What is the difference between petrol and diesel engine in automotive definition
The main difference between petrol and diesel engines lies in the way they ignite fuel to produce power.
- Petrol engines use a spark ignition system. They compress a mixture of air and petrol fuel, and then the spark plug ignites the mixture, causing it to explode and drive the piston down. This process is known as the Otto cycle. Petrol engines typically have higher RPMs (revolutions per minute) and are often used in lightweight vehicles like cars and motorcycles.
- Diesel engines use a compression ignition system. They compress only air in the combustion chamber, and then diesel fuel is injected into the heated, highly pressurized air. The fuel ignites due to the high temperature and pressure, driving the piston down. This process is known as the Diesel cycle. Diesel engines typically have lower RPMs but higher torque (force), making them more suitable for heavy-duty applications such as trucks and larger vehicles.
Other differences between petrol and diesel engines include fuel efficiency, cost, and emissions. Petrol engines tend to be more fuel-efficient at higher RPMs, while diesel engines have better fuel efficiency at lower RPMs. Diesel fuel is generally less expensive than petrol, but diesel engines themselves tend to be more expensive due to their more robust design. In terms of emissions, petrol engines produce higher levels of CO2, but diesel engines emit more particulate matter and nitrogen oxides.