Skip to content

What’s the Difference Between Diesel and Gas Engines?

What’s the Difference Between Diesel and Gas Engines_

When it is time to purchase a vehicle, you have the option of purchasing a gasoline or diesel engine. What you may not know is what the difference is between the two engines. The main difference between he two is in the timing of the fuel delivery system which allows diesel engines to operate more efficiently than gasoline engines. However, there are other differences that can also be important when you are looking at purchasing a new vehicle.


Comparing Diesel and Gasoline Combustion Cycles

Both diesel and gasoline engines have compression, exhaust, ignition and intake strokes in their combustion cycles. Both are also designed to convert fuel into mechanical energy once it is ignited. The intake is the first downward stroke of the piston. Both air and fuel enter the piston during the intake stage in a gasoline engine. The mixture then moves to the carburetor and mixed long before it gets to the chamber. If the engine has a port injected system, the fuel is injected just outside of the piston before entry.

In a diesel engine, the only thing entering the piston during intake is air. When the piston moves upward, it compresses the contents of the cylinder. In a gasoline engine, the compression ratios are lower than in diesel engines. During ignition, the compressed air and fuel is ignited in a gasoline engine while diesel engines use direct fuel injection at the beginning of the ignition stroke. Both the gasoline and diesel engine operate the same during the exhaust stroke of the piston.

Fuel Efficiency and Higher Compression

Gasoline engines use lower compression to prevent spontaneous ignition of fuel and air as it creates excessive heat which can lead to engine knocking. Gasoline engines have a compression ratio of between 8:1 ad 12:1 while diesel engines have a compression ratio between 14:1 and 25:1. This translates to more power available to do the work of the engine while operating in a more fuel-efficient manner. This, combined with the higher amount of energy stored in diesel fuel, contributes to the low mileage diesel engines are known to provide.

Cold Starting Issues

Because compressed air within diesel engines must reach a higher temperature than gasoline engines during startup, diesel engines often need assistance in starting when the engine is cold. Most people use glow plugs, or wires that are electronically heated, to heat the interior of the cylinders enough to get the engine started. In newer diesel engines, computer controls are able to delay the timing of fuel injection when the weather is cold, allowing the engine to heat without the need for glow plugs.

If you have a diesel or gasoline engine and you’ve been involved in a collision, we are here to help you get your car back on the road. Contact us today to schedule an appointment by giving us a call or fill out the simple form online.

Contact us

Skip to content