absolutely
dry. Dampness in the air within the
cylinder makes the explosion less vio-
lent The combustion, one might say,
IS slowed down ever so little 50 that
the gas gives more OF q push and
less Of a kick to the piston
Al these things are very small IN
degree and are limited in range. For
example, because cold air gives more
power than hot air lit does so only
as long as It is not so cold that the
gasoline cannot mix with and va
porize in It properly. Coming back
TO airplane engines again. the most
power seems TO be produced with air
somewhere around freezing point; II
colder the motor SHUTTERS and coughs.
but let it not be forgotten that this
is with very high-grade gasoline. One
can do little more than guess. but
the chances are an automobile motor
is at its normal best in an atmosphere
around 30 to 80 degrees
Auto Enjoys Night Air.
A British manufacturer Of motors
was the first to prove conclusively
that motors really did run better at
times other than the middle Of the
CINE which for some years was run
just a half hour or less at in the
morning. at noon and at in the eve
ming Averaging all the hundreds OF
runs. he found that there was not
much difference between the power
morning and evening, but that the
midday power always was noticeably
less
IN automobile engines It IS unlikely
that all the effects OF night air taken
together would make a difference Of
more than 5 percent. II indeed so
much, but this could easily represent
two or three horsepower and perhaps
just make the difference between
making some grade on high or not
making IL.
So when you fancy your car, Is run
ming better in the cool Of the eve
ming you don't have TO blame Il on
your own poetic state OF mind induced
by thoughts Of the Gray's elegiac
variety The chances are. the motor
really is enjoying the fresh night air.
KIssEL LINE OF CARS