Hudson Super Six 1916 Reference Book page 8

This was caused by unbalanced forces. The introduction of the high speed, four-cylinder motor with the
counterbalanced crank shaft, largely a European product intended for racing and extremely expensive to produce,
was brought about through the realization of this defect.
American manufacturers having turned their attention to the solution of this problem by means of the
six-cylinder motor, it was for a time believed that a solution had been found. However, it soon developed that
motors which were more economical to build and maintain, and which delivered proportionately more power,
could be obtained with six cylinders if the reciprocating parts were lightened and the speed increased. Vibration
was still a limiting factor.
Some manufacturers now devoted their attention towards further lightening the reciprocating parts in an effort
to reduce the -pressure for the working stroke for each individual cylinder. This had to be brought about through
reduction in the bore and under such conditions, the power of the motor would materially decrease. Therefore,
more cylinders were added and the V-type eight and twelve cylinder motor was developed.
For some time, the Hudson engineers had been viewing the problem with the same knowledge as their
associates who were favoring the smaller bore motor. But they set about eliminating the trouble by a revision of
the crank shaft construction, rather than by using more cylinders in order to decrease the weight of the
reciprocating parts. This latter method necessitated many complications which they considered contrary to good
practice.
The result has been a crank shaft which, by means of a patented system of eliminating vibration, makes a
motor low in absorbed horse power and proportionately high in transmitted horse power.
As an illustration, the average six-cylinder motor in use today, having a capacity of about 300 cubic inches,
seldom develops more than 55 horse power at 2000 revolutions. It is not possible to run such a motor
continuously at speeds of 2500 revolutions, as this is beyond the critical point at which the motor would tend to
self-destruction very rapidly. Such motors while transmitting only approximately a maximum of 55 horse power,
would be actually doing work to the extent of 80 horse power for they average approximately 25 horse power in
internal friction at 2000 revolutions. The absorption of power within the motor itself is the limiting factor in the
life of that motor, in addition to limiting the power transmitted. By reducing the absorbed horse power, we obtain
a proportional increase in the transmitted power, provided the design of other parts of the motor is nearly perfect.
This new design may well be called an invention because it enables us to get abnormal results from a motor of
only six cylinders - 288 cubic inches.
In other details, the motor varies but little from general practice, except perhaps that it contains a greater
number of refinements, is excellently proportioned as to bearings, valve adjustments, etc., and is extremely simple
and accessible.
In order to meet the increased motor speed made possible through the new type of motor, it has been
necessary to increase the area of valve openings 20% and 13% on the inlet and exhaust respectively. The crank
shaft main bearings-of which there are four-have been increased 51/0 in diameter and considerably more in area,
the bearings being 2-9/16", 2-1/8", 2-1/8" and 3-3/8" front to rear. This as compared with the Six-40.
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