Why do diesel engines produce less power than gasoline engines?

In summary: This extra weight and the associated increase in inertia can also impact the diesel's ability to rev quickly and deliver maximum power.I understand, thank you.
  • #1
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Hello all;

I have been thinking about this for some time and searching through the internet for it but couldn't get a satisfactory answer for it, so i decided to ask this to you. Here is my question:

If diesel fuel has more energy in it than gasoline does and if diesel engines are more efficient than gasoline engines, why do diesel engines create less power? For example, a car with a 1.4 diesel engine cannot exceed 130 km/h on a straight road but a car with gasoline engine with the same properties (except it's a gasoline engine:) ) can go up to 150 km/h. As far as i know, obstacles to speed on a straight road is just the air friction and that means gasoline engines produce more power (P=F.V), don't they?

Im stuck here and I will appreciate any help from you, thank you for your interest.
 
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  • #2
Gasoline engines tend to run at higher RPMs than diesel engines. For running a car at high speed, an engine turning at high RPM is a necessary condition, assuming sufficient power is available to overcome drag.

As has been discussed in these forums before, due to the nature of diesel combustion, there is an upper limit to engine RPM beyond which there is insufficient time available for complete combustion of the diesel fuel to occur.

It's not that diesel engines create less power than gasoline engines, it can be viewed that they create the same power with less fuel. Most diesels are designed for economy of operation, not top end performance.
 
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  • #3
OK, i understand thank you very much.
 
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  • #5
kalamar20 said:
Hello all;

I have been thinking about this for some time and searching through the internet for it but couldn't get a satisfactory answer for it, so i decided to ask this to you. Here is my question:

If diesel fuel has more energy in it than gasoline does and if diesel engines are more efficient than gasoline engines, why do diesel engines create less power? For example, a car with a 1.4 diesel engine cannot exceed 130 km/h on a straight road but a car with gasoline engine with the same properties (except it's a gasoline engine:) ) can go up to 150 km/h. As far as i know, obstacles to speed on a straight road is just the air friction and that means gasoline engines produce more power (P=F.V), don't they?

Im stuck here and I will appreciate any help from you, thank you for your interest.
Not knowing many of the specifics of your example, I can't really give an explanation regarding it. I can say that, in general, diesel engines DO have more horsepower and torque than a gasoline engine with the same displacement. Drop-for-drop, diesel fuel has much greater potential energy than gasoline. In modern diesel engines, they are considerably efficient due to the use of turbo chargers and intercoolers.
Noteworthy: the vehicles you are using as your example very likely have a factory-set limit on the revolutions/minute that the engines can output... and/or the speeds you mentioned just happen to be the mechanical limit of the engine.
 
  • #6
As high speed diesels have evolved their dynamic performance has approached that of gasoline engines.
Some very significant steps in the evolution so far have been indirect injection, turbo chargers and common rail electronic injection.

Diesels may have a compression ratio of 20:1 which requires heavier construction than a gasoline fuelled SI engine with a maximum compression ratio closer to 10:1.
 

1. What is diesel engine horsepower?

Diesel engine horsepower refers to the amount of power that a diesel engine can produce. It is a unit of measurement that indicates the engine's ability to do work.

2. How is diesel engine horsepower measured?

Diesel engine horsepower is typically measured using a dynamometer, which is a device that measures torque and rotational speed. The horsepower is then calculated using the formula: horsepower = (torque × rpm) / 5,252.

3. What factors affect diesel engine horsepower?

There are several factors that can affect diesel engine horsepower, including the engine's size, design, and fuel system. Other factors include the air intake and exhaust system, as well as the engine's temperature and altitude.

4. Is higher horsepower always better?

Not necessarily. While higher horsepower can provide more power and torque, it can also lead to increased fuel consumption and emissions. It is important to consider the intended use of the engine and find a balance between power and efficiency.

5. Can diesel engine horsepower be increased?

Yes, there are various ways to increase diesel engine horsepower, such as modifying the fuel injection system, adding a turbocharger or supercharger, or upgrading the engine's components. However, it is important to consult a professional and make sure the modifications are done safely and legally.

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