Skip the auto shop - Our mechanics make house calls

Q: How Are Diesel and Gasoline Engines Different?

asked by on

How are diesel and gasoline engines different?

A: There are two main differences between gaso...

There are two main differences between gasoline and diesel engines. Gasoline engines use gasoline for fuel and spark ignition to ignite the fuel. Diesel engines use diesel fuel and compression for ignition to ignite the fuel. There are also many minor differences between how the two engines work.

The gasoline engine uses lighter duty engine components since the gasoline engine usually has lower compression and will produce less horsepower and torque. The gasoline engine has an electronic ignition and spark control. Gasoline engines use a throttle body with a throttle cable or electronic actuator to control the opening of the throttle plates that control the air going into the engine. The fuel is injected into the intake air flow on most engines and some have a direct injection system to inject high pressure into the cylinder directly. Once the mixture is compressed, it is ignited using a spark plug. The result is a power stroke.

A diesel engine uses heavier duty components due to the higher compression and heat the engine produces. The air goes into the intake through a diaphragm type spring valve plate in the intake and engine speed is controlled by injected amounts of fuel via an injection pump. The diesel fuel is injected into the cylinder head small cup area and the compression of the engine ignites the fuel and air in the cylinder when the piston reaches top dead center. Diesel fuel will produce more power than gasoline and most diesel engines will produce more torque than a same size gas engine will. The diesel engine will use glow plugs to preheat the cylinder head cup to help ignite the fuel in cold temperatures, which is a problem that a gas engine does not have in most temperatures. Diesel engines will weigh almost twice as a gasoline engine with the same displacement. Diesel engines are designed for heavy duty work loads and in most cases will outlast a gasoline motor.

When it comes to choosing a gasoline or a diesel motor it should come down to what kind of work the engine will be doing, rather than personal preferences. A gasoline motor runs quieter and smoother, while a diesel engine is noisy and runs smoother above idle. A diesel engine is more common in trucks and large cars where they carry heavier loads better than gasoline engines for long term use.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car sat for a year now it keeps dying, so what could be wrong?

If the vehicle sat for a year with a partially filled tank of gasoline, the gasoline has oxidized and components of the fuel have separated out and turned to varnish. If that is the case, the fuel injectors are likely...

Q: How do I read the fuel gauge?

The fuel gauge is located on the instrument panel, inside the speedometer. This gauge tells you how full your fuel tank is. When the needle points all the way to the right of the gauge, your tank is virtually full....

Q: Vehicle bucks while driving

It's not likely that servicing your transmission will fix your problem. Without experiencing the problem firsthand, it's difficult to say if what you have is an engine or transmission problem. Obviously, internal transmission issues can result in a harsh downshift...

Related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...