1. Compression Ratio: Diesel engines have a much higher compression ratio than petrol engines. This means that the piston compresses the air inside the cylinder to a much higher pressure before fuel is injected. To withstand this high pressure, the engine block, crankshaft, connecting rods, and pistons need to be stronger and therefore heavier.
2. Fuel Injection System: Diesel engines use a high-pressure fuel injection system, which adds weight to the engine. The system needs to be robust to handle the high pressures and temperatures involved in injecting fuel into the combustion chamber.
3. Larger Displacement: Diesel engines often have larger displacements (engine size) than petrol engines, which means they have more cylinders and bigger components. This inherently makes them heavier.
4. Turbocharger: Diesel engines frequently use turbochargers to boost power output. The turbocharger system, including the turbine, compressor, and associated piping, adds considerable weight to the engine.
5. Cooling System: Diesel engines tend to generate more heat than petrol engines. This means they require a more robust cooling system with larger radiators and water pumps, adding to their overall weight.
6. Stronger Materials: Due to the higher combustion pressures and stresses, diesel engines often use heavier and more robust materials like cast iron for their engine blocks and components.
7. Exhaust System: Diesel exhaust systems are typically larger and heavier than petrol exhaust systems, due to the higher exhaust gas flow and the inclusion of exhaust gas recirculation (EGR) systems.
8. Emissions Control System: Diesel engines often have more complex emissions control systems, such as diesel particulate filters (DPFs) and selective catalytic reduction (SCR) systems, which add weight to the engine.
In summary, the combination of higher compression ratio, stronger materials, larger displacement, and more complex systems contribute to the heavier weight of diesel engines compared to petrol engines.
