The Differences Between Bs4 (BSIV) And Bs6 (BSVI) Engine

Pollution, Bs4, and Bs6:

Pollution is highly hazardous and deadly. Of all the types, air pollution is one of the most serious and concern worthy environmental issues of the urban cities of India wherein the majority of the population of the country living in these areas is exposed to poor or hazardous air quality. The day by day growing urbanization in the country has resulted in a remarkable escalation of the number of automobiles.

The subsequent mobbing of the vehicles on the road increases, making automobiles the main source of air pollution in India. The officials of the country have implemented a huge number of measures for the improvement of the air quality in cities. These measures and reforms include the improvement in the fuel quality, formulation of necessary legislation and enforcement of vehicle emission standards, improved traffic planning, and management, etc.

Difference in BS4 & BS6 Engine | BS4, BS6 Full Details | DayTooDays

One of these important measures and regulations includes BHARAT STAGE EMISSION STANDARDS (BSES). The government of India has authorized that all vehicle manufacturers, both two-wheelers and four-wheelers, should manufacture, sell and register only BS6 (BSVI) engines vehicles from 1 April 2020. The first emission was introduced in the year 2000 and came to be known as `India 2000`. After the year 2000, the emissions BS2 and BS3 were introduced in the year 2005 and 2010 respectively.

In the year 2017, BS4 (BSIV) was introduced by the officials of the central government. The other emission-related changes introduced by the central government included tailpipe emissions, Electronic Control Unit (ECU), ignition control, etc. The most evident modification was the AHO (Automatic Headlamp On), which is one of the norms under the BS4 (BSIV) which accommodated the safety aspect of the new emission standards.

Herein, we will discuss the differences between the previously manufactured BS4 (BSIV) engines and the newly developed BS6 (BSVI) engines:

Fuel Type

Pollutant Name

BS4 (BSIV) Engine

BS6 (BSVI) Engine

Petrol passenger vehicle

nitrogen oxide limit

(no ) limit

particulate matter limit

nitrogen oxide limit

< 80 mg >



< 250 mg >


< 60mg >


< 4.5 mg / km

< 80 mg >


Diesel passenger vehicle

particulate matter (PM) limit


< 25 mg >

 < 300 mg >

< 4.5 mg / km

 170 mg / km

Below are the pollution emission norms of BS4 (BSIV) vs. BS6 (BSVI) for a cleaner and greener environment to avoid and get over pollution and global warming. These norms help to control the pollutant, hazardous and deadly emissions released by increasing vehicles on the roads.

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  • The BS6 (BSVI) is the 6th emission criteria and category that are introduced to reduce pollution levels as compared to the BS4 (BSIV) emission norms. Both of these criteria and categories are the maximum emission norms which set the maximum pollution from the exhaust of the motor vehicle.
  • Meanwhile the BS4 (BSIV) emission norm permits the vehicles to emit not more than 80mg/km of NO2 (nitrogen oxides), the BS6 (BSVI) emission norms have reduced it to 60mg/km. The Particulate Matter (PM) for petrol vehicles has been restricted to 4.5mg/km in the BS6 (BSVI) emission command.
  • Under the BS6 (BSVI) criteria or norm, the limit of the engine to emit has been radically and considerably diminished or moderated. While the norm for NOx from diesel vehicles in BS4 (BSIV) is at 250 mg / km, it is diminished to 80 mg/km in BS6 (BSVI) emission norms. The HC + NOx has been diminished from 300 mg/km in the BS4 (BSIV) to 170 mg/km, while the PM level has been diminished from 25 mg/km to 4.5 mg/km.
  • The norms related to BS6 (BSVI) are not just restricted to motor vehicles but also possess the regulations to be followed by the fuel being dispensed. Nitrogen and sulfur oxides play a crucial role in petrol and diesel. As compared to the fuel emission levels of BS4 (BSIV), the BS6 (BSVI) emission has much less sulfur and NOx. While the content of sulfur in BS4 (BSIV) fuel is 50ppm, it is five times lower in the BS6 (BSVI) fuel, which is at 10ppm. As for nitrogen oxide, the permitted level has been reduced by 70% and 25% for diesel and petrol engines, respectively.
  • From the 1st April 2020, when the BS6 (BSVI) norm was established and brought about in the country, the fuel will also be bestowed across the country’s petrol pumps from the same date onwards. One can also use BS6 (BSVI) fuel in BS4 (BSIV) vehicles.Top 5 Mileage Bikes In India 2021 Best Mileage Bikes In India Know The  Price Mileage And Specifications - पेट्रोल 100 रुपये के पार: ये हैं देश की  ज्यादा माइलेज देने वाली
  • For proper lubrication inside the engine, sulfur plays a crucial role. However, for the emission of BS6 (BSVI) fuel, the sulfur is much lower as compared to the BS4 (BSIV) fuel. This is addressed with extracts that act as lubricating agents.
  • With the BSVI norms, the Selective Catalytic Reduction (SCR) and Diesel Particulate Filter (DPF) were incorporated to assess the emission levels of the BS6 (BSVI) motor vehicles. However, this was not an element of the emission norms set of the BS4 (BSIV).
  • Real Driving Emission (RDE) has also been introduced in the BS6 (BSVI) norms to ensure that the emission levels from the automobiles are measured on a real-time basis and this important regulation was not a part of the BS4 (BSIV) norms.
  • Another addition to the BS6 (BSVI) norms is the Onboard Diagnostic (OD) which was not authorized in the BS4 (BSIV) norms.
  • According to the new norms, the BS6 (BSVI) vehicles using the BS4 (BSIV) fuel will not be permitted to adhere to the required emission norms due to higher levels. Hence, a BS6 (BSVI) vehicle only has to use a BS6 (BSVI) fuel to achieve the desired emission levels.


Hence, to ensure that your vehicle is not adding to the pollution levels of the air and atmosphere, make sure you switch and upgrade yourself from the BS4 (BSIV) to BS6 (BSVI) to create a clean, green, and pollution-free environment. 

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