This lab involves studying the effect of compression ratio on engine performance and power for both spark ignition and compression ignition engines. Students will plot torque, power and performance curves at different speeds for varying compression ratios. The dual engine test bench allows students to examine both gasoline and diesel engines. Key components like the spark plug, ignition distributor and carburetor are used in spark ignition mode, while the diesel injector, high pressure fuel lines and pump are used in compression ignition mode. Charts of compression ratio and the engine components are provided.

1. LAB 6: Study the effect of the compression ratio on the
performance and power of an engine (CI&SI), be able to
plot the torque, power and performance curves in
function of the speed for different values of the
compression ratio.
ME-469L (IC Engines and Power Plants Lab)
Umair Munir
Lab Engineer

2. Water-Cooled Dual Engine [TM12-01]
Engine Specifications
Type of engine Spark ignition/
compression ignition
Maximum power 5.8 kW/1800 rpm CR 18:1
5.7 kW/1800 rpm CR8:1
Fuel Petrol/Diesel Maximum torque 30 N.m
No. of cylinders 1 Type of air intake Naturally aspired
No. of strokes 4 Type of cooling Water
Cylinder bore 87.5 mm Starter Electric
Cylinder stroke 110 mm Compression ratio Variable
2

3. Study of the effect of the compression ratio on
the performance and power of an engine
• What is Compression Ratio?
Compression ratio is defined as the
ratio between total cylinder volumes
to clearance volume. The higher this
ratio, the greater will be the power
output from a given engine.
3

4. 4
General Description of Single Cylinder
Water Cooled Dual Engine [TM12-01]

5. 5
1. Engine block
2. Cylinder head
3. Electric starter motor
4. Coupling to the starter motor
5. Emergency stop pushbutton in
petrol mode
6. Inertia flywheel
7. Cooling water inlet to the engine
8. ST-7, temperature sensor for the
cooling water inlet
9. Valve to open the cooling water
inlet
10. Decompression lever
11. Compression ratio variator
17. Dipstick to measure the oil level
18. Case venting system

6. 6
12. Cooling water outlet
from the engine
13. ST-6, temperature
sensor for the cooling water
outlet
14. Duct for the engine
exhaust gases
15. Damping supports
16. ST-4, oil temperature
sensor

7. Compression Ratio for Petrol & Diesel 7

8. Engine working in SI
mode 8
1. Spark plug
A spark plug is a device for delivering electric current
from an ignition system to the combustion chamber of a
spark-ignition engine to ignite the compressed fuel/air
mixture by an electric spark, while containing
combustion pressure within the engine.
2. Ignition distributor
A distributor is an enclosed rotating switch used in spark-
ignition internal combustion engines that have
mechanically timed ignition. The distributor's main
function is to route high voltage current from the
ignition coil to the spark plugs in the correct firing order,
and for the correct amount of time.

9. 9
Engine working in SI mode
3. Carburetor
A carburetor or carburettor is a
device that mixes air and fuel for
internal combustion engines in an
appropriate air–fuel ratio for
combustion.
4. Cable of the accelerator
5. Passage valve for the petrol

10. 10
Engine working in CI
mode
1. Diesel oil injector
2. Diesel oil high pressure duct
3. Return from the injector to the
filter

11. 11
Engine working in CI mode
2. Diesel oil high pressure duct
3. Return from the injector to the
filter
4. Diesel oil pump
5. Diesel oil filter
6. Diesel oil pump suction duct
7. Duct for the inlet of diesel oil
into the filter
8. Duct for the inlet of air to the
engine

12. 12
Compression
Ratio Chart

13. Lab Manual 13

14. Questions 14

15. 15