It is common for a non-technical person to get confuse between a diesel and a petrol engine mostly in terms of their technicality and uses. In this article, a non-technical person will easily understand the difference between the two engines.
An internal combustion engine operates either in two strokes or four strokes. In simple terms, we can say that in two strokes every revolution of the crankshaft has a power stroke and in four strokes, there is one power stroke for every two revolutions of the crankshaft.
What is an SI Engine?
SI engine uses a spark plug to initiate combustion in the combustion chamber. There is a carburetor in the SI engine which sucks the air from outside and mixes it with the fuel. As air fuel mixture is injected in the combustion chamber and spark plug provides a spark. It uses petrol as the working fluid.The air-fuel mixture ratio is provided and controlled by the carburetor. The compression ratio is lower and lies between 10:1 and 14:1. Its efficiency lies between 20% and 35%. Due to presence of the spark plug in the SI engines, it easily starts during winters. Moreover, it has low vibration and low noise production. The cylinder block is also lightweight and maintenance cost is lower than a diesel Engine.
What is a CI Engine?
Compression-Ignition (CI) engine is also known as the Diesel engine.It is also an internal combustion engine like the SI engine which uses fuel and air for combustion. Contrarily to the SI engine, in the CI engine, there is no spark plug.The combustion is initiated by increasing the temperature of the air inside the chamber. A diesel engine is built robustly to withstand high temperature and high compression ratio, therefore they have more weight than an SI engine. In addition, it produces more torque and better fuel economy than an SI engine.It has the highest thermal efficiency in internal combustion engines because of its high compression ratio which lies between 14:1 and 25:1. This makes it to reach upto an efficiency of 55%.
These are some of the basic differences between diesel engines and petrol engines. Apart from these, internal combustion engines is differentiated in terms of their designs, mounting, fuel type used, positioning of the spark plug in SI engines and positioning of the fuel injector in CI engines, power capacity, etc.
Well, now you can say which type of the engines you travel on and how do they work.

