Question

Why is compression ratio for si engines is less than that of ci engines

Answer 1

Most vehicles on the road are powered by internal combustion engines. The most common internal combustion engines for vehicles are fuelled with petrol or diesel. In Hong Kong, private cars are mostly powered by petrol internal combustion engines, while commercial vehicles e.g. buses and trucks are driven by diesel internal combustion engines. Although both engines have similar structures, they have significant differences in terms of operation, energy efficiency, and the amounts and types of emission they produce.