What is BS4 Engine? How BS4 Engine Works

What is BS4 Engine

The Bharat Stage 4 (BS4) engine represents a critical milestone in India’s journey toward cleaner vehicular emissions. Officially introduced on April 1, 2017, BS4 regulations were designed to address the escalating issue of air pollution caused by vehicles. As a successor to Bharat Stage 3 (BS3) standards, BS4 aimed to significantly reduce the emission of harmful pollutants from vehicles, thereby improving air quality and public health.

BS4 standards established more stringent emission limits for vehicles compared to the previous BS3 norms. The regulations applied to a broad range of vehicles, including passenger cars, two-wheelers, commercial trucks, and buses. For petrol engines, BS4 set limits on carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx), while diesel engines faced limits on CO, HC, NOx, and particulate matter (PM). These limits were specifically formulated to curb the release of pollutants that contribute to smog formation and respiratory issues.

To comply with BS4 standards, vehicle manufacturers had to incorporate advanced emission control technologies. For petrol engines, this typically involved the use of three-way catalytic converters, which facilitate chemical reactions to convert harmful gases into less harmful substances. Diesel engines, meanwhile, employed diesel oxidation catalysts (DOC) to address CO and HC emissions, although these were less effective in controlling NOx and PM compared to future technologies. Additionally, the BS4 regulations required a reduction in the sulfur content of fuels to up to 50 parts per million (ppm), aiming to further decrease the emission of sulfur oxides and particulate matter.

The BS4 transition also brought about notable improvements in vehicle performance and fuel efficiency. Vehicles with BS4 engines were designed to offer better drivability and reduced emissions compared to their BS3 predecessors. However, while BS4 engines marked a significant advancement, they were eventually superseded by Bharat Stage 6 (BS6) standards, which introduced even more stringent emission limits and advanced technologies such as selective catalytic reduction (SCR) and diesel particulate filters (DPF).

Overall, the introduction of BS4 engines marked an important step in India’s efforts to combat vehicular pollution. By enforcing stricter emission limits and improving fuel quality, BS4 standards played a key role in reducing air pollution and enhancing public health. The transition to BS6 standards, which followed, continued this progress by incorporating even more advanced emission control technologies and stricter regulations.

How BS4 engine works

A Bharat Stage 4 (BS4) engine operates with a focus on minimizing emissions of harmful pollutants, adhering to specific regulatory standards set by the Indian government. The primary technologies and processes involved in the functioning of a BS4 engine include advanced emission control systems, improved fuel quality, and sophisticated engine management.

Emission Control Technologies – In BS4 petrol engines, a three-way catalytic converter plays a crucial role in controlling emissions. This converter contains a catalyst, typically composed of platinum, palladium, and rhodium, which facilitates the conversion of carbon monoxide (CO) into carbon dioxide (CO₂), hydrocarbons (HC) into carbon dioxide and water, and nitrogen oxides (NOx) into nitrogen and oxygen. This simultaneous reduction of multiple pollutants ensures that the exhaust gases are cleaner. For diesel engines, the Diesel Oxidation Catalyst (DOC) is used to convert CO and HC into less harmful substances, though its ability to handle NOx and particulate matter is limited compared to future technologies.

Fuel Quality and Engine Efficiency – The BS4 standards mandated a reduction in sulfur content in fuel to up to 50 parts per million (ppm). This lower sulfur content helps reduce sulfur oxides (SOx) emissions, which can contribute to particulate matter and environmental damage. It also enhances the effectiveness of catalytic converters and other emission control devices by preventing catalyst poisoning and ensuring more efficient operation. Improved fuel quality thus directly supports the engine’s ability to meet emission limits.

Engine Management Systems – The Electronic Control Unit (ECU) is integral to the operation of BS4 engines. The ECU manages critical engine functions such as fuel injection timing, air-fuel mixture, and ignition timing, optimizing these parameters to meet emission standards and improve fuel efficiency. Additionally, On-Board Diagnostics (OBD) systems continuously monitor the performance of emission control components. They detect and alert the driver to any malfunctions or inefficiencies, ensuring that the vehicle remains compliant with emission regulations.

Combustion Process – In a BS4 engine, achieving efficient combustion is key to reducing emissions. The engine maintains a precise air-fuel mixture to ensure complete combustion, which helps minimize the formation of unburned hydrocarbons and carbon monoxide. By optimizing combustion temperatures and pressures, the engine reduces the production of nitrogen oxides and particulate matter. This careful management of the combustion process enhances overall engine performance while adhering to emission standards.

Additional Technologies – Some BS4 diesel engines may also incorporate Exhaust Gas Recirculation (EGR) systems. The EGR system recirculates a portion of exhaust gases back into the engine’s intake, lowering combustion temperatures and thereby reducing nitrogen oxide (NOx) emissions. This additional feature helps diesel engines meet the stricter emission limits imposed by BS4 regulations.

In summary, a BS4 engine integrates a range of technologies and systems designed to minimize emissions and improve environmental performance. Through advanced catalytic converters, improved fuel quality, precise engine management, and additional technologies like EGR, BS4 engines represent a significant step forward in reducing vehicular pollution and enhancing air quality.