Four-Stroke Engine Basics

Objectives:

• After the completion of this power point, the student will understand:
• What a four-stroke engine is,
• Other engine types,
• Basic components of a four-stroke engine,
• The four-stroke cycle.

The Basics

• A four-stroke engine:
• Is an internal combustion engine,
• Converts gasoline into motion,
• Is the most common car engine type,
• Is relatively efficient,
• Is relatively inexpensive.

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Other Engine Types

• Two-stroke engines
• Diesel engines
• Rotary engines
• Turbine engines
• Steam engines

Basic Components of Four-Stroke Engines

Intake Valve

Valve Cover

Intake Port

Head

Coolant

Engine Block

Oil Pan

Oil Sump

Crankshaft

Camshaft

Exhaust Valve

Spark Plug

Exhaust Port

Piston

Connecting Rod

Rod Bearings

Next Diagram

A. Intake Valve

• Opens at the proper time to let in air and fuel. Larger than the exhaust valve.

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B. Valve cover

• Protects the valves and the valve springs. Keeps dirt out and lubricating oil in.

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C. Intake Port

• The passageway in a cylinder head for the fuel and air to pass through.

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C. Head

• A platform containing most of the parts of the combustion chamber.

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E. Coolant

• Circulating water and antifreeze to keep the temperature regulated.

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F. Engine Block

• Cast in one piece. The basis for most of the parts of the engine.

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G. Oil Pan

• Where the oil is collected and recirculated.

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H. Oil Sump

• The collected oil primarily for lubricating the crankshaft and rod bearing

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I. Camshaft

• A round shaft with lobes, that rotates to open and close the fuel and exhaust valves.

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J. Exhaust Valve

• Opens at the proper time to release the exhaust.

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K. Spark Plug

• A device inserted into the combustion chamber for firing an electrical spark to ignite air-fuel mixture

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L. Exhaust Port

• The passageway in a cylinder head for the exhaust to pass through

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M. Piston

• The part of the engine that moves up and down in the cylinder converting the gasoline into motion

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N. Connecting Rod

• Links the piston to the crankshaft.

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O. Rod Bearing

• Used to reduce friction to the rod and crankshaft

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P. Crankshaft

• Converts the up and down motion of the piston into a turning, or rotating motion

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The 4-Stroke Cycle

• 1.
• 2.
• 3.
• 4.

Intake

Compression

Combustion

Exhaust

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The Intake Stroke

• The process of filling the cylinder with the proper air-fuel mixture through the intake valve.

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The Compression Stroke

• Compression- The process of compressing the air-fuel mixture in the cylinder to make it more combustible.

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The Combustion Stroke

• Combustion-the process of igniting the compressed air-fuel mixture to create motion and the overall power of the engine.
• Also known as the power stroke.

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The Exhaust Stroke

• The process of releasing the exhaust out of the cylinder through the exhaust valve.
• Prepares chamber for the next charge.

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Application

• Now that you understand the basics of four-stroke engines, how can you use this information in the real world?

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Quiz

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• Lets take a quiz to see what you have learned!

Question #1

The ____ controls the amount of intake and the release of exhaust.

a. head

b. valves

c. coolant

d. connecting rod

Question #2

The _____ Cycle is the ignition of the compressed fuel-air mixture.

a. Exhaust

b. Combustion

c. Intake

d. Compression

Question #3

The most common type of engine?

a. diesel engines

b. 2-stroke engines

c. rotary engines

d. 4-stroke engines

Question #4

What part of the engine converts up and down motion into a rotation motion?

a. crankshaft

b. piston

c. valve cover

d. camshaft

Question #5

What is the name of the part listed?

a. intake valve

b. piston

c. oil pan

d. spark plug

Next

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Next

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Congratulations!

• That is the end of your quiz, and the end of your lesson on four-stroke engines.

References

• www.howstuffworks.com/

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• �Roth, Alfred C. Small Gas Enginges:

Funamental, Service, Troubleshooting, Repair, and Application. 10th. Tinely Park, Illinois: Goodheart-Willcox Company, Inc., 2012. Print.

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