Difference between BS4 and BS6 compliant vehicles

BS is basically a norm known as Bharat Stage norms which are defined for the engines and also for the fuel. BS norms are equivalent to the EURO norms which are accepted globally.The major difference between the BS IV and BS VI or the need to shift to BS VI is for cleaner vehicular emissions. BS VI vehicles will be more effective for the diesel engines, which releases a huge amount of sulphur in the emission. Presently the BS IV engines release around 50PPM(Parts per million) of sulphur and shifting to BS VI will drastically reduce it’s quantity to 10PPM. So BS VI engines are more cleaner and cause less environmental pollution( one of the biggest problem of the future generation).

It will also reduce the other harmful content( NOx, PM, CO,HCs etc.) CO and Hydrocarbons are more prevalent in petrol engines whereas NOx and PM are more in diesel engines. The major objective of BS VI engines is to reduce the sulphur content in emission which is very harmful for health in the long term.

The BS norms are also applicable for the fuel, presently in India BS IV fuel is available except in some places like Delhi where govt. has rolled out the BS VI fuel. But remember the overall shift from the BS IV to BS VI will cost a lot to the automobile companies and the oil refineries( which ultimately gonna increase the price of the vehicles), but it’s for the greater good.

There is no much of change in engine parameters of bs IV and bs VI Engines. Main changes are in the after treatment(exhaust after treatment) of the engine. Once the exhaust comes out of the Turbo Charger it passes through the after treatment which includes DOC (Diesel oxidation Catalyst) then DPF ( Diesel Particulate Filter) then SCR ( Selective Catalytic Reducer) and then ASC (Ammonia Slip Catalayst) which is an option to be fitted. The engine also consist of air control system such as turbo speed controller intake air throttle control valve or exhaust throttle control valve.

What is BSIV or BS4 engine then? 

BS4 stands for Bharat stage four emission norms and hence a BS4 engine is one which complies with norms laid down by the government. The Bharat norms are emission control standards that are based on the European regulations (Euro norms). They set limits for release of air pollutants from equipment using internal combustion engines, including vehicles. Typically, the higher the stage, the more stringent the norms. The BS IV norms were introduced in 13 cities apart from the National Capital Region from April 2010 onwards. According to the road map, the entirety of India was to be covered under BS IV by April 1, 2017. BS IV fuel was also to be made available across the country from April 1 2018 all over India. Another interesting and unexpected law under BS4 is AHO (All time headlight or automatic headlight on) according to which headlight on and off switch was removed. This version of motor bikes have come into Nepal as well, since last year and is still used by many people. Though due to this removal of the light control button and the light being on all the time, the bikes batteries have been taking quite a hit during the startup phase. Though the companies do allow the users to add the headlight buttons if they want but majority of the companies advise you to follow the BS4 rule of the headlights as well as the engine compliance.

What is BSVI or BS6 engine then? 

The Bharat Stage 6 (BSVI) norm is the sixth mandate for vehicular emissions and a much welcome change amidst the rampant air pollution in India. BS6 is a stricter, more restrictive norm that will give a jump start to India’s long battle with air pollution. With the roll-out of the BS6 norms, India will come at par with the US and European equivalent emissions norms.

A Bharat Stage 6 ready engine has major modifications to its components to make it cleaner and adhere to the BS6 emission norm. Modifications like improved fuel quality composition and a DPF (Diesel Particulate Filter) and SCR (Selective Catalytic Reduction) in diesel cars are put to use to make the vehicle BS6 ready.

BS6 vehicles have already begun production and many of the older BS4 bikes are getting their BS6 versions this 2020. Though the price will be increasing as the technologies used in  the BS6 variants will be costlier and will need more maintenance.

What are the main differences between BS4 and BS6 engines then?

  • The main difference between BS6 and the outgoing BS4 fuel is that the BS6 fuel contains 5 times fewer sulphur traces (10 parts per million) compared to BS4 (50 ppm). NOx (Nitrogen Oxide) level will be brought down by a staggering 70% for Diesel engine and 25% for Petrol Engines.
  • The BS6 will be bringing a huge number of changes, which are most significant being the mandatory OBD (On board Diagnostics) for all the vehicles  which are BS6 compliant.
  • RDE (Real Driving Emission) will be introduced for the first time that will measure the vehicle’s emission in real-world conditions against simulated conditions.
  • Introduction of DPF (Diesel Particulate Filter) and SCR (Selective Catalytic Reduction) for Diesel engines.

Can BS6 engines run on BS4 fuel?

The engines that run on BS4 or BS6 petrol will not have any problem running on either of the fuel variants as the fuel components do not change much at all. As for the diesel variant of the BS6 and BS4 engines, the case is vastly different as the sulphur traces in the BS4 fuel is much higher than that of the BS6 fuel. The BS4 diesel contains 50 ppm of sulphur traces while the BS6 fuel contains only 10 ppm of sulphur traces, that is 5 times less than the former.

Sulphur in diesel engines help to lubricate the engine as well ionise the fuel for it to be combustible and then be used to run the vehicle. As BS6 fuel has less sulphur the BS4 engine can wear out prematurely and can cause various damage to the engine itself.

On the other hand, if you use BS4 fuel on a BS6 engine, the high sulphur content can cause various problems. BS6 diesel engines have very sophisticated electronics and a re-developed exhaust system. With the introduction of DPF (Diesel Particulate Filter) and SCR (Selective Catalytic Reduction), using BS4 diesel with high sulphur content will drastically increase the emission (due to increased sulphur ppm) eventually clogging up the diesel particulate filter. This will also affect the fuel economy in diesel cars.

Note: The above article was written with help from various sources, all the sources havenot been mentioned, and would like to credit these sources for the valuable information that was used to create this article.

Leave a Reply

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