1 | Page
Small engines Questions and Correct Answers/ Latest
Update / Already Graded
What is an engine?
Ans: a device that converts chemical energy into heat energy into mechanical
energy to perform work.
internal combustion engine
Ans: any engine in which fuel is burned within its body
small internal combustion engine
Ans: small-size
internal- power produced in a chamber
combustion- ignition and burning of the fuel/air mixture
engine- makes power independently
History
Ans: internal combustion engines were invented in the 17th century.
Primitive designs used fuels such as coal dust and gunpowder.
Automobiles used gasoline powered engines int he early 1900s.
Partnerships in 1920s made a small engine leader in the industry- that was Harry
Stratton and Steve Briggs
The first automobiles
Ans: the horseless carriage.
How internal combustion engines work
© 2025/ 2026 | ® All rights reserved
, 2 | Page
Ans: the combustion that occurs within the cylinder produces energy which
moves the parts of the engine that drive equipment.
Engines can be classified by
Ans: type of ignition
number of strokes per cycle
cylinder design
shaft orientation
cooling system design
ignition systems
Ans: type of system is determined by how the fuel is ignited.
Spark ignition- air/fuel mixture is ignited with an electrical spark (ex. gasoline)
compression ignition- fuel ignites from compression produced in the engine cycle
(ex. diesel)
both type of systems can be found on 2 and 4 stroke engines
number of strokes
Ans: engines are classified as either 2 or 4 stroke cycle.
-when the piston is at the highest point int he cylinder, it is in a position called top
dead center (TDC)
- when the piston is at its lowest point in the cylinder, it is in a position called
bottom dead center (BDC)
-each movement of the piston from top to bottom or from bottom to top is
called a stroke
- therefore, the piston completes two strokes from every full crankshaft rotation.
In a 4-stroke engine, the piston makes 4 separate strokes to complete one cycle
In a 2-stroke engine, the piston makes 2 separate strokes to complete one cycle
cylinder design
© 2025/ 2026 | ® All rights reserved
, 3 | Page
Ans: small engines typically are <_ 31 HP and have 1-4 cylinders
cylinder orientations:
- vertical
-horizontal
- slanted
cylinder orientation/configuration is selected for power and application
requirements:
-2 cylinder V engines- 2 cylinder power in a compact space
-horizontal opposed- low profile with low vibration
-in-line, vertical and horizontal engines require more space w/ multiple cylinders
shaft orientation
Ans: axis of the crankshaft
-vertical
-horizontal
Orientation is selected for efficiency of auxiliary driven components
ex. walk behind mower
cooling system
Ans: when fuel is ignited in a typical small engine, ~30% of energy produced is
converted to useful work.
Remaining energy is lost:
-heat to cooling air
- exhaust system
- radiation
-friction
types of cooling systems
© 2025/ 2026 | ® All rights reserved
Small engines Questions and Correct Answers/ Latest
Update / Already Graded
What is an engine?
Ans: a device that converts chemical energy into heat energy into mechanical
energy to perform work.
internal combustion engine
Ans: any engine in which fuel is burned within its body
small internal combustion engine
Ans: small-size
internal- power produced in a chamber
combustion- ignition and burning of the fuel/air mixture
engine- makes power independently
History
Ans: internal combustion engines were invented in the 17th century.
Primitive designs used fuels such as coal dust and gunpowder.
Automobiles used gasoline powered engines int he early 1900s.
Partnerships in 1920s made a small engine leader in the industry- that was Harry
Stratton and Steve Briggs
The first automobiles
Ans: the horseless carriage.
How internal combustion engines work
© 2025/ 2026 | ® All rights reserved
, 2 | Page
Ans: the combustion that occurs within the cylinder produces energy which
moves the parts of the engine that drive equipment.
Engines can be classified by
Ans: type of ignition
number of strokes per cycle
cylinder design
shaft orientation
cooling system design
ignition systems
Ans: type of system is determined by how the fuel is ignited.
Spark ignition- air/fuel mixture is ignited with an electrical spark (ex. gasoline)
compression ignition- fuel ignites from compression produced in the engine cycle
(ex. diesel)
both type of systems can be found on 2 and 4 stroke engines
number of strokes
Ans: engines are classified as either 2 or 4 stroke cycle.
-when the piston is at the highest point int he cylinder, it is in a position called top
dead center (TDC)
- when the piston is at its lowest point in the cylinder, it is in a position called
bottom dead center (BDC)
-each movement of the piston from top to bottom or from bottom to top is
called a stroke
- therefore, the piston completes two strokes from every full crankshaft rotation.
In a 4-stroke engine, the piston makes 4 separate strokes to complete one cycle
In a 2-stroke engine, the piston makes 2 separate strokes to complete one cycle
cylinder design
© 2025/ 2026 | ® All rights reserved
, 3 | Page
Ans: small engines typically are <_ 31 HP and have 1-4 cylinders
cylinder orientations:
- vertical
-horizontal
- slanted
cylinder orientation/configuration is selected for power and application
requirements:
-2 cylinder V engines- 2 cylinder power in a compact space
-horizontal opposed- low profile with low vibration
-in-line, vertical and horizontal engines require more space w/ multiple cylinders
shaft orientation
Ans: axis of the crankshaft
-vertical
-horizontal
Orientation is selected for efficiency of auxiliary driven components
ex. walk behind mower
cooling system
Ans: when fuel is ignited in a typical small engine, ~30% of energy produced is
converted to useful work.
Remaining energy is lost:
-heat to cooling air
- exhaust system
- radiation
-friction
types of cooling systems
© 2025/ 2026 | ® All rights reserved
