Difference Between BS4 and BS6 Emission Norms : BS4 vs BS6

Bharat Stage emission standards (BSES) were introduced in the year 2000. Automotive emission standards have been set up by the Indian government to regulate the output of air pollutants from internal combustion engines in automobiles. BS4 and BS6 emission norms are equivalent to Euro4 and Euro6 respectively. 

Currently BS4 emission norms are in place in India. The government of India has decided to skip BS5 and implement BS6 emission norms by march 2020.  Don’t miss this article on self driving cars and how they work?

Emission NormReferenceYearRegion
India 2000Euro 12000Nationwide
Bharat Stage 2Euro 22001NCR, Mumbai, Kolkata, Chennai
2003NCR, 13 Cities
Bharat Stage 3Euro 32005NCR, 13 Cities
Bharat Stage 4Euro 42010NCR, 13 Cities
Bharat Stage 5Euro 5Skipped
Bharat Stage 6Euro 6April 2020Nationwide

BS4 vs BS6 Engines : What is the Difference

From BS-4 to BS-6 engines there are lots of improvements in engines. But the major focus is on saving the environment. Let’s try to find what will change from BS-4 to BS-6 in terms of engine emissions.

Petrol Emission Norms (in g/KM)
Emission NormCOHCNOxHC+NOxPM
Diesel Emission Norms (in g/KM)
Emission NormCOHCNOxHC+NOxPM
Source - Indian Emissions Regulations/ARAI

Advantages of BS6 engines over BS4 engines

BS-6 emission norms are adopted from Euro 6 norms. Euro 6 norms are already adopted in European countries. Following are the benefits of BS6 Norms.

  • Approximate 25% reduction in NOx emission in petrol engine and 68% reduction in diesel Engine.
  • PM emission will reduce by approximately 80% in diesel engines.
  • OBD2 will become mandatory for every vehicle. This will help in real time pollution monitoring. Read this article to know in detail about OBD Devices.
  • Real Driving Emission (RDE) in BS6 will measure the emission in real-world conditions and not just under test conditions.
  • Bharat Stage 6 norms will also change the way particulate matter is measured. It will now be measured by number standard instead of mass standard thereby, regulating the fine particulate matter as well.

Impact of moving from Bharat Stage 4 to Bharat Stage 6

Moving from BS4 to BS6 has the following impact. 

  1. Oil Refineries
  2. Automobile Emission System
  3. Automobile Industry
Oil Refineries

BS-6 compliant engines require BS-6 compliant fuel. Major difference between BS6 and BS4 fuel is the presence of sulphur. In BS-6 fuel sulphur amount is reduced from 50 ppm to 10 ppm. For that oil refineries need to improve their oil quality.

Effect of BS-6 Fuel on Existing Vehicles : BS6 fuel will not have any bad effect on old vehicles. But this may help in reduction of emissions in existing vehicles as well.

Automobile Emission System

To upgrade from BS-4 to BS-6 norms vehicle exhaust systems need upgrades. A NOx sensor is added in the BS-6 exhaust system. And to reduce NOx gases amount from exhaust AdBlue Liquid is sprayed on exhaust gases. In BS-6 compliant vehicles an adblue tank is also added.

Automobile Industry

For automobile companies moving from BS4 to BS6 is a challenging task. They have to develop BS6 compliant vehicles. Major change is in the vehicle exhaust system. This will also increase the vehicle price.

Because of BS6 norms, one of the biggest manufacturers in India, Maruti Suzuki decided to stop the production of diesel vehicles.

To sum up, BS6 vehicles will help in reducing air pollution. Conversion of vehicles from BS4 to BS6 will also have an impact on vehicle prices. Prices of diesel vehicles will increase more compared to petrol vehicles. 

We will keep adding more information on bs4 vs bs6 vehicles. Please add your suggestions, comments or questions on the difference between bs4 and bs6 engines.

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