From the customers' point of view, power and economy are the most
important factors considered in an automobile engine. Other engine
features are of lesser importance. Discussion of the Hurricane engine
will follow this pattern. A list of technical specifications is at the
end of the section.
POWER
The Hurricane stands out as one of the most highly developed and
perfected four-cylinder engines in the automotive industry. Since its
wartime introduction its performance has been steadily improved,
vibration cut down, and horsepower increased. Today the Hurricane engine
develops 75 horse power and 114 pounds of torque from its 134.2 cubic
inch displacement and 6.9-1
compression ratio. This means steady power performance with great
economy for the bulk of the jobs to be done by Willys utility vehicles.
In those countries where fuel costs are high, the four-cylinder
Hurricane gets more miles per gallon of non-premium gas. This spells
economy.
This engine can also deliver 33 horsepower from a power take -off
point for continuous operation. In the Universal 'Jeep' it can provide a
drawbar pull of 2317 pounds. This engine i s designed to do the job and
really take punishment.
HURRICANE ENGINE HIGHLIGHTS
CYLINDER HEAD
The combustion chamber is specifically designed to achieve a fine
compromise between high compression and the danger of pre-ignition of
fuel.
When compression is too high the fuel ignites on the compression
stroke, before the spark plug fires.
This results in back pressure that can cause great damage to the piston
and rings. On the other hand, too low compression means wasted fuel and
power. The Hurricane engine's 6.9-1 compression ratio prevents all of
this. See illustration below.
When the engine is used at elevations above 5000 feet and a good
grade of gasoline is available, a special 7.4-1 cylinder head is used to
offset the drop in atmospheric pressure.
Another feature of the Hurricane cylinder head is the built-in intake
manifold. The fuel mixture leaves the carburetor and enters a passage in
the cylinder head on its way to the cylinder chambers. Here the fuel
mixture is warmed by the adjacent water cooling system passages in the
cylinder head. This preheating means more efficient combustion and more
power.
VALVES
The F-head design means the exhaust valves are further away from the
intake valves. This construction permits the use of larger exhaust
valves resulting in faster, more positive ejection of burned gases.
There is no residue to cut power. Since the intake valves are also
larger they allow a better flow of fuel air mixture. This results in a
more uniform fuel mixture entering the cylinder.
Both intake and exhaust valves are made of chromium steel alloys for
greater heat resistance. In addition the exhaust valve guide is
chamfered to provide an area for carbon that would normally gather and
cause sticking, or improper closing.
A further precaution in this respect is the incorporation of
valve rotators on the valve stems. With each stroke the valve is turned
slightly resulting in uniform heating and longer valve life. This also
wipes off any foreign matter that may have lodged on the valve seat.
By varying the loop spacings in the valve springs, vibrations which
cause erratic valve action, are cut down. Wound tightly at top and
bottom, and loosely in the center, the valve spring confines vibrations
to the middle of each spring and imposes a dampening effect from both
ends on even these slight disturbances.
PISTONS
