This document provides an overview of four-stroke and two-stroke engines. It describes the four strokes of a four-stroke engine: intake, compression, power, and exhaust. It also outlines the two strokes of a two-stroke engine: the intake/combustion stroke and the expansion/exhaust stroke. The document compares key aspects of four-stroke and two-stroke engines such as the number of rotations required to complete a cycle, how power is produced, and design complexity. It provides details on the function and timing of valves and ports during each stroke.

1. Presentation on Four stroke and Two Stroke
Engine
Muhammad Awais
BSMT-F17-LC-007
Prepared by
Azmeer CH
BSMT-F17-LC-008
Department of Mechanical
University of Sargodha Lahore Campus

2. Engine

3. Classification of Engine
IC
Internal combustion
EC
External Combustion

4. Type of fuel
 Petrol
 Diesel
 Gas
 Bio and alternative fuel

5. Number of strokes
 Two stroke Petrol
 Two-Stroke Diesel
 Four Stroke Petrol
 Four Stroke Diesel

6. Parts of Engine
Engine head Engine block
Crank shaft
Connecting Rod

7. Parts of Engine
Came Shaft Engine Valve
Spark Plug Piston Rings

8. Full Diagram

9. Four Stroke Engine
There are mainly four storks in 4-stork engine
 Suction/Intake Stroke
 Compression Stroke
 Power Stroke
 Exhaust Stroke

10. Suction/Intake Stroke
 inlet valve opens
 exhaust valve closed
 the pressure in the cylinder will
be atmosphere
 the piston moves from the TDC
To BDC
 the volume in the cylinder
increase
 180 degree of crank angle

11. Compression Stroke
 inlet valve and exhaust valve
are closed
 The piston moves from BDC
to TDC
 The charge contained in the
cylinder will be compressed
 Pressure and temperature of
charge increases

12. Power Stroke
 The inlet valve and exhaust valve
are closed
 The piston moves from TDC to
BDC
 The engine produces mechanical
work or power
 The pressure of hot gases
gradually decreases and volume
increases

13. Exhaust Stroke
 The exhaust valve opens and
the inlet valve is closed
 The piston moves from BDC
to TDC
 During this motion piston
pushes the exhaust gases
 Again the inlet valve open
and the new cycle starts

14. Two Stroke Engine

15. INTRODUCTION
 In 1878, Dugald-clerk, a British engineer introduced a
cycle
 which could be completed in two stroke of piston rather
than four strokes as is the case with the four stroke cycle
engines. the engines using this cycle were called two
stroke cycle engines
 In this engine suction and exhaust strokes are eliminated
 Here, instead of valves, ports are used. The exhaust gases
are driven out from cylinder by the fresh charge of fuel
entering the cylinder nearly at the end of the working
stroke.

16. Identify 2 stroke engine from outside
 Exhaust port in center of cylinder
 Small crankcase

17. Two Stroke Engine
There are mainly two storks in 2 stork engine
 Suction stroke
 Compression stroke
 Expansion stroke
 Exhaust Stroke
One half cycle of the crank shaft for one stroke in
two stroke engine

18. Strokes name
 First stroke (intake +combustion)
 Second one is (expansion +exhaust)

19. First Stroke
 The piston is moved from
TDC to BDC
 Exhaust and transfer port
open and inlet port close
 Piston movedTDC to BDC
and burnt gasses exhaust
 Crank Shaft rotate 180
degree

21. Second Stroke
 Piston moved from BDC to
TDC and compressed fuel
and burn it
 Exhaust and transfer port
close and inlet port open
 Crank shaft complete 360
degree and complete 2 stroke
and 4 process

22. Compression
4 Stroke Engine 2 Stroke Engine
 4 stroke engine completes 2
rotations of crankshaft after
completing one cycle.
 Power is produced once every
4 strokes of the piston.
 Engine design is a bit
complicated due to valve
mechanism.
 2 stroke engine completes 1
rotation of crankshaft after
completing one cycle.
 Power is produced once
during 2 strokes of the piston.
 2 stroke engine has ports
which makes it's design
simpler.

23. Compression
 No need of adding oil or
lubricant to fuel.
 Top side of the piston is
flat.
 Mixture remains only in
the combustion
chamber.
 4 stroke engines are
heavier.
 4 stroke engines make
less noise.
 Addition of oil is
required.
 A bump or protuberance
may be needed on top
side of piston.
 Air-fuel mixture enters
through inlet port &
travels to combustion
chamber
 2 stroke engines are
lighter
 2 stroke engines are
louder comparatively.