What are the benefits in performance of a petrol/gasoline car compared to a diesel car and vice versa?



What are the benefits in performance of a petrol/gasoline car compared to a diesel car and vice versa?

In: Engineering

In general, gasoline engines spin faster, and have shallower cylinders, so coupled with a good transmission, this speed can be translated into high speeds for the vehicle.

Diesel engines typically have deeper cylinders and spin slower, and this usually translates into more torque / power, for towing heavier loads.

But, it depends a lot on the design of the engine, and there are many cars that use diesel engines, and they can go as fast as gasoline cars. And there are many gasoline “heavy load” or towing trucks, and they can perform too.

Basically, it’s the job of the transmission to convert the engine’s speed and power to speed or power (or both) “at the wheels”, so there isn’t a clear cut between diesel and gasoline usage.

Diesel engines are *significantly* more efficient than gasoline engines, especially at “steady state”. Due to the way diesel engines function they have a far lower operating speed, usually limited to around 5000RPM on the high side whereas gasoline engines, depending on technology, can often rev to 7000RPM or higher.

Diesel engines often are turbocharged which allows for a fast onset of torque that performs through the entire useful engine speed. Gasoline engines benefit from turbocharging as well but they don’t typically make max power until higher on their RPM range (engine speed).

Due to the diesel combustion cycle their engines typically produce far more torque than a similarly sized gasoline engines.

Back to what I said about “steady state”; diesel engines can perform in their upper RPM range making maximum power essentially forever. Gasoline engines cannot do this because they can’t run at those operating speeds to produce maximum power for any significant amount of time. This comes back around to the efficiency. Most of the efficiency difference between the two engine types is lost to heat in a gasoline engine; they essentially cook themselves to death.

Most stuff that runs constantly like industrial generators, heavy equipment hydraulic pumps, etc take advantage of this increase in efficiency at steady state.

A gas engine is better for short bursts, but diesel has to be running a long time before its better efficiency balances out the slow start.
You could think of it like a distance runner vs a sprinter. They both run and get from point A to B, but after a certain distance, one will outperform the other.