Diesel vs gas engines: what's the difference?

 They burn different types of fuel, but that's just the beginning. Here's what you need to know when comparing diesel...

This is the story of diesel versus gas engines: diesel engines burn diesel, petrol engines burn petrol.


Different ways of igniting fuel:

Apart from the fuel differences, the most significant difference between diesel and gas engines is the way in which each ignites the fuel.


A diesel engine compresses the air in the combustion chamber until it is hot enough to ignite the fuel, which is injected into the chamber through an injector. A petrol engine, on the other hand, uses spark plugs to ignite the mixture of fuel and air at the correct time. In engineering circles we describe the ignition methods as compression ignition and spark ignition.

Diesel = more durable construction

Diesel engines are low revving, high torque engines that typically last longer than petrol engines. Engineers often use larger, heavier and more robust components because diesels are primarily designed to work - and work hard.


It's not uncommon to see turbocharged diesel pickups with diesel engines covering 300,000 miles (483,000 km) and off-road trucks with diesel engines covering 1 million miles (1.6 million km). Impressive, but even more so when you consider that these trucks are pulling or hauling heavy loads.


Modern diesel engines in turbo-diesel pickups are typically rated at over 400 horsepower and 900 foot-pounds of torque. An off-road truck engine can produce over 600 horsepower and over 2,000 foot-pounds of torque. These numbers are huge compared to the 400 horsepower and 500 foot-pounds of torque of a typical big-block gasoline engine. Admittedly, the horsepower is similar, but the diesel engine excels at producing torque. If we know anything about traction and towing, torque rules.


Turbocharging and direct injection

So we've established that the diesel engine is a big, bad, powerful and long-lasting engine. But here are some more technologies that distinguish the diesel from the petrol engine.


Most diesel engines are equipped with turbochargers and direct fuel injection.


You're right, but they've only entered the scene in the last few years. The turbocharger clogs more air into the cylinders, while the injectors inject fuel directly into the combustion chamber helping to accomplish a lot.


- Increased power

- Reduced emissions

- Better fuel economy

- Easy to control injection timing


Now you see why the petrol engine world is replicating the diesel engine world.

Diesel versus petrol: why don't we all drive diesel?

Now you're asking, "Gee, if diesel engines are so good, why aren't we all driving diesel-powered cars?"


The answer is history and economies of scale.


Historically, diesel engines have had a poor reputation

Generally speaking, gasoline engines are much quieter and most Americans prefer to listen to the radio in their cars without having to crank it up to deafening levels to cancel out engine noise. Diesel engines have come a long way and recent technology has made them much quieter. But they are unlikely to be as quiet as petrol engines.


Many people still associate diesel with the black-smoking, foul-smelling engines of years gone by. Thanks to modern exhaust gas treatment units and the introduction of low sulphur diesel, the diesel produced today is much cleaner.


It is difficult to fit a diesel engine in a small car

In addition, we are moving to smaller vehicles to improve fuel economy. It is difficult to take a large diesel engine and downsize it to fit today's smaller vehicles.


Yes, some car manufacturers are playing in this area, but there are far fewer small diesel vehicles than petrol vehicles. Can you imagine putting a diesel engine into a Mercedes Smart? The engine would consume the car and you would have to ride on top of it. I'm guessing some kind of convertible.


There are therefore major differences between diesel and gas engines.

We manufacture and sell petrol engines as a manufacturer of gas engines. If you have any questions about petrol engines, you can ask us fawde.