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BS6 Engine technology

BS-VI engine is the latest and ongoing technology according to the norms of BSES. It is the 6th standard norm under BSES to control pollution resulting from vehicle emissions. Full form of BSES is Bharat stage emission standards. BSES are the standards set for the emission of pollutants from the vehicles to make a check on air pollution taking place through autogas discharge. The purpose of these norms is to reduce and control the air pollution through automobiles in India as much as possible.

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Coming to the working scenario of BSES, BSES standards were established by the Government of India and now they are governed and managed by the Central Pollution Control Board which comes under the Ministry of Environment, Forest and Climate Change. The first norm of BSES was introduced in India in 1991 for petrol engines and 1992 for diesel engines. Coming back to BS-VI engine, it is the most recently introduced technology under the BSES norms and was announced mandatory on 1st April 2020 in the entire country as the Supreme Court of India declared ban on BS-IV. Actually, due to increased pollution in Delhi, the Ministry of Petroleum decided to bring BS-VI fuels in Delhi in 2017 itself but automobile manufacturers were not technically ready and planned it for 2020 so BS-VI could not make it up before 2020.


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As the technology changes towards betterment it shows a bit hike in prices but in return, it could save many people from harmful lung diseases caused by harmful gas emissions from vehicles so it balances the cost hike of BS-VI vehicles. Talking about the benefits, one of the major technical advantages of BS-VI engines is in terms of sulphur and nitrogen oxide. It has been noticed that sulphur traces in BS-VI engines are found almost 5 times lower than they are found in BS-IV engine emissions. Focusing in the terms of petrol and diesel engines, BS-VI petrol engines lowers the emission of sulphur oxide, nitrogen oxide, carbon monoxide and other toxic hydrocarbons. BS-VI Diesel engines presented a delightful performance by cutting down particulate matter emissions to half, hence contributed efficiently in pollution control. However, BSES norms for vehicles do not show a great difference in mileage but still small hikes can be seen in the fuel economy of the vehicles. Not only in the motor vehicles emissions but sulphur and nitrogen oxides are already present in petrol and diesel, therefore even the fuels were saturated and modified according to the BS-VI engines which consist of less toxic oxides so that the emission could be less harmful. Even the fuels for BS-VI engines are made available in India from April 2020. There are many benefits of using a vehicle with BS-VI engines and hence BS-VI engines should be promoted in India. 

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There’s nothing vast in this norm, it only states the amount of cut down of toxic emissions to be done essentially. BS-VI was announced in April 2020, but came into the proposal in 2017 observing the drastic increase in the air pollution in Delhi, hence considering the serious consequences some new things have been added to this norm that weren’t there in the last several BSES norms. Till now the BSES norms used to mention about sulphur and nitrogen contents in the vehicles’ smoke emissions but in BS-VI, control on hydrocarbons and particulate matter (PM) has also been added to ensure more safety in the terms of increasing air pollution. The Bharat Stage Emission Standards 6th norm (BS-VI) says, vehicles running on petrol will have to reduce their nitrogen oxide emission by 25% and vehicles running on diesel will have to reduce their hydrocarbons and nitrogen oxides emissions by 43%, nitrogen oxides levels by 68% and particulate matter levels by 82%. Control board has made some serious changes especially for diesel engines which may give positive results in return.

Why did BS-V engines never come into play?

At present concept of both the norms are dissolved under a single standard i.e. BS-VI. BS-V norm was skipped by the Control Board, though there wasn’t a huge difference between the concepts of BS-V and BS-VI but this isn’t the reason why BS-V never got introduced. The main reason is the long interval between BS-III and BS-IV, as it took 2017 for BS-IV to come into existence in the entire country and with the conditions of Delhi that was getting worse in 2018, it was important to soon get a new and advanced emission norm. So BS-V was skipped and directly BS-VI was introduced by adding on some more advanced requirements in the ongoing concept.


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Looking back at the history of these emission norms, before 2020 our vehicles were running on BS-IV engines which were introduced in 2017, before this BS-III came in 2005 and got implemented all over India in 2010 even before that we used to follow BS-II that was introduced in 2000.

But major changes can be seen in the concept of BS-VI, as it is a precise and stricter norm as compared to BS-IV. BS-VI norms stated the emission of nitrogen oxides at 250mg/km (reduced to 80mg/km in BS-VI) for diesel engines and emissions of hydrocarbons at 300mg/km (reduced to 170mg/km in BS-VI), this major change will surely play an important role in controlling the air pollution through vehicles. Other than emissions control, the crucial role that can be observed is the BS-VI fuel contains very low sulphur traces and nitrogen oxide levels are cut down to up to 70% in diesel and 25% in petrol, so that the traces of pollutants will be automatically reduced at the time of emission.

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Other than these pollutants reduction steps, some features have also been declared as mandatory in BS-VI engine vehicles like On-board diagnostics which is a really useful feature to keep a check on emission information of the vehicle as it provides the status of a vehicle’s particular system. One more feature is namely Real Driving Emission, that will measure the real-world emission status of the car i.e. checking the amount of sulphur and nitrogen traces getting emitted by the car while driven on the road.

BS-VI norms contain a lot of overall advantageous concepts, but coming to the drawbacks, there are no such drawbacks of a BS-VI engine but just one matter of concern and that is its price. But price will increase with an updated technology and in return, it is giving us a lot of benefits, so overall it’s a very convenient and useful norm.

Hey there ! I'm Palash , I'm a blogger / content writer by profession. Being an automobile enthusiast I create blogs on latest news , updates and reviews about automotive industry. Stay tunned for more.

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