T
RAINING
M
ANUAL
–
L
ANCAIR
IV/IVP
Turbochargers compress air in the intake to the cylinder by using exhaust gases
from an engine-driven turbine wheel to drive a compressor. The increased air
density provides greater power and improved performance. The turbocharger
system allows the engine to develop higher than sea level pressure (up to 38.5
inches of manifold pressure) up to a critical altitude. To operate at altitudes
below the critical altitude an automatic waste gate is installed in the
turbocompressor to release unnecessary gas pressure. The waste gate is a
damper-like device that controls the amount of exhaust that strikes the turbine
rotor. As the waste gate closes with altitude, it sends more gases through the
turbine compressor, causing the rotor to spin faster. This allows the engine to
function as if it were maintaining sea level or, in the case of a supercharger,
above sea level manifold pressure.
Automatic Waste Gate
Automatic waste gates operate on internal pressure. When internal pressure
builds towards an overboost, the waste gate opens to relieve pressure, keeping
the engine within normal operating limits regardless of the air density.
(a) The pressure-reference automatic waste gate system maintains the
manifold pressure set b the throttle. Engine oil pressure moves the
waste gate to maintain the appropriate manifold pressure, thus
reducing the pilot’s workload and eliminating the possibility of
overboost. If the airplane engine is started up and followed by an
immediate takeoff, cold oil may cause a higher than intended manifold
pressure. Allow the oil to warm up and circulate throughout the system
before takeoff.
‐
59
–
©
Copyright
2007
LOBO
May
not
be
copied
without
permission.