Lesson 4

Learning objectives:

Within the lesson, the students are expected to:

a. Distinguish the differences between 4-Stroke and 2-Stroke Engine.

b. Illustrate the similarities and differences of 4-stroke and 2-stroke engine through a Venn Diagram.

c. Manifest what they have learned about 4-Stroke and 2-Stroke Engine through a summary report

Subject Matter

Topic: 4 Stroke Vs. 2 Stroke Engine

Materials

Skills: Reports and Media

Mode of Delivery: Online class using Google Meet

Time Allotment: 2days/ 180 minutes (one week)

High Technology: short video clips, online teaching platforms (Google Form)

reference:

https://www.berrymanproducts.com/two-stroke-vs-four-stroke-engines/

https://www.ganshoren.be/nl/contact/?w=5.3.1259920.4.29.87.2+stroke+cycle

https://youtu.be/LuCUmQ9FxMU

https://youtu.be/Pu7g3uIG6Zo

https://www.autowizsec.com/post/4-stroke-engine-and-its-working

A. Pre-Activity

1. Prayer

2. Checking of Attendance

3. Review

4. Setting of Standards

Activity 1:

• The teacher will ask the following questions to the class.

1. What comes to your mind when you see this image?

2. What steps do you undergo before using a vehicle?

3. Do you think it is important to know the process happening inside your vehicle? Why?

B. Lesson proper

• Discussion will be done on google meet

Instructions:

• The students must follow the instructions presented by the teacher.

• The Students must answer the provided quiz after the lectures for extra points.

• The link is provided below.

How Do Combustion Engines Work, and What Is A “Stroke” Anyways?

In order to understand how these two engines are different, you first need to become familiar with the basics.

During an engine’s combustion cycle, the piston moves up and down within the cylinder. The terms “top dead center” (TDC) and “bottom dead center” (BDC) refer to the piston’s position within the cylinder. TDC is its position nearest to the valves, and BDC is its position furthest from them. A stroke is when the piston moves from TDC to BDC, or vice versa. A combustion revolution or combustion cycle is the complete process of gas and air being sucked into the piston, igniting it, and expelling the exhaust:

• Intake: The piston moves down the cylinder allowing a mixture of furl and air into the combustion chamber

• Compression: The piston moves back up the cylinder; the intake valve is closed to compress the gasses within

• Combustion: A spark from the spark plug ignites the gas

• Exhaust: The piston goes back up the cylinder and the exhaust valve is opened

Difference Between A 2-Stroke & A 4-Stroke

The Difference between a 2-stroke and a 4-stroke engine is how quickly this combustion cycle process occurs, based on the number of times the piston moves up and down during each cycle.

4-Stroke:

In a 4-stroke engine, the piston completes 2-strokes during each revolution: one compression stroke and one exhaust stroke, each being followed by a return stroke. The spark plugs fire only once every other revolution, and power is produced every 4-strokes of the piston. These engines also do not require pre-mixing of fuel and oil, as they have a separate compartment for the oil.

Pro’s and Con’s:

So, which is ‘better’? Here are a few of the pro’s and con’s to both engine designs:

• As far as efficiency goes, the 4-stroke certainly wins. This is due to the fact that fuel is consumed once every 4 strokes.

• Four-stroke engines are heavier; they weigh upwards of 50% more than a comparable 2stroke engine.

• Typically, a 2-stroke engine creates more torque at a higher RPM, while a 4-stroke engine creates a higher torque at a lower RPM.

• The 4-stroke engine is also much quieter, a 2-stoke engine is significantly louder and has a distinctive, high-pitched “buzzing” sound.

• Because 2-stroke engines are designed to run at a higher RPM, they also tend to wear out faster; a 4-stroke engine is generally more durable. That being said, 2-stroke engines are more powerful.

• Two-stroke engines are a much simpler design, making them easier to fix. They do not have valves, but rather ports. Four-stroke engines have more parts, therefore they are more expensive and repairs cost more.

• Two-stroke engines require pre-mixing of oil and fuel, while the 4-strokes do not.

• Four-strokes are more environmentally friendly; in a 2-stroke engine, burnt oil is also released into the air with the exhaust.

Two-stroke engines are typically found in smaller applications such as remote-controlled cars, lawn tools, chainsaws, boat motors and dirt bikes. Four-stroke engines are found in anything from go-karts, lawnmowers and dirt bikes, right up to the typical internal combustion engine in your vehicle. It’s up to you to decide which engine you prefer, and for what purpose.

Activity 2: Do It!

• Illustrate the similarities and differences of 4-stroke and 2-stroke engine through a Venn Diagram.

D. Generalization

• The teacher will ask someone to wrap up the lessons

VI. Assignment

Instructions:

• Find a tool or equipment in your home that can be used in repairing or maintaining a vehicle or any vehicle related to our topic.

• Record yourself showing the tools and their function and explain their significance.

• Upload your work in the button below.