What is the difference between a diesel engine and a gasoline engine?
Since gasoline has a high ignition point, it must pass through the spark plug to ignite after the engine piston is compressed.
Diesel engines do not require spark plugs. They rely on the temperature rise after gas compression to directly cause spontaneous combustion of diesel fuel.
This compression ignition effect also gives diesel engines many advantages. For example, it does not require an ignition system and has a lower failure rate. The compression ignition method allows the compression ratio to be very high. The compression ratio of an ordinary gasoline engine is 13:1, which is already very high. , but a diesel engine can easily do 17:1
By using a longer piston connecting rod, the piston stroke is increased, the engine torque is greatly improved, and the fuel economy of the diesel engine is even better with the same displacement.
Different engine speeds
Gasoline engines can pre-mix the gas, which means mixing gasoline and air before injecting it into the cylinder, or direct injection into the cylinder, using a high-pressure injector to atomize the gasoline and compress it while mixing in the cylinder.
When the engine piston is at top dead center, it is ignited by the spark plug. In short, the gasoline and air are mixed first and then burned.
However, diesel has high viscosity and cannot be effectively mixed with air, so the diesel machine first sucks in air, then compresses and heats the air, and then injects diesel when the piston is close to top dead center, using the high-temperature air to ignite the diesel.
The entire combustion process is also divided into a pre-combustion period, a fast combustion period, a slow combustion period and a post-combustion period. This method has an obvious disadvantage, which is that it requires a longer combustion time. The increase in the piston stroke mentioned earlier is also for this purpose.
Therefore, the speed of the diesel engine cannot be set too high. Too high a speed will not only prevent the diesel from being completely burned and emit black smoke like crazy, but also cause torque attenuation.
The speed of diesel versions of many cars is also much lower than that of gasoline versions.
What happens if you add fuel by mistake?
If diesel is mistakenly added to a gasoline engine, the diesel will already achieve compression ignition before the spark plug ignites, and the engine will produce obvious knocking.
And if a diesel engine is filled with gasoline, the engine will not be able to work at all because the temperature generated by compression is not enough to ignite the fuel-gas mixture.
Diesel engines “can’t do the job” of gasoline engines
Diesel engines are fuel-efficient, durable and have powerful torque, so they are very popular in Europe. Diesel vehicles account for more than 50% in Europe, and 80% of taxis are diesel vehicles. However, diesel vehicles are difficult to popularize in our country.
The main reasons are nothing more than mismatched diesel quality, relatively loud vibration and noise, and many people are conflicted from the bottom of their hearts. Even though diesel engine technology is becoming more and more advanced and is very close to gasoline engines, it is still difficult to achieve large-scale application in China.