Differences Between Gas & Diesel Engines

Gas or Diesel...
Which Should I Choose?


Are diesel engines stronger than gas engines? Or are gas engines more fuel efficient? How is the strength of an engine defined? Read on to get a clearer view of the two engine types based on a number of important factors that you must keep in mind in order to make an informed purchase.

Gas Vs Diesel



Although, operating on the same principle, gas engines and their diesel counterparts are materially different from each other. The intrinsic principle behind both is that they create horsepower and torque from the combustion of a fuel. Yet owing to the very nature of the two fuels, there is a massive difference in the way the gas vehicles and diesel vehicles work.

One of the first things that you are told to remember as a new driver is to never put diesel in a gas tank, or vice versa. It can cause irreversible damage to the engine.

Here's a look at the similarities and differences between gasoline and diesel-powered engines.

How the diesel engine works

Much like gasoline engines, diesel engines are also internal combustion engines. This means that the fuel is internally compressed inside the cylinders of a typical diesel engine. The fuel is mixed with air and pushed into the cylinders where it goes through a comprehensive combustion process. When the fuel ignites, the piston comes down and propels the crankshaft into a downward motion. This mechanism is connected to the transmission of the car, which turns the wheels. The piston goes up and down in the cylinder of the engine, shoving the gas exhaust out through the tailpipe. This happens several times every second.

The Similarities Between A Diesel And Gas Engine

The number of cylinders directly affects the performance of a car. The greater the number of cylinders, the smoother the driving experience. This is because with a greater number of cylinders in the engine, the process of pistons going up and down happens multiple times, making the engine smoother to run. At the same time, it also complicates the process. A greater number of cylinders lend greater power to the car. The performance and vibration of a drive also depends upon the installation and configuration of the cylinders. The experience remains somewhat uniform for diesel engines and gas engines.

Differences Between Gas And Diesel



The most significant difference between diesel engines and gas engines is how the combustion process happens within the engine.

1. Spark Plugs

In gas engines, the gasoline fuel and air are compressed together and ignited by a spark stimulated by a spark plug.

In a typical diesel engine, there are no spark plugs. Diesel engines use extreme compression generated by the squeezing of the mixture to create sufficient thermal heat to ensure that the fuel combusts perpetually. For this reason, it is also known as a “compression ignition”.

This is also the fundamental difference between how a gas engine works vs a diesel-engine.

2. Fuel efficiency and Price:

A diesel engine is overall much more efficient and powerful than its gas variant. Diesel is certainly more expensive than gasoline, however, the prices vary across the US, and the difference is not as wide in other states.

Diesel fuel also has more joules of energy per unit. Thus, it is more efficient than gasoline as it provides more energy in the same amount.

3. Power Output:

The two fuels are also substantially different in terms of the power output. The output of the engines is measured in terms of horsepower and torque. Whereas the horsepower of an engine is strictly the measure of its power, the torque is a measure of the rate at which the engine produces the force on the driveline through the process of twisting.

Whereas both horsepower and torque are responsible for creating a powerful and overall efficient engine, a large amount of horsepower without the equivalent amount of torque to match will cause the vehicle’s acceleration to slow down. Torque is what propels your vehicle forward, and thrusts the engine into motion. This is why large vehicles such as trucks have diesel engines. Powerful engines help vehicles carry huge loads.

However, diesel engines do not rev up as high as other fuel-engines. They create less horsepower, and thus not ideal for fast cars. Diesel engines have high torque, but relatively low horsepower, whereas gasoline engines have more horsepower and less torque.

4. Drive experience:

Vehicles that run on gasoline are overall smoother and provide a better driving experience. You will feel the difference as soon as you step on the accelerator pedal. Diesel vehicles have brisk acceleration.

5. Reliability:

The most material difference between diesel engines and gasoline engines is that diesel engines run on a compression ignition. A compression ignition is not suitable for a gas engine at all. In fact, it can completely ruin the gas engine. A diesel engine is a lot more reliable as it is built to be tougher and more resistant. These engines are hard-wearing and more durable. They also require less care and maintenance.

A typical diesel engine is also a lot simpler and less complicated than a gas engine since it works without any kind of spark plugs. A diesel engine is also believed to generally last longer than a gas one. Also, the number of miles or hours that diesel engines can efficiently run for, without needing maintenance, is substantially greater.

It is therefore safe to say that engines running on diesel are certainly more efficient, powerful and reliable than most gas engines. However, if you are looking at performance and a smoother driving experience, a gas engine may be better.