How BS6 Petrol and Diesel Engines Reduce Emissions

How BS6 Petrol and Diesel engines work to reduce emissions
How BS6 Petrol and Diesel engines work to reduce emissions

BS6 or Bharat Stage 6; the name has started to disrupt the automotive market yet again. With the onset of the new emission standards, the companies are rushing to clear up their stock before 1st April 2020.

With the new emission standards coming in on such short notice there is a great amount of pressure on all the three parties of the automotive market i.e. the oil companies, the government as well as the manufacturers.

The Bharat Stage Emission Standards (BSES) is the supreme authority of the country which decides the emission standards for the country’s two and four-wheeler vehicles. The authority follows the emission standards based upon the European emission standards.

Suggested Read: Should You Buy An Electric Car Or a BS6 Car In 2020?

One question that’s popping up in everyone’s mind is- “Why to change these emission standards on such short notice?”

We’re here to clear out all the fuss in your mind relating to how Bharat Stage 6 or BS6 engine work to reduce pollution.

What is Bharat Stage 6 (BS6)?

“BS” refers to Bharat Stage, which is an emission measuring yardstick for all the vehicles plying on the Indian roads. The BS emissions are decided by the Central Pollution Control Board under the helm of the Ministry of Environment, Forest and Climate Change.

The Bharat Stage 6 (BS6) is a stage of emission control set by the CPCB after a slew of stages, with the first standard coming in the year 2000, named ‘India 2000’, followed by BS2 and BS3 in the year 2005 and 2010 respectively. The current BS4 standards came into effect in 2017, after a long gap.

Latest: Indian Oil Launches BS6 Compliant Winter Grade Diesel

To fill up the time wasted for the long gap of seven years and in an attempt to reduce pollution standards the Government decided to take a long jump to BS6 while skipping BS5 completely.

BS6 vs previous emission norms

With every different stage, comes a few changes in the manufacturing of the vehicles and the emission standards. Here are a few changes that came in the past before BS6.

  • BS1 (Bharat Stage 1)

    It was the first stage to be formulated based on European Standards or the Euro 1 norms and was rolled out in 2000. The emission standards were also known as ‘India2000’.The Bharat Stage 1 required the manufacturers were required to retune the carburettor, the secondary air intake system, exhaust gas reconciliation system and a lot more.

  • BS2 (Bharat Stage 2)

    The BSII norms came into place in the year 2000 and the sale lasted till 2010. Multi-Point fuel injection had to be included by replacing the carburettor. The BS2 norms were considered to be successful keeping in mind the fact that during this period the emissions were reduced quite significantly.

  • BS3 (Bharat Stage 3)

    The Bharat Stage 3 emission norms came into effect in the year 2005, with the sale of the vehicles made mandatory after the year 2010. The BS3 emission norms in the vehicles led to lower emissions in petrol vehicles.

  • BS4 (Bharat Stage 4)

    The Bharat Stage 4 emission norms came in after a long wait in the year 2017. The newer norms required the manufacturers to add a bigger catalytic converter to minimize nitrogen-based emissions while also bringing a small change in the Engine Control Unit of the vehicles to ensure efficient combustion.

  • BS6 (Bharat Stage 6)

    The Bharat Stage 6 (BS6) will bring down and restrict the emissions from the tailpipe to 1.0g/km of Carbon Monoxide. The BS6 fuels will have a lesser amount of sulfur in it and involve more of additives. The BS5 emission norms were skipped by the standard body to curb the pollution by bringing in stricter norms.

Bharat Stage characteristics for Petrol engines

Stage Year of Rollout Carbon Monoxide Oxides Discharge Sulfur Content
BS3 2005 2.3g/km 0.35g/km 100 PPM
BS4 2017 1.0g/km 0.18g/km 50 PPM
BS6 2020 1.0g/km 0.16g/km 10 PPM

Bharat Stage characteristics for Diesel engines

Stage Year of Rollout Carbon Monoxide Oxides Discharge Sulfur Content
BS3 2005 0.64g/km 0.50-0.56g/km 100 PPM
BS4 2017 0.50g/km 0.25-0.30g/km 50 PPM
BS6 2020 0.50g/km 0.06g/km-0.17g/km 10 PPM

How does a BS6 engine work?

The BS6 engines work on the account of the Selective Catalytic Reduction unit, which is an advanced emissions control unit developed by the manufacturers to control emissions in a car using a reductant agent which is usually automotive-grade urea.

In Bharat Stage 6, (BS6) the SCR unit converts NOx (Nitrogen Oxide) into two harmless particles i.e. diatomic nitrogen and water using AdBlue or diesel exhaust fluid. The diesel fluid is made of urea and deionized water.

Read: BS6 Fuel Now Available in Delhi NCR

When exhaust gases from the engine come in contact with the AdBlue, the urea gets converted into ammonia and carbon dioxide and the ammonia later converts the gases into nitrogen and water vapour, thereby reducing pollutant emission from the engine.

What is an SCR?

The SCR or Selective Catalytic Reduction unit is a specially designed component in a BS6 engine, which is added to reduce emissions.

The SCR system reduces NOx emissions by increasing the combustion temperature, which reduces the production of Particulate Matter in the engine. The NOx although increases while doing so, but it is controlled by the SCR using catalytic reduction.

How is SCR beneficial?

The SCR is beneficial as it increases fuel efficiency to some extent and provides better power. With the inclusion of an SCR in the engine, the maintenance period is reduced and the life of the engine is increased.

The urea solution which is dosed into the fuel pump is suitable for the Indian climatic conditions and can be used to reduce the pollutants emitted from the cars.

Read: Discounts On BS4 Vehicles Are Lowering: Buy Before It’s Too Late

Although, due to its expensive application and complex nature, only a few carmakers use the SCR technology in their cars.

What is AdBlue?

AdBlue is a brand name for a special diesel exhaust fluid. The fluid is made from urea and deionized water that’s stored in the car. When the car’s engine runs, AdBlue does its job as it is mixed with exhaust gases and converts the pollutants from the exhaust gases into nitrogen and water which make it completely harmless for the environment.

From BS4 to BS6: Frequently Asked Questions

Will BS6 cars be more expensive?

The carmakers have already readied themselves to welcome the BS6 ready engines with some heavy investment in the R&D. The mainstream carmakers like Maruti and Honda already have some models which are BS6 compliant.

So, all in all, the petrol models shouldn’t have much increase in prices as there is only a small level of tweak that is required to make the cars BS6 compliant.

Although, diesel cars will be the ones which will have a major increase in price. The price difference between a BS6 model and an older model will have a difference of around ₹2.5 lakhs, which is a substantial increase.

Is BS6 fuel going to be more expensive than BS4 fuel?

Currently, BS6 fuels have been made available in most of the major cities around the country. The price difference between a BS4 fuel and BS6 fuel is currently negligible.

But it is predicted that with the onset of BS6 fuel vehicles plying on the Indian roads majorly, the Oil Marketing Companies are set to increase the prices for the BS6 fuel across the country.

Can BS4 models be converted to BS6?

From the legality point of view, it isn’t allowed. Moreover, when you convert your car into a BS6 model it will cost you dearly and might have some complications as well.

What’s going to happen to BS4 vehicles?

The existing BS4 vehicles will be plying on the roads normally, although no new BS4 vehicles will be registered or sold from April 2020 onwards, when the BS6 vehicle norms will be implemented.

How will BS6 engines impact CNG vehicles?

The manufacturers will have to make minor changes in the CNG vehicles to make them BS6 compliant. The CNG based BS6 cars will have a major impact on the market before the electric vehicles and the hybrid vehicles make an onset in the Indian markets.

What effect will BS6 fuel have on BS4 cars?

There is nothing to worry about if you are a BS4 model owner. The BS6 fuel will have a much lesser sulfur content than its predecessor, the BS4 fuel.

The sulfur content in BS6 fuels will be lesser than the older versions. The sulfur in fuels acts as a lubricant and burns effectively, however, the lesser sulfur content will be compensated by additives which will make the lubrication easier.

What’s next after BS6?

Although, there isn’t a new standard set yet by the governing body for pollution but, there have been speculations that the next stage after BS6 would be Real Driving Emissions standard, according to which the cars and its emissions will be measured in actual driving conditions rather than the current measurement yardstick, which is in a controlled environment.

What if you buy a BS4 model right now?

The manufacturers are currently offering huge discounts to clear off the stock of their BS4 models. The current ruling states that no BS4 models will be sold, manufactured or registered after 1st April 2020 which is the deadline set by the Government, after that only BS6 vehicles will be sold, manufactured or registered.

The consumers, on the other hand, don’t have to worry about anything as there is no set deadline for the BS4 models to stop plying on the roads. So, if you are going to buy a BS4 car right now, all you’ve got to look forward to is huge discounts being offered by car manufacturers right now.

Are BS6 norms the same as Euro6?

Although the Bharat Stage 6 emission norms are based on the Euro VI emission standards, there have been certain tweaks which have to be incorporated to make the emission norms more adaptable to Indian road conditions.

The fuel, average driving conditions, and the fuel type and quality have to be scrutinized to convert Euro6 into BS6, which is suitable for the Indian market.

How will BS6 affect the car’s performance and mileage?

With great power, comes great responsibility. While that’s not the case here. When you have the responsibility to cleaner air and fewer pollutants in the environment you will have to sacrifice the power, the performance as well as the fuel mileage. The BS6 engines might affect your car’s performance and mileage to a small extent.

Popular Read: The Indian Automobile Industry Highlights Of 2019

BS6 | Keep these points in mind

So, this is what can be concluded keeping in mind all the points covered above:

  1. The Bharat Stage 6 norms and fuel is surely going to disrupt the automotive market in India.
  2. To make sure that BS6 engines work thoroughly and efficiently there have to be several types of equipment that will increase business for the companies and small manufacturers dealing in such components.
  3. With BS6 the government can ensure that a strict implementation can bring down the pollutants released from vehicles in major metropolitan cities.
  4. The introduction of timely emission norms can ensure that the new and updated technology arrives in the Indian market on time. The BS6 might be succeeded by Real Driving Emissions standard, as mentioned above.
  5. While the manufacturers have already started bucking up their belts when it comes to following the emission norms brought in by BS6, the final hurdle will be the government policies to ensure that the older vehicles and their emissions do not nullify the effects of the new, more efficient vehicles.

Popular BS6 cars in India 2020

With the deadline to implement the BS6 vehicle norms sooner, the manufacturers have made sure that they comply with the rules and regulations. Here’s a list of the vehicles which are available in the Bharat Stage 6 models.

Popular BS6 Sedans

  1. Maruti Suzuki Dzire
  2. Hyundai Elantra
  3. Audi A6
  4. Mercedes Benz E Class

Popular BS6 Hatchback

  1. Maruti Suzuki Alto 800
  2. Toyota Glanza
  3. Maruti Suzuki Baleno
  4. Maruti Suzuki Grand i10 NiOS
  5. Maruti Suzuki Swift
  6. Maruti Suzuki S-Presso
  7. Maruti Suzuki WagonR 1.2 litre

Popular BS6 SUV

  1. Kia Seltos
  2. Jeep Compass

Popular BS6 Crossover

  1. Maruti Suzuki XL6

Read: How the Consumer Trend For Cars Is Changing in India


    • Hey Prashant,
      No, only the diesel engines get the SCR unit. Well, petrol engines when compared to diesel engines do not produce a large amount of NOx so they do not require a particular system to reduce the levels of nitrogen.


Please enter your comment!
Please enter your name here

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Exit mobile version