kubota vs. kioti

[LD1]

So, a "horsepower guy" says 8.5 mph. Anyone from the "torque camp" want to give their answer?

Are you looking for more than 1 answer?

 

[tomato coupe]

Are you looking for more than 1 answer?

Implicit in your answer is that the tractor is operating at 2700 RPM, since you are using 50 HP in your calculation. High torque occurs at 1600 RPM, however, so I am interested if someone in the "torque camp" calculates a different max speed by operating the engine at the torque peak.

 

[SPYDERLK]

You know that you will not get max speed at torque peak. Max is only available by gearing to correspond with power peak.... unless a real world transmission gets lossy at some ratios.

 

[tomato coupe]

You know that you will not get max speed at torque peak. Max is only available by gearing to correspond with power peak.... unless a real world transmission gets lossy at some ratios.

Your assertion is essentially what LD1 has stated in many of his posts, i.e. "engine horsepower is more important than engine torque" in regards to maximizing the work done by a tractor. I think several posters will disagree with you, and they will argue that high torque is more important. I would simply like to hear what their answer to the problem is.

On a more general note, the problem I posed was chosen for a few reasons:

1. It is pretty simple to solve.
2. It mimics the model used to define horsepower, where a horse lifts a certain amount of weight a certain height in a set amount of time.
3. With a few basic assumptions, the theoretical answer can closely match reality.
4. The horsepower and torque curves are from a real engine -- they are not peak values pulled out of thin air.

Cheers

 

[LD1]

You know you won't get anyone in the " torque" camp to answer once they put pen to pad. But you will likely get lots of excuses, not real world, put a 15k rpm bike engine in a tractor answers.

 

[LD1]

I've got one more question for the torque camp...

What is better. An engine that can make 1.6 million ft-lbs of power in one minute, or one that can make 2.6 million ft-lbs. (Since you guys like torque so much)

 

[TomSeller]

Divide that by the tractors weight, and you get the vertical distance it can lift itself in 1 hr measured in ft. .

Kubotas do well in this regard.

 

[dragoneggs]

Your assertion is essentially what LD1 has stated in many of his posts, i.e. "engine horsepower is more important than engine torque" in regards to maximizing the work done by a tractor. I think several posters will disagree with you, and they will argue that high torque is more important. I would simply like to hear what their answer to the problem is.

On a more general note, the problem I posed was chosen for a few reasons:

1. It is pretty simple to solve.
2. It mimics the model used to define horsepower, where a horse lifts a certain amount of weight a certain height in a set amount of time.
3. With a few basic assumptions, the theoretical answer can closely match reality.
4. The horsepower and torque curves are from a real engine -- they are not peak values pulled out of thin air.

Cheers

This is getting good! Thanks Mr. Tomato. As a mechanical engineer, I am truly enjoying this thread regardless of how off track it is going.

 

[LD1]

Perhaps the title should be changed to HP vs TQ. Since I think that's what the majority of it is. Wouldn't surprise be a bit if it reached 500 posts.

 

[paulfun9]

Add to your problem what happens when you are pushing the machine by hauling more weight than the machine can carry at peak RPM such as when you are stuck down gearing because the engine cant hold the peak RPM going up the hill.

Math is fun but when real world problems are added the formula will be different and the outcome wont always be so obvious.



.

 

[tomato coupe]

Add to your problem what happens when you are pushing the machine by hauling more weight than the machine can carry at peak RPM such as when you are stuck down gearing because the engine cant hold the peak RPM going up the hill.

Math is fun but when real world problems are added the formula will be different and the outcome wont always be so obvious.
.

Actually, the equations still apply. In the situation you are describing, you just need to add the extra mass. You can make a similar correction if the angle of the incline changes.

 

[LD1]

Yep. All calculations still apply. You can change any variable you want. Slope angle, HP, weight, etc.

Here is some more to think on.
In a typical real-world dyno, rpm(speed) will fall off quicker than HP. IE: if peak power is @ 3000rpm, at 1500 you will likely have more than half of what the peak was. Maybe 60% or so.

Why do I mention that? Simple. If you have ever driven a tractor on the road, in high gear and went up a hill. Did you notice that you might have dropped 500 rpm and then it quit falling off? That's because the speed decreases at a faster rate than power. And you reach an equilibrium point. If you don't, and rpm keeps falling, you downshift.

 

[SPYDERLK]

I've got one more question for the torque camp...

What is better. An engine that can make 1.6 million ft-lbs of >>>power<<< in one minute, or one that can make 2.6 million ft-lbs. (Since you guys like torque so much)

Do you mean energy?

 

[LD1]

Do you mean energy?

Uh, yea. HArd to keep things straight late at night:laughing:

Power, energy, force, work, etc were all hard terms for me to keep straight. Since most people (wrongly) unse them interchangeably.

The end result of the energy and time is power (as in horsepower) which is what I was going for...

 

[sd455dan]

View attachment 372140 View attachment 372141

Here's an interesting comparison- the Kubota graph posted and one from an older lower revving and larger displacement tractor engine
two tractor engines with equal peak rated horsepower- which one has more average horsepower and will do more real world work when run at non peak rpm... as in pulling a plow or other heavy implement from a dead stop in a geared transmission tractor :stirthepot:

I believe a higher torque / lower peak rpm engine is better suited to tractor work.

attachment problem?

 

[TSO]

View attachment 372140 View attachment 372141

Here's an interesting comparison- the Kubota graph posted and one from an older lower revving and larger displacement tractor engine
two tractor engines with equal peak rated horsepower- which one has more average horsepower and will do more real world work when run at non peak rpm... as in pulling a plow or other heavy implement from a dead stop in a geared transmission tractor :stirthepot:

I believe a higher torque / lower peak rpm engine is better suited to tractor work.

I avoid major math because it doesn't suit me ... but just out of curiousity, I don't suppose you'd be able to find & post the graph for my engine, or to see how it rates here in this test???

Iseki E4CG, 4cyl, 2.2L, 134.05ci, 21.8:1 compression, Bore/Stroke=87mm/92.4mm, Max Torque=103.6 ft/lb (or 140Nm) @ 1500rpm, torque @ 2600 rpm = 95.1 ft/lb (or 128.9Nm), torque rise= 9%, Engine HP (gross) = 47.1 (or 35.1kW) @ 2600rpm.

Thanks.

 

[sd455dan]

Sorry TSO i don't have a graph for the Iseki

I should say that i don't believe there would be much of an advantage for the engine I posted when used with a Hydrastatic drive tractor- when the tractor is operated at rated speed/power all the time.

 

[sawtooth]

You know I was thinking. I have a 1953 Ford Golden Jubilee and if I'm not mistaken it has 30-32 pto hp. Engine was rebuilt and is in very good shape. Funny thing is that it barely runs a 5 ft Hog with 40hp gearbox in tall thick grass while being only in 1st gear. Now my Ford 2810 with 34pto HP will run the daylights out of my heavier 6' hog that has a 110hp gearbox running in the same heavy grass. So it this due to the higher torque values being generated via the Diesel engine or is there something else I'm missing?

 

[k0ua]

You know I was thinking. I have a 1953 Ford Golden Jubilee and if I'm not mistaken it has 30-32 pto hp. Engine was rebuilt and is in very good shape. Funny thing is that it barely runs a 5 ft Hog with 40hp gearbox in tall thick grass while being only in 1st gear. Now my Ford 2810 with 34pto HP will run the daylights out of my heavier 6' hog that has a 110hp gearbox running in the same heavy grass. So it this due to the higher torque values being generated via the Diesel engine or is there something else I'm missing?

One thing that would come immediately to mind, is you are not testing with the exact same bush hog.. How dull are the blades of one vs the other?.. In other words, you have proven nothing with your observations, as you are not using the same bush hog.. for instance did you put the 6ft hog on the lower PTO horsepower tractor? How do you know it wont do better.? Now it is all possible you are 100% right in your assesment, but until some more testing is done, you cannot know that for sure, an neither can any of us.

 

[LD1]

The fact that it us a diesel has nothing to do with it. The 2810 is only 32 PTO HP vs 30 for the naa. The NCAA has more torque though. 110@ 1400rpm vs the 2810 having 101ft-lbs also at 1400.

I agree with James that it isn't a good comparison. You need the same cutter on both. But its funny how you said the one with more power (but less torque) pulls the cutter better.