Turbo charger Flashcards
Basic function of a turbo
utilizes exhaust gases and heat to drive a centrifugal air pump that increases air pressure of the air entering the intake manifold
five other things a turbo can do for and engine
helps operate at higher altitude
increase power without adding weight
increases power without needing larger engine
compensates for varying load demands
reduced exhaust gas and increases fuel economy
after cooler and intercoolers are used with turbo because
as air is compressed it heats up becoming less dense hot air must be cooled to get the best benefit from the increased air flow
as a result of the increased air flow to the cylinders
you will get increased turbulence as well aiding in the combustion process
difference of turbo over naturally aspirated
compression ratio is lower
cam and valve timing are changed to fully gain the benefits
injection timing is retarded
fuel injection pump out put or fuel injector size is increased
centrifugal fuel injection advance may not be required
crankcase vent could be vented to atmosphere
power out put of a turbo charged engine
may be as much as 50% more
turbocharger is often called a
centrifugal air pump
a turbo charger operates in direct proportion to engine speed true or false
false
as the amount of engine exhaust heats up the turbo speed will also increases
turbocharger components include
turbine housing , turbine wheel , compressor housing , compressor wheel
turbine housing
used to direct hot expanding exhaust gases to the turbine wheel causing the turbine shaft to rotate
due to high temps on the exhaust tide housing must be heat resistant usually made from cast
nozzle constructed of a series of veins is for
directing the flow of exhaust gas to the outer edge of the turbine wheel so it will receives constant force
wastegates are used for
diverting some of the exhaust gas from the turbine wheel to help maintain safe intake manifold pressure
compressor housing usually constructed out of
aluminium due to the lower heat on the intake side
diffuser plate used on the compressor side used for
helps direct the boost air to the intake manifold
why must the turbo charger get full oil flow right away
because when the engine starts up the turbo can reach high speeds soon after
how do some turbochargers stop internal oil from pushing past the seals during normal operation
with a wind back seal
why are piston rings used to seal turbo oil cavity
because of the high operating temps
why must radial and axial movements be kept with in spec
because the turbine or compressor wheels may come into contact with the housing
what must you do after running an engine with a turbo under loaded conditions
allow time for the turbo to cool down with system oil before shut down
a turbo that is cooled to fast may warp crack or have premature bearing failure
blue smoke from an engines exhaust
engine is likely burning oil
could be from worn piston rings or oil might be leaking into the compressor side of the turbo and feeding the engine
if the oil drain on the turbo was plugged
oil into the turbo could become pressurized and leak past the seals into the turbine or compressor housing
what is an important step to take when installing a new turbo
pre fill the turbo with oil and spin by hand to ensure it will have proper lubrication before start up
shut down procedure for turbo
run at half speed for 3 to 5 min
then idle for another 3 to 5 min
this allows engine oil to remove as much heat as possible before shut down
why must you cover turbo exhaust during transport
because air flow over exhaust turbine could cause the intake side to turn and premature bearing wear could ensue
where is the after cooler or intercooler usually located
after the turbo and before the cylinders
air to air coolers can reduce the heat of incoming air from
135 to 160 down to 43 degrees
why is an air to air more effective in cooling then a air to coolant
because the ambient temperature of the air moving through a air to air cooler is much lower then the temp of the coolant in the air to coolant system
one clue to coolant in the intake manifold
white smoke out the exhaust
why are waste gates and variable displacement turbochargers used
to control the amount of exhaust acting on the turbine to affect haw much boost or turbine speed you can have under various loads
waste gate function
senses the amount of boost pressure in the system and allows a specific value of exhaust gas to bypass the turbine controlling your maximum boost
two types of VDT
pivoting nozzle vain
sliding nozzle vain
Sliding nozzle vain operation
air actuated linkage controls the sliding nozzle back and forth controlling the amount of backpressure acting on the turbo
pivoting nozzle vain operation
air actuated vain open and close to controll the amount of exhaust gas back pressure acting on the turbine
