Gasoline Engines Vs Diesel Engines: Which is Better?

Gasoline engines vs diesel engines is a big-time debate by most car owners and buyers – especially people who are shopping around for their first car.

But does it matter if you pick a car with a gasoline engine over the diesel engine alternative, or vice versa? Between gasoline engine and diesel engine, which is the best to buy?

Well, both types of engines perform differently and have their unique benefits. The combustion procedure of diesel engines is different from that of gasoline engines, and this slightly affects how both engines perform.

Diesel fuel is thicker than gasoline; thus, it evaporates slower and has more density/energy; this makes you experience higher fuel economy with a diesel engine than with gasoline engines.

Explaining the Differences Between Diesel Engines and Gas Engines

Both diesel and gasoline engines have one thing in common, which is, that they’re both designed as ICEs – Internal Combustion Engines. An internal combustion engine is a type of engine that converts chemical energy (from the fuel) to mechanical energy needed to operate the engine and its components – to keep the car moving.

Particularly, the word “Combustion” refers to the procedure whereby fuel (gasoline or diesel) is converted into mechanical energy for a car to move. This method/procedure can also be called “Explosions.” Well, gasoline engines and diesel engines undergo combustion processes, but in different ways.

So to say, the main difference between these two types of engines – gasoline and diesel – is how they carry out the combustion process.

In ICEs, the air is sucked into the engine chambers where it gets mixed with fuel (gas or diesel) and then compressed to generate enough power that would drive the engine pulleys and components.

Mainly, the power generated in the chambers is sent to the engine pistons and the crankshaft. Now, when the crankshaft activates, it pushes the transmission to work, and this act, in turn, moves the wheels of the vehicle.

Coming to the piston, it helps to remove combusted (waste) gas from the engine through the exhaust tailpipe. Well, this procedure may look cumbersome but it happens really quick, and of course, it happens repeatedly, multiple times per second – as long as the car is in motion.

However, after air and fuel are mixed in the combustion chamber, the subsequent process, which is igniting the piston, crankshaft, and other important components, does not happen in a similar pattern for diesel and gas engines, and this is where the differences kick in.

Combustion in a Gasoline Engine Vs Diesel Engine

Diesel engines do not use spark plugs – spark plugs are only present in gasoline engines. The function of the spark plugs is to deliver electrical current to “ignite” the piston and crankshaft. But since there are no spark plugs in diesel engines, how does the piston ignite?

Well, diesel engines use what is called “extreme compression” – a process that produces excessive heat/energy to ignite and power corresponding components. The actual name for this process in diesel engines is called “Compression Ignition.”

In addition, some diesel engines use carburetors or port injection systems to send fuel/air into the cylinders. Carburetors mix fuel and air before sending out the result into the combustion chamber, while port injection systems inject air into the fuel before the intake stroke.

Due to high compression on diesel engines, they typically offer more power, torque, and fuel efficiency. Now, what about gasoline engines?

Gasoline engines use spark plugs, and as such, the combustion process is not subject to extreme compression before the corresponding components are powered. If for any reason, a gasoline engine experiences extreme compression, the engine would most likely break down.

With pretty much explanations done so far, let’s look into the key differences between gasoline and diesel engines – one after another.

Gasoline Engines Vs Diesel Engines: Major Differences

1. Fuel Efficiency

Clearly, diesel engines save more fuel than gasoline engines, thanks to high compression. Also, diesel fuel contains about 12% more energy than gasoline fuel, and diesel further has about 20% more thermal efficiency than gasoline.

In practicality, diesel engines are poised to be able to go 25% farther than gasoline engines with the same amount of fuel. Furthermore, diesel engines are preferred for heavy-duty vehicles because it delivers higher thermal efficiency, more power, and more torque.

2. Price

Historically, diesel fuel is always costlier; but, in some fuel stations, you may see gasoline and diesel sold at the same price – with just slightly different in cents. Diesel is typically more expensive because of the benefits it offers.

3. Fuel Color

You can quickly tell between gasoline and diesel; gasoline is usually clearer, thinner, whitish, and has a typical scent. On the other hand, diesel is thick, reddish, or brownish.  

3. Life Expectancy

Diesel engines can run up to 1,500,000 miles before needing a major repair. Diesel engines are typically sturdier than gasoline engines because they are meant for heavy-duty applications.

From all angles, diesel engines typically last longer than their gasoline engines of the same specs and features.

4. Chemical Composition

Both fuels comprise hundreds of hydrocarbon molecules; in the US, petroleum-based diesel has 25% aromatic hydrocarbons (mainly naphthalenes and alkylbenzenes) and 75% saturated hydrocarbons (mainly paraffin and cycloparaffins).

Gasoline, on the other hand, is a homogeneous blend of small, lightweight hydrocarbons, which has 4 – 12 carbon atoms per molecule. Thus, gasoline comprises paraffin, cycloalkanes, olefins, and aromatics.

Is Diesel Better Than Gas For The Environment

Diesel fuel emits slightly more pollutants than gasoline fuel; however, gasoline delivers higher carbon dioxide emissions, and in general, gasoline pollutes the environment more than diesel. That said, it is safe to say that diesel is better than gas for the environment.

Final Words

This gasoline engine vs diesel engine tries to detail the differences between these two engine types. Gasoline engines run perfectly and efficiently, but for heavy-duty applications such as hauling or towing, it is best to shop a car with a diesel engine – you’d gain more efficiency and power.

Notwithstanding, the major difference between gasoline engines and diesel engines is the combustion procedure. Also, it is a very bad practice to attempt filling diesel in a gasoline engine, or vice versa – you may wreck the engine for such a mistake. Finally, choosing between gasoline and diesel engines is a personal choice.