What are BS3 and BS4 Engines?

BS is basically the emission standards given by Government of India to regulate the air pollutants coming from internal combustion engine. BS stands for Bharat Stage and are set by the central pollution control board. BS standard is generally applicable to all the vehicles that are running in the country.

You may have heard of other standards like Euro… in Europe and Tier 1, Tier 2, used in USA.

More the number assigned, less air polluting the engine or less pollutants, the engine is releasing. In India, the BS 4 Engines are applied for the NCR and some other cities while, BS 3 Engines are applied nation wide. Although, in coming years the BS4 engines will be applied nationwide i.e. the manufacturing of BS3 engines will stop.

The attached table from Wikipedia will help you more.

I would like to keep it short and simple by just giving the basic difference.

BS - Bharat Stage

History :-

·         BS Engine - 1991 for Petrol Ones, 1992 for Diesel Ones

·         Strictly followed the European Standards

·         BS-3 Introduced in 2010 in whole country

·         BS-4 Introduced in 2016 in only some major cities of India

Main difference is in the Technical Structure of the Engines which reduces the harmful gases emission by 80 %. Thats a huge difference isn’t it.

Note - The Greater the number after BS the more stricter is its norms so finally lesser is the pollution.