Key Differences Between Petrol and Diesel Engines
- Details
- 24 January 2019

There aren’t that many technologies initially developed in the late 1800’s that are still going strong today, but diesel fuel has to rank as one of the most successful.
The process has undergone continued revisions since then, with over a hundred years’ of research and development resulting in a reliable fuel source that keeps millions of vehicles and machines going today.
The difference inside
One of the most significant differences between the two systems is the compression ratio inside the combustion chamber. This measures the difference between the amount of air and fuel being forced together in the engine’s cylinder. Diesel engines sport a compression ratio that is over three times what is found in a petrol engine, with Rudolf’ Diesel’s original schematics listing 500 psi. Of course, Rudolf’s original designs tended to blow up during their development, so that number was drastically modified before commercial release.
Igniting the fuel source is also handled very differently in the two systems. In a standard petrol engine, a spark plug sits inside the cylinder head and makes a precisely-timed, minutely-sized spark of flame that makes the mixture of fuel and air in the chamber explode. This, in turn, drives the piston back down into the chamber and continues the vehicle’s momentum.
A bright spark
Diesel engines, on the other hand, do not have spark plugs at all. Instead, they rely on a particular rule of thermodynamics where a mixture of fuel and air placed a highly-pressurised chamber can be made to ignite simply from the friction generated by the air pressure. Not only does this save money on worn-out spark plugs, but the engine can be made to run smoother than the alternative since the pressure remains stable at all times. A “glow plug” is sometimes used to overcome cold temperatures outside the engine when the engine first starts.
The reliability offered by diesel fuel engines continues to astonish as the years progress. Some diesel engines have reported over 800,000 kilometres of service, and new innovations like turbocharging and direct injection have further refined the platform.
Reliability is one of the key reasons Bulk Fuel Australia has been operating so successfully for ten years now. We service a wide range of industries to provide a reliable source of diesel fuel anywhere across the country, so contact Bulk Fuel Australia today for more fuel for thought.