why a diesel engine is so much more powerful than an gas engine.
In: Engineering
Several reasons – diesel fuel has more stored energy than gasoline. It combusts much sooner than gasoline, so it spends more time pushing pistons. The engines are built to compress fuel/air at a higher ratio; that plus longer stroke length for pistons means that diesel fuel spends more time moving mechanical parts and those mechanical parts are designed to provide more power
It isn’t. An equal size diesel and petrol engine will produce different horsepower, and the gasoline engine will make more of it. The difference is that a large diesel engine making the same amount of horsepower as a gas engine will make loads more torque and consume less fuel. This is why trucks and tractor trailers use large diesel engines.
Torque is useful because it allows towing extremely heavy loads.
TL:DR: Horsepower is how fast you hit the wall, torque is how far you push the wall.
Apologies for the formatting, I’m on mobile.
It mostly comes down to compression ratio differences. The much higher compression of diesel engines causes combustion to go faster and hotter, which results in higher thermodynamic efficiency and more power.
There are smaller factors, such as diesel fuel having higher energy density and diesel engines not suffering pumping losses.
The torque differences are a result of different geometry necessitated by higher compression ratios. It’s easier to raise compression ratios by lengthening the stroke length, which has the side effect of creating an engine that has greater mechanical advantage. The down side of longer stroke length is that the piston will have higher average velocity; this places a limit on engine RPM that gasoline engines usually don’t have (gasoline engines usually are limited by the valve train).
So, this is partly right. A diesel engine typically produces far more torque (twisting power) than a gasoline engine because diesel is more dense than gasoline (it is literally heavier) so each explosion creates more power. Thing is, the motor doesn’t turn very fast. As a result almost all diesel engines have some sort of forced induction, like a turbocharger which help with horespower tremendously. Horsepower is torque times engine RPM times 5252. So if you get all of your torque at 2,000 RPM, you have a lot more power than a gasoline engine at the same RPM but the motor will not be able to rev as high. The turbo helps with that but you will still notice diesels have a lower red-line than gasoline engines.
Diesel has more torque (twisting force) but less overall power.
If you have a two 2.0 litre engines one petrol and one diesel.
The petrol one will produce more overall horse power but less torque, let’s say 250hp and 300Nm of torque.
The diesel one will make more torque which gives you more low end power. Let’s say the diesel engine makes 190hp and 450Nm of torque.
So when you drive them both the petrol one will rev out higher and will produce more power but it comes later up the rev range.
When driving the diesel one it will accelerate harder lower down in the rev range but it won’t rev as high and when you get higher into the revs it loses its grunt more than the petrol.
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