Chassis Information --- Section 10
The Executive 2005
471
ENGINE - GENERAL INFORMATION
The diesel engine operates differently from the conventional gasoline engine. Gasoline engines con-
trol engine speed using a butterfly throttle plate controlling air/fuel mixture inlet flow. As the throttle
plate opens, vacuum created by the piston velocity draws the metered fuel/air charge into the com-
bustion chamber, then ignites from a controlled electric ignition source. Closing the throttle plate limits
the fuel/air supply, slowing engine speed, increasing intake manifold vacuum.
The diesel engine in the motorhome controls engine speed by varying fuel supply only. No
throttle plates are used. An exhaust driven turbine system (turbocharger) compresses the fresh air
supply into the engine. The fuel is injected under pressure into the combustion chamber. Ignition of
fuel/air charge occurs from heat generated by rapid high compression. The turbo boost gauge registers
amount of intake manifold pressure measured in lbs./in². Therefore, no intake manifold vacuum exists.
Diesel engine RPM (revolutions per minute) operating speeds are generally much lower than that of
the gasoline engine. Peak torque and horsepower output values occur at much lower engine speeds.
Idle speeds between the two engine types are similar, however maximum engine speeds are quite
different. The gasoline engine generally is not regulated to a maximum engine speed. The maxi-
mum engine speed on a diesel engine is controlled by an engine speed governor set by the engine
manufacturer.
WARNING:
Do not operate a diesel engine where there are or can be combustible vapors.
Vapors can be drawn through the air intake system and cause engine acceleration
and over-speeding, resulting in fire, explosion and extensive property damage.
Numerous safety devices are available, such as air intake shutoff devices, to mini-
mize risk of an engine over-speeding where an engine (due to its application)
might operate in a combustible environment, such as fuel spills or gas leaks.
INFORMA
TION:
It is the responsibly of the owner to operate the engine in a safe manner. Consult
the engine manufacturers owners manual for detailed operating and maintenance
instructions.
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