Torque and power produced in an engine

In summary: With this in mind, my guess would be that the reason power varies with rpm is that it is a function of torque over time.
  • #1
mzha109
11
0

Homework Statement


Why does an IC engine generate about the same maximum torque over a range of engine speeds but the maximum power at only one speed?


Homework Equations


None.


The Attempt at a Solution


For max power, the best I can come up with is that since torque does not drop as fast as rpm is increasing, max power occurs after peak torque.

As for why max torque can occur over a range of engine rpm, I have no clue.
 
Physics news on Phys.org
  • #2
I'm no expert, but with a bit of hand waving I would say that the torque is more or less directly related to the "average" pressure after ignition in each cylinder and since this pressure is more or less the same at the same point in the stroke-cycle for a cylinder for a wide range of rpm's, the torque must also be more or less the same.

Your explanation for maximum power sounds correct.

I hope a late answer is better than no answer at all. If nothing else, its an interesting question.
 
  • #3
Thanks. The thing is, there's no mention of this in our coursebook, and because our lecturers are old men, they don't check their emails. So you'll forgive me if I don't take your answer unless you're absolutely certain

----EDIT----

The lecturer just released the answers. You were right after all. My apologies for ever doubting you.
 
Last edited:
  • #4
Being skeptical about unsupported claims is a hallmark of good science, so no need for apologies, my friend.

Even though your professor released their answers, to support my claim I may add that I did manage to find a diagram labeled "Effect of engine speed on cylinder pressure with variable optimum ignition timing" in [1] depicting cylinder pressure vs crank-angle position for various engine speeds that show the peak pressure only drops very slowly as speed increases. The "variable optimum ignition timing" here means that ignition is started earlier on the crank-angle position for higher speeds to compensate for flame propagation time, so for a very simple internal combustion engines without such compensations the torque curve may not be as flat as it is for a modern or more advanced engine.

[1] Advance Engine Technology, Heinz Heisler, Butterworth-Heinemann, 1995.
 
  • #5
Ah thankyou.
 
  • #6
Friend what I think is torque developed depends on amount of air and fuel gets into the engine cylenders. This is almost equal for a range of rpm. So max. torque is defined for a range of rpm
 
  • #7
Horsepower is a function of torque over time. Put simply, HP = Torque x RPM / 5252. (Google will provide numerous descriptions of the derivation.)
 

What is torque?

Torque is a measure of the rotational force generated by an engine. It is typically measured in pound-feet or Newton-meters and represents the amount of force that an engine can exert to rotate an object.

What is power?

Power is the rate at which work is done or energy is transferred. In the context of an engine, it is the amount of work that can be done per unit of time. It is typically measured in horsepower or watts.

How are torque and power related?

Torque and power are closely related in an engine. Torque is the force that produces rotation, while power is the rate at which torque is produced. In other words, an engine with a higher torque output will typically have a higher power output as well.

What factors affect torque and power in an engine?

The torque and power produced by an engine can be affected by a variety of factors, including the engine's design, displacement, compression ratio, and fuel type. Additionally, factors such as air intake, exhaust flow, and engine tuning can also impact torque and power.

How is torque and power measured in an engine?

Torque and power can be measured using a dynamometer, which is a device that applies a load to the engine and measures its output. In a laboratory setting, torque can also be measured using a torque transducer, which converts the engine's torque into an electrical signal that can be measured.

Similar threads

  • Engineering and Comp Sci Homework Help
Replies
1
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
1K
  • Mechanical Engineering
Replies
18
Views
5K
  • Introductory Physics Homework Help
Replies
8
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
13
Views
1K
  • Electrical Engineering
Replies
9
Views
610
  • Engineering and Comp Sci Homework Help
Replies
1
Views
3K
  • Mechanical Engineering
Replies
19
Views
669
Back
Top