1. Fuel Properties:
- Petrol (Gasoline) is a volatile fuel that readily vaporizes at atmospheric conditions. Unlike diesel fuel, petrol forms an air-fuel mixture prior to combustion.
- Diesel, on the other hand, is less volatile and requires higher temperatures and pressures to vaporize. It operates on the principle of direct fuel injection into the combustion cylinder.
2. Engine Operating Principles:
- Petrol engines generally operate on a spark-ignition basis. The fuel-air mixture is compressed and then ignited by a spark plug. This process allows petrol engines to run smoothly at high revolutions per minute (RPMs) due to the rapid combustion of the air-fuel mixture.
- Diesel engines, however, utilize compression ignition, where the high pressure and temperature generated by the compression stroke cause the diesel fuel to self-ignite. As diesel is less volatile, it doesn't require a spark plug for ignition.
3. Injector Design and Requirements:
- Petrol injectors are designed to deliver a precise amount of fuel and create a proper air-fuel mixture. They inject the fuel in the form of a fine spray to ensure efficient vaporization and combustion.
- Diesel injectors, on the other hand, are built to handle the high pressures required for direct fuel injection into the combustion chamber. They are designed to withstand higher temperatures and pressures compared to petrol injectors.
Since diesel fuel requires direct injection at high pressure, the use of injectors becomes necessary in diesel engines. Petrol engines, with their preference for a pre-mixed air-fuel mixture and spark ignition, do not require the high-pressure injection system employed in diesel engines. As a result, injectors are not commonly used in traditional petrol-powered vehicles.
