How does horsepower affect performance?

CT_Tree_Guy · Dec 16, 2005

Lots of great points all around as usual, and a lot of common ground. I think everyone agrees that more torque can be good if you "need" it and have the weight and traction to put it to the ground. And that apart from things like raw lifting ability for picking up indivisible objects, and the weight and size of the attachments you can use, the smaller tractor can do very much the same tasks the larger one can do, given a good low gear and an adequate supply of squirrels, it will just take longer.

I just wanted to defend JCS *[jcmseven]* a bit re: If the two machines listed are equal in weight and have similar tires, they should seem to pull about the same, even though one has more engine power (both torque and horsepower). It sounded to me as if you were just saying that if either engine is able to spin the tires, then the bigger-engine tractor won't have any more effective pulling power than the smaller-engine one, since the coefficient of friction, and amount of power being put to the ground, is exactly the same. I would be pretty much in 100% agreement. In the case of the 18-wheeler example, the VW engine would obviously not be able to spin the tires.

As I said, I think we're all pretty much on the same page. IF you NEED to get things done faster, or have more pull, or not be pushing your tractor as hard at a given pace of work, get more power and more weight.

Lastly, I would just reiterate what I've heard and said many times. When in doubt, get more power, and try to avoid the low end of the power range in a given frame size. And don't forget about lifting capacities, and attachments, for tasks that can't be broken down into smaller "bites". A 402 kg loader can take all the time it wants, but it will never, ever pick up an 853 kg rock or log. And a six-foot backhoe will never dig 9 or 11 feet deep.

3RRL · Dec 16, 2005

jcm...jmc...very cool /forums/images/graemlins/cool.gif

From CT
( Lots of great points all around as usual, and a lot of common ground.)

Everyone...all great points...
Best discussion I've participated in so far.
Thanks

Mickey_Fx · Dec 16, 2005

From an engineering standpoint, torque is the twisting force around a rotating shaft. It is real and can be measured. HP is a mathematical calc that defines a specific amount of work being accomplished in a specific amount of time.

If memory serves me right, 1HP = 33,000ft lbs/per min. or 550ft lbs/sec

You can always gear down a lower powered piece od equipmemt but it will take longer to get a specific amount of work done.

As has been stated previously, what the tractor is capable of doesn't mater if the power can't get coupled to the ground.

CT_Tree_Guy · Dec 16, 2005

I just wanted to defend JCS , and while I'm at it, I'd like to give honorable mention to JFK, FDR, the FBI and the '69 GTO. /forums/images/graemlins/laugh.gif /forums/images/graemlins/tongue.gif

Grr, I was working on two posts at the same time, one to a guy called JCS who is having trouble with his 3,000 sq. ft. concrete floor because the guys who were leveling the pour fell asleep, and it hardened all uneven! Man, what a nightmare!

One more thought on what a smaller tractor might not be able to do: pick up 5' round bales, or pull the baler that makes them. Although it might be kinda cool if you could get a little 18" round baler for a BX to make bite-sized mini-wheats for cows. /forums/images/graemlins/laugh.gif /forums/images/graemlins/cool.gif

JustGary · Dec 16, 2005

"If you only need torque, you can get it by downshifting. You could pull stumps with a squirrel in a rotating cage if you have enough gear reduction, traction, and patience. Two squirrels would pull the stump twice as fast, if they were the of the same ***, straight, and cooperating. You would also need to halve the gear reduction.
" 

In theory, yes, but when you actually attempt this you find that the squirrels pee a poo on everything, which makes the grease behave differently and increases the friction in all of the gear works. At some point their little wheel quits moving because of all the loss they induced by not holding their bladders. They find that they need a bigger wheel and many more friends just to get going again.

I used to have a little Datsun 1200 that I could just shove and then get in and start it by letting out the clutch. I also had an '83 Ford F150 that I couldn't move at all by myself. And they both had only four wheels...

- Just Gary

P.S. Just for fun I used to drive that F150 without using the brakes. It had enough rolling friction that if you kept enough distance in front of you, you could usually slow down fast enough for most any situation by just letting off the gas. It would soon come to a complete stop.

JustGary · Dec 16, 2005

"I was working on two posts at the same time" 

Hmmmm. A two poster, huh? Just two more and you'll become a bed!

CT_Tree_Guy, I like the way you think. We both see the world from odd angles. Keep it up, some of us get the jokes.

By the way, I don't know about any honorable mention for the FBI.

- Just Gary

CT_Tree_Guy · Dec 16, 2005

Keep it up, some of us get the jokes.


Gary, you don't know how reassuring that is. /forums/images/graemlins/smile.gif

As for the FBI - yeah, after I posted that I started thinking about Ruby Ridge, Waco, J. Edgar Hoover (LOVE the dress) and "intelligence failures" ... oh well - how about the NFL instead, or maybe the YMCA? /forums/images/graemlins/smile.gif

flwiii · Dec 16, 2005

I would like to inject a scenario for those who believe more HP is better.

We have 2 engines. One creates 50 foot pounds of torque at 2500 RPM and engine 2 creates 50 foot pounds of torque at 8000 RPM.

Calculating HP:
Engine #1 -- (50 * 2500) / 5252 = 23.80 HP

Engine #2 -- (50 * 8000) / 5252 = 76.16 HP

Which would you rather use to pull your Box Blade?

CT_Tree_Guy · Dec 16, 2005

a scenario for those who believe more HP is better. 

First, I think that anyone who would categorically say that "more HP is better" (leaving aside for the moment the issue of the relevance of HP vs. torque in a typical tractor application) has missed some of the finer points of this thread.

Second, I know of no few if any CUT engines that pull 8 grand, so I'm not sure of the relevance of this example.

Lastly, as to Which would you rather use to pull your Box Blade? I would choose Engine #1, and put Engine #2 on EBay. /forums/images/graemlins/laugh.gif

JustGary · Dec 16, 2005

"Engine #2 -- (50 * 8000) / 5252 = 76.16 HP" 

Now that number is really close to that old Datsun 1200! As I recall, it was 69 HP at 6000 RPM. I had that car over 100 MPH once (on an old airstrip). I don't think I ever got the full 69 HP though. I feel cheated.

My answer is I'd rather have the engine that pulls the box blade best in its particular vehicle. We'd have to know more than just the engine to make a choice.

Why is it that my 28 HP tractor can probably pull my 350 HP pickup all over my yard (I'm not going to try)? Is it horsepower? Is it torque? Magic, perhaps. No, on second thought, just clean living.

- Just Gary

HGM · Dec 16, 2005

Hands down it would be #1

#2 is a gas burner and would either stall or spin the tires when you tried to use the power if it came in at that RPM.... I prefer the idea of a strong lumbering diesel for my tractor.

BTW, if #2 had those numbers, you could never use the TQ and HP. The gearing would be terrible...

I think I understand your point, just cannot say that you can make your decision on HP alone. If your talking tractors, HP is the common rating. TQ and gearing go with it in resonable proportions. Most folks only know HP, the rest is gibberish.. /forums/images/graemlins/grin.gif

How about this one......

Would you rather a horse or elephant to pull your stuck truck out of the mud? /forums/images/graemlins/grin.gif

MMM · Dec 16, 2005

Leaving aside the technical jargon.... and the squirrels, the higher hp tractor can pull more ballast, to do more work. The equal weight, wheel spin comparison is moot point as I imagine the 40h+p weighs quite a bit more than the 20+hp unit. The NH hydro fact is quite interesting, and informative, (good post Tim).

CT_Tree_Guy · Dec 16, 2005

Leaving aside the technical jargon.... and the squirrels 

But I like the squirrels .... /forums/images/graemlins/frown.gif

IslandTractor · Dec 17, 2005

Bigger, more powerful tractors certainly do some things faster but the bigger is better philosophy has its limits and downside too.

One factor the "more horsepower" junkies don't seem to consider is that the higher HP engine will always consume more fuel than the lower horsepower unit even when putting out the same HP. Operating costs and fuel consumption will be higher. So while it is a nice idea to have the reserve HP, you pay for that reserve all the time.

Also, diesels in particular also like to be run at medium to full load, if they are oversized for the usual job (say mowing) then you're also not treating your engine as it should be for optimal life.

MMM · Dec 17, 2005

I don't consider myself a hp junkie, but a realist. Note that I have a baby tractor and it has it's niche. If implement is matched to higher hp tractor, the fuel use and engine load is moot.(except maybe pto genset, spray rig, log splitter) due to more ground being covered under load. Reserve hp isn't sensible to me because I'd rather use it right now if I've got it.

CT_Tree_Guy · Dec 17, 2005

One factor the "more horsepower" junkies don't seem to consider is that the higher HP engine will always consume more fuel than the lower horsepower unit even when putting out the same HP. 

Island:

A) When you were typing this, was I one of the posters you had in mind as being a "horsepower junkie"?

B) If "yes", do you believe that I don't realize that a smaller engine will consume less fuel than a larger one, assuming they are both putting out equal amounts of power?

C) Would you agree that "name-calling" has no place in an intellectual discussion? I have been called an "amsoil lover" for using synthetics. If A = "Yes", then I have now been labeled a "horsepower junkie" for making what I consider to be carefully considered remarks on this subject.

Let's all try to leave the mud-slinging out of these discussions. The "Golden Rule" seems to be falling out of fashion.

BobReeves · Dec 17, 2005

Horsepower junkie's unite /forums/images/graemlins/smile.gif

Went from borrowing the neighbors MF 35 to a Ford 3000, about 10 more HP and I LIKE IT

IslandTractor · Dec 17, 2005

CT,

I meant no harm. I thought horsepower junkies was just a kinda cute term to characterize those who seem to always argue for more Hp. I was not referring to you in particular as several people have put forth the more is better argument in this thread and others.

I assume people do understand the fuel consumption issue but wonder why it rarely comes up in these discussions. I think it's because we all tend to get excited by our tractors ultimate capabilities and often lose site of the more mundane things we do every time we use the machines. Again, I would make the same comment about owning a 3/4 ton pickup if it spends most of the time commuting and only once a year pulls anything close to it's towing capacity. What a waste of fuel. Why don't we size tractors for what is 99% of what they do and then worry about how to accomplish the 1% jobs separately. There seem to be a lot of people who fear a lack of power in tractors. That seems silly as almost all the tractors we use today are more capable than the average machines used just 20-30 years ago on most farms across the country even though most of us (on TBN) seem to use them on personal homesites and not primarily commercially. (CT I know you use yours in business but you are in a minority).

So, I really did not mean to be mud slinging at all and I apologize if it seemed that way. But I do continue to think that horsepower is overrated by many folks on this forum and that there is a real downside to getting a tractor that is bigger than what you really need.

IslandTractor · Dec 17, 2005

( If implement is matched to higher hp tractor, the fuel use and engine load is moot.(except maybe pto genset, spray rig, log splitter) due to more ground being covered under load. )

I agree with your point. However, if you are mowing an acre does that really justify a 15ft bat wing just so you have matched the implement to a high powered tractor. I understand what you are saying but I guess it turns the argument into "proper sizing" of implements for acreage etc.

cisco · Dec 17, 2005

For just pulling (box blade) purposes, there's a much wider range of serviceable tractors than there is for pto powered uses. Sure, a more powerful tractor will be able to move along quicker than a less powerful one that needs to select a lower gear range to match task and torque, given same tire type (e.g. R-4), but sooner or later the relative tires widths and weights of the tractors on those treads will make a task-critical difference, i.e., the less powerful tractor flat out just can't do it, regardless of speed. Much more quickly, in my experience, will the difference in pto show up. Indeed, I've never been in danger of stalling the diesel on my L3410, but I sure have run out of traction despite 4WD, when pulling a fully loaded 6' box blade. Pulling a 6' rotary cutter through thick brush is another matter - I can lug the diesel easily, while my neighbor with a Deere of about 10 more pto hp moves along with that same brush cutter, experiencing only minor fluctuations in diesel rpm when the cutter gets into especially dense stuff.
So, the difference in size/power between those tractors is far more evident with a brush cutter than it is with a box blade.