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HP just isnt the same

D

David G

Well-known Member
I grew up having a utility tractor, JD LA, my dad sold that then, bought a Super A, then sold that later. I bought a JD 18HP lawn tractor, which was way more than either of my dads, have since upgraded it to a 27HP JD lawn tractor which is way more HP than either of my dad's.

Neither of my lawn tractors will pull like the LA or the super A, I might have to get one again.

I have the McCormick 47HP, but it is to heavy to use on the lawn all the time.
 
Kinda like comparing a 400 HP half ton pickup to a 400 HP semi truck, completely different chassis.
 
Engine brake horse power is a bogus "advertisement" scheme. The A has 113 cubic inches and 18 HP on belt, and 16 on thedrawbar. Cubic displacement, torque rise, and hp measured where it is being used, is a major difference. JDs of that era and similar size (JD 40s) were also in that other class of functional power They had the 2 cylinder issues, but worked well on small acres. One sure could see what was happening on an A or SA tractor. The Farmall 100, 130, and 140 fit the same window, and have a bit more power yet. Jim
 
I believe the accurate phrase here is used the the race car industry

Horse power sells parts but torque wins races

Pulling logs with a john deere mc at 17.5 horse power feels different then the 24 horse pwer advertised in the neighbors riding lawn mower.

A few years ago I hauled 2 ton of feed in the back of my 91 and a half dodge cummins pickup for great uncle in his 90s at the time who rode with me. All the way home loaded, every time we came to a hill and went up the hill at the same speed as we were going on the flats, he would look over at me with big eyes and say with a serious face, "this thing has alot of poop!"
 
I've also heard hp is now measured differently. Compare torque numbers. I'm pretty sure that's what's missing
 
Did you ever think about the weight difference, gearing, tire size ect?? I have 27hp exmark lazer zs, and I have a 27 hp ford 1720 tractor, it pulls a 2 bottom plow,you think they lazer z could do that if I could hook the plows to lazer z??? Uhhh, no
 
At first I thought you were talking about Hewlett & Packard.

As I?m sure you know it?s a marketing game. That?s why I choose a Ford 8N over a lawn mower of similar HP. Served me well until I bought a New tractor with live power, hydro, & power steering.
 

This was a frequent hot topic for awhile 10-15 years ago. Some manufacturers got spanked for deceptive advertising. Abig part of it is also RPMs. Big engines will make max HP at 2800, while small ones will turn 7000-8000.
 
What 2 cylinder isues did they have? I had multiple 2 cylinder JDs and never had an issue with them. And I liked the aound of them better than the Farmall we had for 45 years.
 
I agree with Jay. Weight and tire size makes the difference in pulling capability. Take the wheels off from your lawn tractor and set what is left on a cast iron frame with 24 inch tires. Now put a chain driven gear reduction from the current drive axles to the bigger tires and see how it pulls.
 
The Nebraska Tests are still alive and well. The test procedure that was established there is used at many test stations around the world since tractors are generally tested in the country where they are manufactured. The test reports all look the same regardless of the test location and the test methods are identical. On thing that has changed is that they no longer test the smallest tractors - they only do those above a certain power rating, I believe 40 hp.
 
HP ratings on mowers are joke.Does anyone think a Farmall A could be driven by the puny V belt that drives a 20HP mower.Ratings on the new compacts are about as bad, have to be run wide open to come close to the HP ratings.
 
David,
FYI, James Watt invented the term HP to sell his improved steam engine. The definition of HP hasn't changed, 550 ft-lb/s.
However some people measure HP at engine, some at rear wheels, some people exaggerate the HP, some put too big of an engine on a lawn mower.
Some people get confused when it comes to HP and torque.
geo
 
Well my OTR 400 HP Big Cam Cummins was supporting 800 cu. in. and 11 gallons of engine oil, plus a full flow 20 micron and bypass 5 micron filter. It was OTR rated for 80,000# at 4 give or take MPG and could pull it out of a sand pit fully loaded.

Hook that to your 400 hp P/U!
 
Your last sentence is very true, George. Just to pull something requires only sufficient torque at the wheels and enough weight and tire for traction. Given low enough gearing this can be accomplished regardless of engine power and torque. (A winch is a good example - a motor with a couple of horsepower can exert a huge force because it is geared very low and the "traction" is perfect. The old steam engines are also a good example in that they could pull a lot but moved very slowly.) Now to pull a given load at a given speed requires a certain amount of engine power and a gear ratio to allow the engine to run at the proper speed. Engine torque in this case doesn't factor into the equation since maximum wheel torque for a given ground speed is attained when the gearing allows the engine to rev to where it develops maximum power. Engines that develop maximum power at low engine speeds by definition have a lot of torque but it is the power (the combination of torque and engine speed) that is accomplishing the work. Engines like this also tend to have a broad, flat power curve which aids in lugging ability since the power doesn't fall off rapidly as the engine speed drops. Lastly, the engine duty cycle also factors in. High revving engines can make huge power but would not be capable of doing so for hours on end without self-destructing. This is the difference between a 400hp pickup engine and a 400hp semi-truck or tractor engine. Both will make 400hp on a dyno but only the large and low-revving engine can do it on a continuous basis.
 
Having operated both at full load for hours, the pulsing of the Deere just wears me out. Productivity near equal. The 40 RPM range made it much better than a G for instance. Jim
 
The Super A or JD LA had the weight and more reciprocating weight with a heavy flywheel. I think this is also why the latest lawn tractors don't have the pulling power -- they're built lightweight with lightweight flywheels.
 
Well to get down to the nitty gritty it was 855 Cu. in in one of them and one could shoot for one pony power per Cu.in. . and pulling out of a snad pit or old strip mine with 80000 Net would not even get you into the bell ringers class as you were 15 to 20000 light in the wagon . I do so love guys with there hopped up pick ups bragging about HORSE POWER . When talking about HORSE POWER let me know when ya can drag 2000000lbs up little humps like Fancy gap , Bald Eagle and some of the other little humps at 75 MPH . When ya start having pistons swapping holes or ya lift the head or even throw the crankshaft on the ground then ya know you went to far . Best performing pick up i ever had was NOT a diesel it was a Ford with a 460 gas . The ADVERTISED Hp. is a mind game selling point . And likes said Torque is what gets the job done and working the engine in it's peak torque range NOT it's peak Horse power . Not long ago small engine Mfg. were sued on there ADVERTISED Hp. Now you see only Cu. IN or CU. CC. and it i guess up to to call it what ever hp. Bore size and Stroke . Large bore long stroke gets the job done and will last longer .
 
I agree. For some reason, I fail to see how it can be an accurate comparison when one engine is rated with a 50:1 gear reduction and another is 1:1.
 
Never a problem like that in all we had. AC dealer claimed that was what broke the AC60 combine but he shut up about it when was told the combine had tha AC combine engine mounted on the toung and the other one was not breaking things pulled behind the JD on PTO.
 
A 70 hp tractor 54 years ago ain?t the same as the 70 hp kubota lawn mowers they make today either
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All three.

I just never seem to have the right size tractor, have the JD X590, McCormick C47, and Ford 6610. I could use something with the weight and traction of super A, but would only use it a couple times a year.
 
Yepper cubes matter and dragsters will tell you/show you that. On the tugging of the 400, seems you had more of a workout than I had. I retired from industry and loved to play in the sand with my toy trucks when a kid. Decided to buy a rock bucket and haul for fun and the completion of a life long childhood ambition. Was fun being out at the pit on a cool winters morning, ponds everywhere so puddle ducks (Mallards, Pintails, Redheads) made for some beautiful viewing at first light.

I had a '91 Ford 460, 4 OD on the floor, gasser, dually, farm truck. Loved it...other than filling the tanks.....a PIA. Only stick shift vehicle I ever had that I could dump the clutch at idle and the engine would take it.
 
Neighbors have the big stuff, can get them anytime.

I would like one adjustable size tractor.
 
(quoted from post at 22:23:29 04/27/20) Neighbors have the big stuff, can get them anytime.

I would like one adjustable size tractor.
Click to expand...

I hear that was attempted with the ETD but it never really took off.

Carl
 
(quoted from post at 22:37:06 04/25/20) I grew up having a utility tractor, JD LA, my dad sold that then, bought a Super A, then sold that later. I bought a JD 18HP lawn tractor, which was way more than either of my dads, have since upgraded it to a 27HP JD lawn tractor which is way more HP than either of my dad's.

Neither of my lawn tractors will pull like the LA or the super A, I might have to get one again.

I have the McCormick 47HP, but it is to heavy to use on the lawn all the time.
Click to expand...

It is quite concerning to see so many people with such limited knowledge of basic physics. Plus having this perverse tendency to compare apples and oranges.

looking at the 27HP X720 2WD, ,X724 2WD AWS, X728 4WD & X729 4WD AWS. At 844lbs, 915lbs, 925lbs and 1134lbs. With 26X12-12 turf tires.
Vs
The L with 10HP and 1515lbs and 6.00-22 Chevron tires .
LA with 13HP and 2200lbs with 8.00-24 Chevron tires.

Well duh,,,,,,,,,,,,,,,,,,,,,,,which is going to output the other ???

Belt the L or LA to a 15Kw alternator and connect the X724 to a 15Kw pto generator .
Even the LA won't carry a 9.0Kw electrical without bogging rpms, loosing frequency and dropping voltage .
The X724 will be purring along at 9.0Kw at only 58% of capacity. With reserve for more load or starting electric motors.

I do hope that nobody needs to have it explained to them which tractor will output the other .
 
Horsepower is just a calculated number based on torque and RPM. Early D8's had less than 200hp, but only revved around 900 RPM, so the HP number was small, but TQ was high. When all the tiers and HP levels for your company and all that crap came out, it became very popular to de-rate engines, I'm sure others do to, but JD had a handy chart on their website to tell you where to set the governor to hit "49HP". At the time we had a Kenworth ten wheeler that was a portable concrete batch plant that we used for concrete backfill around pipes. It had a "315" Cummins- which I had never heard of, but it only revved to 1800 RPM. Turns out it was basically a 350 with the governor turned down
 
Torque Snorque . So many people can only think of torque, torque and torque .
Horsepower is a measure of how much work can be done per hour.
Take your "High Torque" engine with 300lb ft and 1200rpm. It can only accomplish 90% of the work that a "low torque engine with 200lb ft and 2000rpm can.
 
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