What is the difference between BS4 and BS6 Engine?

BS4 and BS6 refer to the emission norms or standards set by the Indian government for vehicles. These standards define the permissible limits for pollutants emitted by internal combustion engines, including cars, motorcycles, and commercial vehicles. Here’s a comparison of BS4 and BS6 engines:

1. Emission Limits: BS4 (Bharat Stage 4) is an earlier and less stringent emission standard, while BS6 (Bharat Stage 6) is the latest and stricter standard. BS4 engines have higher emission limits for pollutants like nitrogen oxides (NOx), particulate matter (PM), carbon monoxide (CO), and hydrocarbons (HC), compared to BS6 engines. BS6 engines have significantly lower emission limits, leading to cleaner exhaust gases.
2. Fuel Quality: The introduction of BS6 norms also brought about a change in fuel quality. BS6 engines require ultra-low sulfur fuel (10 ppm sulfur content) compared to BS4 engines, which can tolerate higher sulfur content (50 ppm sulfur).
3. Technology and Components: To meet the stringent BS6 norms, manufacturers have had to upgrade engine technology and components. BS6 engines typically feature advanced technologies such as improved fuel injection systems, optimized combustion chambers, enhanced exhaust after-treatment systems, and more sophisticated engine management systems. These upgrades help in reducing emissions and improving fuel efficiency.
4. Impact on Vehicles: Due to the stricter emission standards, BS6 engines generally have higher manufacturing costs. The implementation of BS6 norms led to a rise in vehicle prices because manufacturers had to invest in research, development, and technology upgrades. However, BS6 engines are more fuel-efficient and emit significantly lower levels of pollutants, contributing to improved air quality and reduced environmental impact.
5. Availability: BS6 norms were implemented in India from April 1, 2020. Since then, all new vehicles launched in the country need to comply with BS6 standards. As a result, the availability of BS4 vehicles has reduced, and most manufacturers have transitioned to producing BS6-compliant vehicles.

It’s worth noting that BS6 norms are specific to India, while other countries may have their own emission standards such as Euro 6 in Europe. The transition from BS4 to BS6 was a significant step towards reducing vehicular pollution and promoting cleaner and greener transportation in India.