Torque is a measure of how much force acting on an object causes that object to rotate. You all would have noticed that ‘Nm’ figure on information leaflet of a vehicle. Ever wondered why diesel engines produce more torque than petrol engines. Here are the 5 main reasons specified by Jason Fenkse from Engineering Explained.
Higher Compression Ratio
Both diesel and gasoline engines convert chemical energy from fuel into mechanical energy through a series of explosions. The diesel internal combustion engine differs from the petrol engine by using highly compressed hot air to ignite the fuel rather than using a spark plug (compression ignition rather than spark ignition). Hence the compression ratio of a diesel engine is higher than a petrol engine.
Higher Speed of combustion:
Diesel engine’s combustion takes place at top of the stroke as the piston travels back down to cylinder whereas in petrol engine the stroke is short hence the diesel goes faster and increases rotations that result into amplified torque.
Bore and stroke size:
Petrol engines have shorter stroke and wider bore which doesn’t let the Piston travel far. With diesel, the stroke is longer that result into increased torque equation as per meaty mathematics: Torque = F ( Force) x r(distance measured from the axis of rotation to where the linear force is applied)
All modern diesel engines are equipped with turbocharger which provides healthy amount of airflow. It uses an air compressor that pushes air into cylinders, allowing them to burn more fuel in less time and more power. More over this technique makes diesel engine more fuel efficient too.
Higher energy density:
Diesel’s energy density is higher than Petrol and hence more energy means more power.