The main differences between a petrol and a diesel engine are that the diesel is ‘Compression Ignition’ and the petrol engine is ‘Spark Ignition’. Diesel engines have an ideal air:fuel ratio of 20:1 and Petrol engines have a ratio of 14.7:1. Diesel engines are often cheaper to run than Petrol engines aswell, below are the advantages for both petrol and diesel engines.
Diesel
- No Spark Plugs
- Greater Thermal Efficiency
- Cheaper to run, more economical
- Greater torque output
- Torque output lower down rev range
- More suitable to commercial vehicle
- No ignition system, no high voltage wires avoids the risk of water ingress
Petrol
- Quieter
- Less Vibration
- Lighter than Diesel
- Requires less careful maintenance
- Less Compression Pressure
- Lighter starting system
- Less complex outlay