Engine Types, Firing Order and Operation for SS 3

Class: SS 3
Term: First Term
Week: 2
Age: 14 years
Duration: 45 minutes
Subject: Auto Mechanic Work
Topic: ENGINE – DEFINITION AND TYPES wankel rotary engine.
Subject Matter: We have turbine engine,
Previous Lesson: Routine Chassis Maintenance and Alignment

Specific Objectives

By the end of the lesson, pupils/students should be able to:

Cognitive Domain

• Define an engine.
• List and explain types of engines, specifically gas turbine and Wankel rotary engines.
• Explain the concept of engine firing order.
• Describe the operational sequence of a gas turbine engine.
• Describe the operational sequence of a Wankel rotary engine.

Affective Domain

• Appreciate the importance of understanding different engine types.
• Develop an interest in the mechanics of engine operation.

Psychomotor Domain

• Observe the general layout of an engine on a live vehicle or diagram.
• Illustrate the basic operational cycle of a Wankel or gas turbine engine using diagrams.

Reference Materials

The following resources were used in planning this lesson:

• 2025 Revised 9 Years Basic Education Curriculum
• Relevant State Unified Scheme of Work
• Auto Mechanics for Senior Secondary Schools textbook
• The HeadTeacher Scheme of work

Instructional Materials

The teacher will teach this lesson with the aid of:

• Live vehicle (if available) or an engine model
• Posters illustrating various engine types (e.g., gas turbine, Wankel rotary)
• Charts showing engine components and firing order diagrams
• Diagrams depicting the operational sequence of gas turbine and Wankel engines

Rationale for the Lesson

This lesson is important for students to build foundational knowledge in auto mechanics by understanding what an engine is and its basic classifications. Grasping engine types, firing order, and operational sequences is essential for diagnosing faults and performing maintenance on vehicles, preparing students for practical applications in the field.

Prerequisite/Previous Knowledge

Students should have a basic understanding of mechanical components and the concept of converting energy into motion.

Lesson Content/Board Summary

ENGINE – DEFINITION AND TYPES

Definition of an Engine

An engine is a machine designed to convert one form of energy into mechanical energy. In vehicles, engines typically convert chemical energy from fuel into mechanical power to drive the wheels.

Types of Engines

Engines can be broadly classified based on their operating principles. This lesson focuses on:

1. Gas Turbine Engine: An internal combustion engine that operates by drawing in air, compressing it, mixing it with fuel, igniting the mixture, and using the resulting hot gas to spin a turbine.
2. Wankel Rotary Engine: A type of internal combustion engine that uses a rotor instead of reciprocating pistons to convert pressure into rotating motion.

Engine Firing Order

Firing order refers to the sequence in which the cylinders of a multi-cylinder internal combustion engine ignite their fuel-air mixture. It is designed to ensure smooth operation, balance, and minimize vibrations by distributing power impulses evenly throughout the engine’s rotation.

For example, in a four-cylinder engine, a common firing order might be 1-3-4-2, meaning cylinder 1 fires first, then 3, then 4, and finally 2, before the sequence repeats.

Operational Sequence of Gas Turbine Engines

The operation of a gas turbine engine involves four main stages:

1. Intake: Air is drawn into the engine through an inlet and directed to the compressor.
2. Compression: The compressor increases the pressure and temperature of the air.
3. Combustion: Compressed air is mixed with fuel in the combustion chamber and ignited, creating high-temperature, high-pressure gas.
4. Exhaust/Turbine: The hot gas expands and flows through a turbine, causing it to spin. This rotational energy drives the compressor and can also be used to generate thrust or mechanical power.

Operational Sequence of Wankel Rotary Engines

The Wankel engine operates with a triangular rotor rotating eccentrically within an oval-shaped housing, creating three separate combustion chambers. Its operational sequence involves:

1. Intake: As the rotor turns, a chamber expands, drawing in the fuel-air mixture through an intake port.
2. Compression: Further rotation of the rotor compresses the mixture in the chamber.
3. Combustion/Power: The compressed mixture is ignited by a spark plug, and the expanding gases push the rotor, generating power.
4. Exhaust: As the rotor continues to turn, the chamber contracts, expelling the exhaust gases through an exhaust port.

Teaching Methods/Instructional Techniques

Discussion, Demonstration, Guided Practice, Question and Answer, Explanation, Observation, Visual Aids.

Instructional Procedures

Step 1: Introduction

Time: 5 minutes

Teaching Skill: Recalling/Engaging

Teacher’s Activity: The teacher greets the students and reviews the previous lesson briefly. The teacher then introduces the new topic, “Engine – Definition and Types,” by asking students what they understand by the term ‘engine’ in the context of vehicles.

Pupils’ Activity: Students respond to the teacher’s questions and share their prior knowledge about engines.

Learning Point: Activating prior knowledge

Step 2: Definition of an Engine

Time: 7 minutes

Teaching Skill: Explaining/Defining

Teacher’s Activity: The teacher defines an engine as a machine that converts energy into mechanical work. The teacher uses examples of engines in cars, motorcycles, and airplanes to make the concept concrete.

Pupils’ Activity: Students listen attentively to the definition and examples, asking questions for clarification.

Learning Point: Engine definition

Step 3: Types of Engines (Gas Turbine and Wankel Rotary)

Time: 8 minutes

Teaching Skill: Listing/Explaining

Teacher’s Activity: The teacher lists and briefly explains the two specific engine types for the lesson: gas turbine engines and Wankel rotary engines. The teacher uses posters and charts to show visual representations of these engines.

Pupils’ Activity: Students observe the diagrams, listen to the explanations, and identify the visual differences between the engine types.

Learning Point: Specific engine types

Step 4: Engine Firing Order

Time: 7 minutes

Teaching Skill: Explaining/Illustrating

Teacher’s Activity: The teacher explains the concept of engine firing order, its importance for smooth engine operation, and how it’s determined. If a live vehicle is available, the teacher points out engine cylinders and discusses the concept of sequence.

Pupils’ Activity: Students listen to the explanation, observe any demonstrations, and ask questions about specific firing orders.

Learning Point: Firing order concept

Step 5: Operational Sequence of Gas Turbine Engines

Time: 6 minutes

Teaching Skill: Describing/Visualising

Teacher’s Activity: The teacher describes the four main stages of operation for a gas turbine engine: intake, compression, combustion, and exhaust/turbine. The teacher uses a diagram or chart to illustrate the flow of air and gases through the engine.

Pupils’ Activity: Students follow the explanation on the diagrams and try to visualize the sequence of operations.

Learning Point: Gas turbine operation

Step 6: Operational Sequence of Wankel Rotary Engines

Time: 6 minutes

Teaching Skill: Describing/Comparing

Teacher’s Activity: The teacher explains the unique operational sequence of the Wankel rotary engine, highlighting the role of the rotor and the three chambers. The teacher uses diagrams to show the intake, compression, power, and exhaust phases.

Pupils’ Activity: Students observe the Wankel engine diagrams, compare its operation to other engine concepts they might know, and grasp its unique rotary motion.

Learning Point: Wankel engine operation

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

1. What is an engine?
2. Mention two types of engines discussed today.
3. Explain what is meant by engine firing order.
4. Briefly describe the operational sequence of a gas turbine engine.
5. How does a Wankel rotary engine differ in operation from a conventional piston engine?

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Understanding engine concepts

Step 8: Note-Taking

Time: 4 minutes

Teaching Skill: Guided Writing

Teacher’s Activity: The teacher guides pupils/students to copy the essential Board Summary notes into their notebooks, ensuring they capture the definitions, engine types, firing order, and operational sequences.

Pupils’ Activity: Pupils/students copy the notes carefully into their notebooks.

Learning Point: Recording lesson information

Step 9: Conclusion

Time: 2 minutes

Teaching Skill: Summarizing/Reinforcing

Teacher’s Activity: The teacher briefly summarizes the key points of the lesson, emphasizing the importance of understanding different engine types and their working principles in auto mechanics. The teacher encourages students to observe engines around them.

Pupils’ Activity: Students listen to the summary and prepare for the next lesson.

Learning Point: Lesson consolidation

Continuous Assessment/Further Study

Type: Homework

Instruction: Research and write short notes on the advantages and disadvantages of:

1. Gas turbine engines.
2. Wankel rotary engines.

Lesson Keywords

• Engine – A machine designed to convert energy into mechanical force or motion.
• Gas Turbine Engine – An engine that uses a continuous combustion process to spin a turbine.
• Wankel Rotary Engine – An internal combustion engine that uses a triangular rotor instead of pistons.
• Firing Order – The sequence in which the cylinders of an engine ignite their fuel-air mixture.
• Compression – The process of reducing the volume of a gas, increasing its pressure.
• Combustion – The process of burning fuel to produce heat and expanding gases.

Differentiation

For weaker learners, the teacher will provide simplified diagrams and focus on identifying the main components and basic function of each engine type. Faster learners can be challenged to research and present on other less common engine types or delve deeper into the thermodynamic cycles of gas turbine engines.

Suggested Lesson Videos

For visual demonstrations of engine types and operations, search on YouTube for:

• “How a Gas Turbine Engine Works”
• “Wankel Rotary Engine Explained”
• “Engine Firing Order Explained”

Teacher Guide for Using This Lesson Plan

Before the lesson, ensure all instructional materials, especially diagrams of gas turbine and Wankel engines, are ready and clearly visible. If a live vehicle or engine model is available, plan how to safely demonstrate relevant parts. Begin by engaging students with questions about engines they know. When explaining firing order, emphasize its role in engine balance and smoothness. Guide students through the operational sequences using the visual aids, pointing out each stage clearly. Encourage questions throughout the lesson to check understanding. Students should copy the Board Summary notes after the main teaching points have been covered and evaluated, typically towards the end of the lesson. Provide clear instructions for the homework assignment.