Does HP matter?

[LD1]

Well, against my better judgment, lets break it down one more time.

If torque is the same, work that CAN be done is the same.

You disagree with this.

Torque is defined as twisting force. If two engines have the same torque, they have the same amount f twisting force.

Work that needs done requires twisting force to accomplish. If the two engines are able to apply the SAME twisting force the work they are "able" to do is the same. (regardless of how fast they can apply that twisting force)

If you have to accomplish work that needs 100ft lbs of torque to accomplish, and you have a 99ft lb engine, it simply isnt going to get it done regardless of weather it has 10hp or 100hp.

Now what of that do you disagree with and why??

If you can gear the the higher HP machine to do more work, you can ALSO gear the lower HP machine to do just as much work. (IF the engine starts off with the same torque)

As in the example above, say you have work that needs done and requires 100ft lbs of torque. and you have 2 engines with 99ft-lbs. One with 10hp and the other with 100. Neither will do the work. But If you add a gearbox to boost the torque, now they will BOTH do the work. But the 100hp engine will simply be 10 times faster.

It dont matter HOW much torque is required to do the work, you can always add gearboxes to get it done. You can add a 100:1 gearbox to the 10hp engine just the same as the 100 hp engine and the end result will still be the same torque.

So when I say that you can gear both the high AND low HP engines to accomplish the work at hand, you diagreed. Care to elaborate as to why?

If torque is the same, work that CAN be done is the same.

You can ALWAYS gain torque by gearing. Thats no secret. But HP remains constant (minus a little frictional losses).

If you can gear the the higher HP machine to do more work, you can ALSO gear the lower HP machine to do just as much work. (IF the engine starts off with the same torque)

And the RPM's have nothing to do with the time element of HP. All the RPM's mean is THAT is the point that they measured the HP. Two totally different things. RPM is just the point at which the measurment is taken.

You can take a 100hp engine with 100ft lbs of torque, and then you can take a 20hp engine with the SAME 100ft-lbs, and the work they are ABLE to do is exactally the same. The 100hp engine will just be quicker is all.

And the RPM's have nothing to do with the time element of HP. All the RPM's mean is THAT is the point that they measured the HP. Two totally different things. RPM is just the point at which the measurment is taken.

This was in response to another poster. They were saying that a figure like "32hp @ 2500rpm", that the 2500rpm was already the "time element" or HP. But it is simply the point at which the measurement was taken. Whats wrong with that? I suppose that since torque is listed as something like "80ft-lbs @ 1600rpm", that torque also has a time element???

You can take a 100hp engine with 100ft lbs of torque, and then you can take a 20hp engine with the SAME 100ft-lbs, and the work they are ABLE to do is exactally the same. The 100hp engine will just be quicker is all.

Kinda reverts back to my example in the second part of this post. I dont see why you think it is wrong?

Same torque = same work that "CAN" be accomplished.

Added HP just makes it get accomplished faster.

 

[DarkBlack]

Against my better judgement, Apologize for your previous insults, and I'll take the time to explain.

 

[jenkinsph]

LD1 and DarkBlack,

You guys need to speed up your responses:licking: I ain't got al night.:laughing:

 

[Diamondpilot]

For me it weight is important. For example my uncle has a 35HP JD and my 28HP Jinma weighs nearly 2000# more and will just flat out pull it. Yes, he has more PTO HP but he was flat amazed when I brought my tractor over to his house to move some dirt and gravel with him. He now calls me for help pushing our bigger snows.

Chris

 

[jejeosborne]

... How about HP will always be half the Torque at 2626. He'll be more comfortable with that.

Very true. My point was that the formula cannot be disputed. Torque at working rpm is all that matters. My weed eater makes a lot of HP but very little torque. I would hate to gear that motor down and put it in a tractor though and have to listen to it scream. I had a similar discussion a while back about the ram hemi making more HP than the cummins diesel but the cummins makes a lot more torque. The hemi could do the same work faster but only if you can maintain that constant peak HP rpm(5600 rpms). No thanks.

 

[LD1]

Against my better judgement, Apologize for your previous insults, and I'll take the time to explain.

I would really like to. But you have given me no reason to. Your last two posts since I allegedly insulted you kinda prove that.

You have yet to contribute anything useful. You are just standing in the back of the room, and occasionally saying "your wrong" with absolutely nothing to go with it. I dont even know why I bothered responding to you in the first place:mur: And I dont know why you are even posting in the thread. Saying "your wrong" does nothing to help out any other TBN members, and when thats ALL you say, in turns into confrontation and childish arguing because that is called trolling. You are just trolling along and looking for an argument or debate. IF you werent, you would have explained yourself the first time. I tried. But it seems you dont want to have an grown up discussion and insist on keeping it childish.

I'm done

Moving on..........

 

[john_bud]

I agree and would add another non-technical comment, torque will get you there, HP keeps you there. What I mean is torque is the power to accelerate, etc...but HP allows you to maintain the work / speed etc...

That is why in the automotive world Torque is all important for 0-60 times but HP is critical for Top Speed numbers.

So yes it does matter, (but only if you actually will use those extra horses).

Do you have that backwards? You can pretty accurately calculate HP from 1/4 mile times, you can't do that to find torque.
Or is that not right? (seriously, I'm not sure!)

 

[EE_Bota]

Honestly, I don't find HP vs Torque thinking very meaningful in the vacuum of not knowing the gearbox characteristics and the users desired performance.

If a person says something I disagree with, frequently I find it is best to just say what I believe is true in an completely independent post. In Friendly Politics, we almost always quote the other person, highlight what we are commenting on, and then tell them they are wrong, and exactly why they are wrong. It's little wonder that approach is reserved for a semi-private forum.

In most other forums, many of us do have a desire to have correct information put forward to avoid misleading our members. That function can be adequately served by individuals writing their own separate posts stating the truth about matters. That approach helps to avoid the boring and annoying process of unwinding previous posts, re-quoting them, and then debating the context, and even the meaning of words.

From a strict physics point of view, many of the posts in this thread were somewhat unfortunate because many of the words have both strict physics meanings and common usage meanings. It was pretty clear to me that many of you were mostly meaning the common usage definition. But really, who cares. If anyone has any doubts they have gotten the correct idea, speak up and I'm sure correct assertions will be made to clear up any misunderstanding. But I do believe that most of you did and do understand.

It should be remembered that unlike most cars, most tractors tend to have a governor that is attempting to hold the engine speed the user has set. That governor will provide more or less fuel to try the keep the engine at the set speed. So in most cases, a tractor engine will be somewhat of a torque exercise rather than a HP exercise (the designer already made your gearbox decision.) My car has a five speed, and I go through all the gears during each change of the light. This is a totally different usage, and HP is a big part of it. But when I am in 5th cruising down the highway, torque is a big deal since I really just want to hold my road speed, much like a tractor does nearly all it's life...it mostly it trying to hold your set speed against varying load conditions.

 

[cartod]

For me it weight is important. For example my uncle has a 35HP JD and my 28HP Jinma weighs nearly 2000# more and will just flat out pull it. Yes, he has more PTO HP but he was flat amazed when I brought my tractor over to his house to move some dirt and gravel with him. He now calls me for help pushing our bigger snows.

Chris

Without weight, you can have no traction. I guess that is for another class. :confused2:

 

[jejeosborne]

Do you have that backwards? You can pretty accurately calculate HP from 1/4 mile times, you can't do that to find torque.
Or is that not right? (seriously, I'm not sure!)

One thing to remember is that acceleration follows the torque curve and I think that is what was meant. You are correct with the common calculation from the strip. They make assumptions on aerodynamics and gear losses etc and now you enter the time element which is the key to HP.