Torque vs HP???

[leeave96 487]

Torque vs HP.

I'm tooling along with the 314-8, enjoying some badly needed seat time/therapy while mowing grass and I roll into at tall patch of grass. From 3600 RPMs, the engine falls to 3200 RPMs, the engine grunts and bull dozes through, obliterating the tall grass and then back to a smooth 3600 RPMs.

What saved the day, torque or HP?

Thanks!

Bill

Edited November 6, 2013 by leeave96

[Terry M-(Moderator) 2,126]

in this case maybe the governor should get the credit..along with horsepower, would be my guess…...

[WH nut 553]

Torque

[KATO 115]

Im gonna have to agree with Terry as most small engines torque peaks are below 3000 rpm

and some below 2500 rpm according to what ive seen.

[Hodge71 663]

I'm thinking torque. It is the ability to do work and is measured in lb-ft…. Hp is just a mathematical equation that uses torque's its base over time and really isn't an accurate representation of its ability to accomplish task. The equation is lb-ft /time ( Pound feet divided by time). One horsepower equals 33,000 lb-ft/minute so therefore HP= lb/ft x rpm x 6.283/33,000….(torque x rpm x 2pi divided by 33,000. 

 

Think of it this way…. high torque means it can do more work…like bodybuilder lets say. Horsepower is closer representation of how quick it can do something…like a sprinter. You have a body builder and a sprinter run 100 yards and time them…the sprinter will blow the body builder away but if you put 100 pounds of weight on their backs and have them run the 100 the body builder will not notice that much of a difference and do the 100 in a similar time, while the sprinter will be much slower as he is built to be quick but not powerful under great loads….

 

Great now I'm confused     

[boovuc 1,090]

Wow Hodge! That is a great analogy!

"You have a body builder and a sprinter run 100 yards and time them…the sprinter will blow the body builder away but if you put 100 pounds of weight on their backs and have them run the 100 the body builder will not notice that much of a difference and do the 100 in a similar time, while the sprinter will be much slower as he is built to be quick but not powerful under great loads."

 

It beats the formulas and equations of the two measured forces.

[Coadster32 793]

I like this analogy too.

[RMCIII 838]

There are always rules to that exception of the Bodybuilder analogy.... Unless the Bodybuilder is also a sprinter... And that, my friends, can be done....Now, add to the original question, since Hodge has given the explanation... What "Type" or "Measurement" of Horsepower would this relate to that Bill's tractor was using? Don't CHEAT!!!!!

[Save Old Iron 1,563]

except torque is a ROTARY (twisting) motion, not like running in a straight line.

 

given your example of a 100 pound ballast on both subjects, if the bodybuilder gets the same work accomplished in half the time - he has twice the "horsepower" of the sprinter.

 

Both are required to do the exact same work and the higher HP rating will get the work done in less time.

[leeave96 487]

OK - here's what I think I've figured out on the hp vs torque deal.

 

Forgive me, don't mean to offend, but this is how I explain it to my Boys and in doing so it helps me understand too.

 

HP is a measure of work over time, so some motion must be involved, else zero hp is present.

 

Torque is the tool hp uses to get the work done - think torque wrench on a bolt.

 

So my Great Grandfather, James had a farm and never had any other thing than horses to farm with.

 

So he's got some kind of gizmo that has a vertical shaft that rotates.  There is a lever hooked to it perpendicular to that shaft - the whole thing looks like a big torque wrench.

 

He's got 14 horses (read 14 hp Kohler engine) to hook to the lever and the lever is 5 ft long.  To turn this lever, make the work and keep constant speed (think 3600 rpms) it takes all 14 horses to pull it.

 

However, at some point, the horses become overwhelmed (read tall patch of grass) with the level of work and James, having done this exercise many times over the years, knows there is a trade off.

 

He makes the lever longer, thus increasing the torque (read torque rise in the engine).  He also removes 2 horses too as the work can be accomplished with fewer horses (read hp) with a longer lever (read more torque), however the rate the work gets done is slower (read 3000 rpms).  None the less, the work gets done.

 

This is exactly how our Kohler cast iron single cylinder engines are designed!

 

So there are 4 elements in an engine that are constantly changing in order to get the job done by design.

 

1.  The engine is running 3600 rpms, no load or light load.  Not necessarily making all the hp the engine could - not required, governor is relaxed somewhat, though the throttle is full open.

 

2.  You hit that tall patch of grass, the governor allows max fuel to the  engine over and above full throttle to try to maintain 3600 rpms.

 

3.  Once the load is larger than the hp AND available torque at that given RPM can handle, the engine slows and the rate of work slows - you no longer have an engine making 14 hp, but...

 

4.  By design, the engine torque rises as the rpms and hp fall.  Still full throttle, governor open full, rate of work slows, but the engine muscles through the tall grass as the torque (read tool for hp to make the work gets longer) rises.

 

At some point the load may become to large to sustain the rpms, regardless of the torque rise and the engine stalls.

 

So IMHO, at the end of the day, torque saved the day.

 

Interesting topic!

 

Thanks,

Bill

[953 nut 51,743]

   Bill, is your last name NYE? That was better than the "Sience Guy" could have said it.  

[Hydro 130]

Bill I think the one issue with your opening post is that your RPM when at 3600 is well above your max torque for the 14 Kohler.  When the 14 fell to 3200 you were still above your max torque so I believe as Terry M says it was your governor that saved the day.

 

If I'm not mistaken the maximum torque generated by our single Kohler engines is somewhere around 2600-2800 rpm depending on the engine and after that the torque curve drops off.  In other words your torque is lower at 3600 than it is at 2800 as an example.

 

I have blown snow now for 2 years now with a 44" 2 stage and an M-16 Kohler.  Last year I started running at 3/4 throttle after reading an article that let me calculate the max torque for my engine.  I found the engine seemed to maintain better and operate more smoothly at 3/4 throttle than it did at full throttle when powering the blower.  With grass however I'm running full throttle because I think the deck cuts better at the higher rpm although the engine is not generating its max torque at that rpm.

 

The 14 I know does not have the torque of the 16 but the principle I believe is the same.   I would suggest the maximum torque will rise to a point as the rpm increases but begins to fall off depending on design well before max rpm is achieved.

[leeave96 487]

Bill I think the one issue with your opening post is that your RPM when at 3600 is well above your max torque for the 14 Kohler. When the 14 fell to 3200 you were still above your max torque so I believe as Terry M says it was your governor that saved the day.

If I'm not mistaken the maximum torque generated by our single Kohler engines is somewhere around 2600-2800 rpm depending on the engine and after that the torque curve drops off. In other words your torque is lower at 3600 than it is at 2800 as an example.

I have blown snow now for 2 years now with a 44" 2 stage and an M-16 Kohler. Last year I started running at 3/4 throttle after reading an article that let me calculate the max torque for my engine. I found the engine seemed to maintain better and operate more smoothly at 3/4 throttle than it did at full throttle when powering the blower. With grass however I'm running full throttle because I think the deck cuts better at the higher rpm although the engine is not generating its max torque at that rpm.

The 14 I know does not have the torque of the 16 but the principle I believe is the same. I would suggest the maximum torque will rise to a point as the rpm increases but begins to fall off depending on design well before max rpm is achieved.

I would agree with this, but suggest that once the RPM's drop below governed speed, the governor has done all it can do - feed the engine the max amount of fuel possible. So next up is the torque rise as the RPM's fall and that additional torque enables the engine to muscle through the tall grass, though at a slower rate of speed.

[Hydro 130]

Yes I agree but if you are operating the engine at its max torque, the torque will not rise above that rpm  it will fall even with higher revs.  The rpm at which the torque is at it's maximum is established by the design of the engine itself based in compression, bore and stroke.   At a given rpm lets say 2800 that's as much torque as there is and torque can only fall whether it be at higher rpm or lower rpm. 

[leeave96 487]

Yes I agree but if you are operating the engine at its max torque, the torque will not rise above that rpm  it will fall even with higher revs.  The rpm at which the torque is at it's maximum is established by the design of the engine itself based in compression, bore and stroke.   At a given rpm lets say 2800 that's as much torque as there is and torque can only fall whether it be at higher rpm or lower rpm.

Yes - I think we are on the same page on this.

Below is a chart showing the HP vs torque vs rpms. It's a little blurry, but is god info.

[pfrederi 17,147]

Horsepower (Clydesdale type)  gets the beer to you, torque gets the top off the bottle so you can drink it!

[roscoemi 245]

Torque is what gets the job done, horsepower dictates at what speed it will get done. The most work and the best mileage from a given motor that is properly tuned is at the torque peak, where it is most efficient.

[RMCIII 838]

Just being me. I like a great discussion that involves math equations. Not to mention physics. Add to that mass, resistance, and well force. So, if the thread is up for it, let's add into this thrust. So how would that factor into the HP/torque question. Does it factor into the equation? Does HP and torque even matter when it comes to thrust? < If it does matter, why? Here is the bonus question... Does anything operate above 100% when it comes to output or performance based on the basic set up of the engine? If it does, or can, how or why does it do so? BTW, I can snuff out, Wikipedia and text book answers.

[oldblue1993 98]

 I will never forget my father deminstrating this with  3/8 wrench and a breaker bar "me the horse and the wrenches torque" basically his meaning was one or both need to increase in order for work to be done, but both need to be increased for efficiency. Nice post I like it when one makes us think.

Edited November 16, 2013 by oldblue1993

[shorts 182]

100% is all you have, their is no more to be had,   100% rated power implies that it is something less than all you have,  A lot of engines are power rated at 100% with a margin  or % of power in reserve, aircraft engines typically have a 5 or 10% safety margin after which exceeding results in a mandatory rebuild/major inspection for reliability and or safety concerns.   any engine can be made to perform at more than 100% rate power with something like the warranty of life being compromised.

[RMCIII 838]

100% is all you have, their is no more to be had,   100% rated power implies that it is something less than all you have,  A lot of engines are power rated at 100% with a margin  or % of power in reserve, aircraft engines typically have a 5 or 10% safety margin after which exceeding results in a mandatory rebuild/major inspection for reliability and or safety concerns.   any engine can be made to perform at more than 100% rate power with something like the warranty of life being compromised.

I'll give you a 2nd chance. Think outside the box. While I completely agree with what you are saying, and you are on the right track, but there are engines that will operate above 100% and are designed to do so.

[shorts 182]

I don't need a second chance,  Knowing that you are Air Force you are referring to roman candles that are just light and run in the solid fuel version, the ones with controls are still not my idea of a normal useable power source but they do have awesome power.

 

Rocket engines.

[RMCIII 838]

SInce you went there, they actually are considered, a source of "additional thrust". Remove an afterburn section and see what your gauges say your thrust reading are. Then, re-attach the AB section, and light the candle. See what your thrust readings are now. It's the only engine desinged to operate above 100%. While gasoline and diesle engines have superchargers, turbo's, nitrous, ect. They are built to ensure the use of the additional component will not cause the engine to "malfunction" at 100%. Jet engines w/AB are designed to withstand tollerences above 100% becasue, at times, they do operate above the 100% margine. I've seen as much as 115% on the gauges used to monitor the engines at "test cell". Quite remarkable.

[shorts 182]

some of the test procedures to determine rated power and life for internal combustion engines involve accelerated power ratings to shorten test times for component wear characteristics, With diesels it is not uncommon to start a green engine, 5 min breakin at no load and then go to rated power (100%) and then add 10% fuel, total of 110% fuel and then run for 1000 hrs. with shutdowns at 250 hr intervals for oil/filter changes and dyno maintainence, test complete at 1000hrs. and engine disassembled for evaluation components. Gas engines typically have a 4 hr breakin and then run at peak hp and peak torque for specific time intervals before end of test power verification and disassembly for inspection.

Edited November 19, 2013 by shorts

[C-101plowerpower 1,605]

hp is how hard you hit the wall, torque is how far you take it with you

 

interesting topic

 

Koen