Auto../Repair../Technician../Lesson../1
When../the../bore../is../larger../than../the../stroke,../the../engine../is../_____.
a.)../even.
b.)../oversquared.
c.)../free../wheeling.
d.)../undersquared.../-../correct../answer../oversquared../-
../The../space../between../the../piston../and../the../cylinder../head../when../the../piston../i
s../at../TDC../is../the../clearance../space.../It's../sometimes../called../the../compression.
./or../combustion../space.../The../volume../of../this../space../is../known../as../the../cleara
nce../volume.../When../the../bore../is../larger../than../the../stroke,../the../engine../is../ove
rsquared,../and../most../of../its../power../is../dependent../upon../revolutions../per../min
ute../(rpm)../and../generated../at../higher../rpm../values.../When../the../stroke../is../larg
er../than../the../bore,../the../engine../is../undersquared,../with../most../of../its../power../d
ependent../upon../torque.
Which../stroke../of../the../four-stroke../cycle../is../shown../in../the../above../figure?
a.)../Intake
b.)../Exhaust
c.)../Compression
d.)../Power../-../correct../answer../Exhaust../-
../Stage../1:../During../the../intake../stage,../air../that../has../been../mixed../with../fuel../is../
drawn../into../the../cylinder.
, Stage../2:../During../the../compression../stage,../the../piston../rises../and../compresse
s../the../air-and-fuel../mixture../that's../trapped../in../the../combustion../chamber.
Stage../3:../During../the../power../stage,../the../air-and-
fuel../mixture../is../ignited../by../a../spark,../and../the../contained../explosion../of../the../f
uel../presses../the../piston../back../down../in../the../cylinder.../The../downward../moti
on../of../the../piston../is../transferred../to../the../rod../and../crankshaft.
Stage../4:../During../the../exhaust../stage,../the../burned../exhaust../gases../are../releas
ed../from../the../cylinder.../During../the../exhaust../stroke,../the../piston../rises../and../th
e../exhaust../valve../opens.../The../rising../piston../pushes../the../remaining../burned../
gases../in../the../cylinder../out../through../the../open../exhaust../valve.
Technician../A../says../that../horsepower../is../defined../as../work../per../unit../of../time.
./or../the../rate../of../doing../work.../Technician../B../says../that../one../horsepower../equ
als../550../foot-pounds../per../seconds.../Who../is../right?
a.)../B../only
b.)../Both../A../and../B
c.)../Neither../A../nor../B
d.)../A../only../-../correct../answer../Both../A../and../B../-
../Horsepower../is../defined../as../work../per../unit../of../time.../It's../the../rate../of../doing../
work../or../torque../and../is../the../unit../of../measurement../that../expresses../the../pow
er../output../of../an../internal../combustion../engine.
1../horsepower../=../550../foot-pounds../per../second
When../the../bore../is../larger../than../the../stroke,../the../engine../is../_____.
a.)../even.
b.)../oversquared.
c.)../free../wheeling.
d.)../undersquared.../-../correct../answer../oversquared../-
../The../space../between../the../piston../and../the../cylinder../head../when../the../piston../i
s../at../TDC../is../the../clearance../space.../It's../sometimes../called../the../compression.
./or../combustion../space.../The../volume../of../this../space../is../known../as../the../cleara
nce../volume.../When../the../bore../is../larger../than../the../stroke,../the../engine../is../ove
rsquared,../and../most../of../its../power../is../dependent../upon../revolutions../per../min
ute../(rpm)../and../generated../at../higher../rpm../values.../When../the../stroke../is../larg
er../than../the../bore,../the../engine../is../undersquared,../with../most../of../its../power../d
ependent../upon../torque.
Which../stroke../of../the../four-stroke../cycle../is../shown../in../the../above../figure?
a.)../Intake
b.)../Exhaust
c.)../Compression
d.)../Power../-../correct../answer../Exhaust../-
../Stage../1:../During../the../intake../stage,../air../that../has../been../mixed../with../fuel../is../
drawn../into../the../cylinder.
, Stage../2:../During../the../compression../stage,../the../piston../rises../and../compresse
s../the../air-and-fuel../mixture../that's../trapped../in../the../combustion../chamber.
Stage../3:../During../the../power../stage,../the../air-and-
fuel../mixture../is../ignited../by../a../spark,../and../the../contained../explosion../of../the../f
uel../presses../the../piston../back../down../in../the../cylinder.../The../downward../moti
on../of../the../piston../is../transferred../to../the../rod../and../crankshaft.
Stage../4:../During../the../exhaust../stage,../the../burned../exhaust../gases../are../releas
ed../from../the../cylinder.../During../the../exhaust../stroke,../the../piston../rises../and../th
e../exhaust../valve../opens.../The../rising../piston../pushes../the../remaining../burned../
gases../in../the../cylinder../out../through../the../open../exhaust../valve.
Technician../A../says../that../horsepower../is../defined../as../work../per../unit../of../time.
./or../the../rate../of../doing../work.../Technician../B../says../that../one../horsepower../equ
als../550../foot-pounds../per../seconds.../Who../is../right?
a.)../B../only
b.)../Both../A../and../B
c.)../Neither../A../nor../B
d.)../A../only../-../correct../answer../Both../A../and../B../-
../Horsepower../is../defined../as../work../per../unit../of../time.../It's../the../rate../of../doing../
work../or../torque../and../is../the../unit../of../measurement../that../expresses../the../pow
er../output../of../an../internal../combustion../engine.
1../horsepower../=../550../foot-pounds../per../second
