Piper SARATOGA PA-32-301 Maintenance Manual page 593

PIPER AIRCRAFT
PA-32-301/301T
MAINTENANCE MANUAL
TURBOCHARGER NOMENCLATURE.
Many unfamiliar terms may appear on the following pages of this manual. An understanding of these will
be helpful. if not necessary, in performing maintenance and troubleshooting. The following is a list of
commonly used terms and names as applied to turbocharging.
TERM
MEANING
Supercharge
Supercharger
Turbo-supercharger
Compressor
Turbine
Wastegate
To increase the air pressure (density) above or higher than ambient conditions.
A device that accomplishes the increase in pressure.
More commonly referred to as a "Turbocharger" this device is driven by a
turbine. The turbine is spun by energy extracted from the engine exhaust gas.
The portion of a turbocharger that takes in ambient air and compresses it
before discharging it to the engine.
The exhaust driven end of the turbocharger unit.
The wastegate is a butterfly type valve in the exhaust by-pass which.
throughout its travel from open to closed, allows varied amounts of exhaust
pressure to by-pass the turbine, controlling its speed. hence the output of the
compression.
Ground Boosted or
Ground Turbocharged
These phrases indicate that the engine depends on a certain amount of
turbocharging at sea level to produce the advertised horsepower. An engine
that is so designed will usually include a lower compression ratio to avoid
detonation.
Deck Pressure
Manifold Pressure
Normalizing
Overboost
The pressure measured in the area downstream of the turbo compressor
discharge and upstream of the engine throttle valve. This should not be
confused with manifold pressure.
The pressure measured downstream of the engine throttle valve and is almost
directly proportioned to the engine power output.
If a turbocharger system is used only to regain power losses caused by
decreased air pressure of high altitude, it is considered that the engine has been
"normalized."
An overboost condition means that manifold pressure is exceeding the limits at
which the engine was tested and FAA certified and can be detrimental to the
life and performance of the engine. Overboost can be caused by
malfunctioning controllers or improperly operating wastegate in the
automatic system or by pilot error in a manual controlled system.
81-00-03
Page 81-06
Issued: January 2, 1980
3B16