S.no | Aspects | S.I Engines | C.I Engines |
1
|
Thermodynamics
|
Otto Cyle
|
Diesel Cycle... For slow speed engines
|
2
|
Fuel Used
|
Petrol
|
Diesel.
|
3
|
Air Flow Ratio
|
10:1 to 20:1
|
18:1 to 100:1.
|
4
|
Comparison Ratio
|
Up to 11; Average value 7 to 9;
Upper limit of compression ratio fixed by
anti-knock quality of fuel.
|
12 to 24 ; Average value 15 to 18 ; Upper limit of compression ratio is limited by thermal and mechanical stresses.
|
5
|
Combustion
|
Spark Ignition
|
Compression Ignition.
|
6
|
Fuel Supply
|
By Carburetor...Cheap method
|
By injection.....explosive method.
|
7
|
Operating Pressure
(i)Comparison Pressure
(ii)Maximum Pressure
|
(i)7 bar to 15 bar
(ii)45 bar to 60 bar
|
(i)30 bar to 50 bar (ii) 60 bar to 120 bar
|
8
|
Operating Speed
|
High Speed; 2000 to 6000 rpm
|
Low Speed: 400 rpm.Medium Speed:400 to 1200 rpm.High speed: 1200 to 3500 rpm.
|
9
|
Control Power
|
Quantity Governing... by throttle
|
Quality Governing... by rack.
|
10
|
Calorific Value
|
44 MJ/KG
|
42 MJ/KG
|
11
|
Cost Of Running
|
High
|
Low.
|
12
|
Maintenance Cost
|
Minor Maintenance is required
|
Major Overhaul required but less frequently.
|
13
|
Supercharging
|
Limited by detonation. Used only in Air Craft Engines.
|
Limited by blower power and mechanical and thermal stresses.widely used.
|
14
|
Two Stroke Operation
|
Less Suitable, fuel loss in scavenging.But small two stroke engines are used in mopeds, scooters and motorcycle due to their simplicity and low cost.
|
No fuels loss in scavenging. More suitable.
|
15
|
High Powers
|
No
|
Yes
|
16
|
Uses
|
Mopeds,Scooters,Motorcycle,Simple Engine passenger cars,Air Crafts etc..
|
Buses,Trucks,Locomotives,Tractors,Earth Moving machinery and Stationary Generation Plants
|
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