The Washington times. [volume] (Washington [D.C.]) 1902-1939, 1908-11-29
FOREIGN HORSEPOWER
RATING NOT PRACTICAL
Limiting Size of Bore Does Not Prevent Freak Racing
Cars-Americans Suggest Classification by
Cyclinder Volume.
BY ANDREW L. RIRER.
President Mechanical Branch, A. L. Il. VI.

Every owner OF a car should have
clear conception of what a horsepower
is
The term is a relic of the time of
James Watt who invented the first
practical type of steam engine. He
wanted a term that would define power
or rate of doing work, that is TO say.
work divided by time. lie made eN-
periments and found that a powerful
drayhorse could do all day long work
equivalent to 5000 pounds raised one
foot per minute.
Competent designers know accurately
what power, at the least. good saso-
lene motor of a given size should de-
Velop- The required size, weight, run
ming qualities and life of the motor
are also pretty well understood That is,
IL is clear within relatively narrow lines,
what type of motor il is reasona bile TO
put in a car to be used by the public
ana also what a fair ana conservative
rating for a given size motor at a given
sure should also come in for ConsideTa-
A. L. A M Formula.
The A L. A. NJ. horsepower formula
was adopted after much consideration
by, and the almost unanimous opinion
of, the association engineers. And
have been continually gratlfied by its
adoption. Various bases for standard
rating were considered. Finally a
formal vote of all the engineers was
taken on the question of what is "a fair
conservative rating for d given size
four-cycie single acting motor at q
given piston speed. one thousand feet
per minute had previously been agreed
upon as proper piston speed 10 as
The average view was so nearly in ac-
cord With the results the formula there
tOrOre adopted by the Royal Automobile
Club of England tthe diameter OF the
Der OF cylinders, divided by the constant
TWO and one-half, equals horsepower,
that II was decided TO adopt this for
mulds conforming 10 an existing stand
ard. 50 avoiding further confusion ia
subject It was sought to clarity
superficial critics of this formula at
times fail 10 bear in mind that the
application of the formula recommended
by the Association of Licensed AutOmO-
bile Manufacturers, is based on ]. 6J1
Teet per minute piston speed. Neither
ought II be necessary TO point out that
motor developing on the block s. per
cent more than the required power by
the formula, is no occasion for surprise,
lit is looked for.
Contest Ratings.
The A. l. a. NJ. horsepower formula
was not intended primarily TO be used
in racing. but there is no reason why il.
OF an analogous principle cannot he
used equally we'll as a basis of contests
of any character. We see n the recent
''fOuT-inCh' race in England. in the de-
CiSiOn 10 limit only the engine bore OF
cars entered in international racing, and
in specially constructed single cylinder
racing cars abroad, d marked encou--
agemeuJ OF cars which would never be
built for touring purposes only.
The obvious sensible way of limiting
the power of racing motor is 10 +mit
she cylinder volume, and not the bore or
the stroke alone. The limitation OF the
engine bore under the Grand PTiX rules
is very wise. but the stroke also should
have been limited for engine strokes
of freakish length are the inevitable re-
suit. The amount of compression pres
sure should also come In 70 rConsidera-
ton
All racing cars built abroad for the
season 81 1905, by virtue of an iuteTua-
tiOual ruling. were restricted in design
as 10 their cylinder bore For the
Grand FriE and other events, intended
Tor large cars, the bore was 81 inches:
for the English Isle OF Man contest the
Limitation was 4 inCheS-thUs the name,
"FOur-InCh Race Similarly the bore
OF the cars constructed for the small
car race run on the uay preceding the
Grand PTiX were restricted
IL spite OF these limitations the cars
were speedy and notably high averages
we're made In fact, the average time
made by the winner of the ElorO Cir
cult is new record, faster work than
has even been accomplished before
with a motor Of unlimited bore and
stroke. The Grand PTiX vas won at an