Know the Difference between BS3 and BS4 Engine

Undoubtedly the engine is the heart of any vehicle – be it motor vehicles, buses, trucks,tractors or construction equipment. When it comes to emission norms and engine changes,it is certainly a major technological shift because any change to the engine will reflect on the overall efficiency and performance of the vehicle.

Bharat Stage (BS) Emission Standards

As the world realised the growing importance of reducing carbon footprint and countries adopted stringent measures for controlling polluting vehicular emissions, India too introduced stricter emission norms. Bharat Stage Emission Standards (BSES) were first put in place in 2000 by the Government of India, in a bid to control air pollution from vehicular engine emissions.

For BS standards to be followed, updating the engine from previous to next-gen becomes necessary. So what does the shift from an earlier standard to next-gen BS emission norms really mean as far as vehicle product development is concerned? And how does it impact the crucial engine construction and performance?

New BS Standards for Auto vs. Construction Equipment (CE) Vehicles

Firstly, the transition in BS emission norms has been done in a calibrated manner keeping in mind different categories of vehicles and engine type.

From April 1, 2020, there has been nationwide implementation of Bharat Stage VI or BS6 norms (moving from BS4) for all new 4-wheelers manufactured, sold and registered.

However, the same norms are not applicable for the construction equipment industry where the shift in BS emission standards has been from BS3 to BS4. Also, as announced recently, the revised implementation date of BS4 norms in construction equipment vehicles is April 1, 2021 instead of the earlier ruling for October 2020.

For manufacturers, complying with the updated new regulation is in fact an opportunity to introduce latest and improved technology in their vehicles. Construction equipment vehicles will now be fitted with a BS4 diesel engine to replace the earlier BS3 diesel engine.

BS3 vs BS4 Engine

So let’s get into the nuts and bolts to understand the difference between BS3 and BS4 engine and how the phasing out from old to new-gen will affect engine performance.

At a top level we need to understand that a BS4 engine is able to manage and control evaporative vehicular emissions much better than a BS3 engine, resulting in a cleaner, less polluting vehicle.

Take a look at the change in emission levels from BS3 to BS4 for CE vehicles based on their engine power output.

The big change is about 90% reduction of PM (particulate matter) in BS4 engines higher than 50 HP. The highly toxic Nitrous Oxide (NOx) vapour emissions go down by a whopping 92% in BS4 engines higher than 75 HP.

BS3 vs BS4 Diesel Engine:

The major technology shift is that BS4 diesel engines have to use the more advanced common rail technology instead of the old direct injection technology. Although, most OEMs had already made the shift to Common Rail Direct injection (CRDi) when BS3 was announced. This was necessary so that their diesel engine powered vehicles were compliant with the new emission standards.

Another important change now to meet BS4 norms is that BS4 diesel engines have to be fitted with a bigger more powerful catalytic converter known as a Diesel Oxidation Catalyst(DOC). This mandatory fitment in diesel vehicles makes the fuel combustion process more efficient and reduces emission of harmful hydrocarbons and carbon monoxide.

Also, all diesel vehicles in the new BS4 era have to be fitted with an Exhaust Gas Regulator or EGR, and a Urea injector called Selective Catalytic Reduction (SCR). The latter cuts down NOx vapour emissions by breaking it down and converting NOx molecules into Nitrogen and H2O.

Apart from adopting newer engine technology, there are electronically-driven changes too when it comes to differences in BS3 and BS4 norms. To be deemed BS4 compliant, vehicles need to have On Board Diagnostics (OBD) whereby an in-vehicle electronic panel will continuously monitor engine performance and display the vehicle’s vital stats in real time.

In conclusion, it needs to be appreciated that for the construction equipment business, conforming to the new BS4 standards as per stated timeline, has led to manufacturers making huge investments in expensive technology, leading to the benefit of an entire latest gen of advanced machines.