My garden tractor is 26hp, my scut tlb is 22.5, how come?

   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #1  

GeneV

Elite Member
Joined
Aug 19, 2019
Messages
3,202
Location
Lake County, IL
Tractor
Bradley 48" stander MF GC1710
I'm sure this has been answered before, but just gimme the quick&dirty. Why scuts are powered less than some garden tractors?
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #2  
Torquey diesel with a legit horsepower spec, versus an overly optimisitic rating of a gasser?

Do you have the torque numbers on each?

At what RPM is the HP rated? It’s easier to achieve higher HP numbers on engines set up for higher RPM, but they’re going to lack grunt.
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #3  
That’s just life. There is no reason!
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come?
  • Thread Starter
#4  
Torquey diesel with a legit horsepower spec, versus an overly optimisitic rating of a gasser?

Do you have the torque numbers on each?

At what RPM is the HP rated? It’s easier to achieve higher HP numbers on engines set up for higher RPM, but they’re going to lack grunt.

Naw, I don't have all those specs. But I'm just saying, my gt is fairly capable. Before my gc1710, that's what I was using. I have a snow/dozer blade for it, I would plow with it and level off rooted dirt (I had pigs). And obviously mow with it, actually that's what I still mow with. It muscles through all the slopes and ruts I have here, mostly. It did all that ok enough on its own with 2wd and locking differential. In 4wd, it would be a little beast.
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come?
  • Thread Starter
#5  
That’s just life. There is no reason!
There is tho! Just gotta find it, I heard about dmt on joe rogan's podcast. :D
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #6  
Naw, I don't have all those specs. But I'm just saying, my gt is fairly capable. Before my gc1710, that's what I was using. I have a snow/dozer blade for it, I would plow with it and level off rooted dirt (I had pigs). And obviously mow with it, actually that's what I still mow with. It muscles through all the slopes and ruts I have here, mostly. It did all that ok enough on its own with 2wd and locking differential. In 4wd, it would be a little beast.

My 1963 Cub Cadet 123 was the same, and likely moved more dirt in its life than 95% of compact utility tractors sold today, it just did it much more slowly.
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #7  
Part of your answer probably is in the torque difference. A diesel generally has a lot of torque but is relatively low in horsepower. You'll also see differences in the gearing. The wheel size may be a factor as well, I'm no sure on that one.
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #8  
I've got the charts for my Sears get and my Bolens/Iseki. The Sears is rated at 3600 rpm for 20 hp and 33.3 ft. lb of torque at 2400 rpm. It displaces 624 cc.
The Bolens is rated at 2600 rpm for 14.5 hp and 30 ft. lb of torque at 1800 rpm. It displaces 776 cc.
That said, the Bolens weighs about 600 lb more. That and the gearing is where you feel the difference. I've pushed snow and plowed the garden with both. The Bolens seems to do those tasks more easily, I believe weight is the difference. Mowing is pretty much the same, but my grass doesn't get real long between cuttings.
The Bolens also uses less fuel, even though it has a higher displacement.
I think HP sells mowers. Weight and torque make a tractor.
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #9  
Your MF has a 68 cubic inch engine.
Your Craftsman has a 45 cubic inch engine.

Horsepower is horsepower no matter what produces it. Your bigger engine has 50% more displacement and probably much longer connecting rods. Longer connecting rods means longer levers. Longer levers mean more torque.

While both engines will make similar horsepower, the bigger displacement one with longer levers will be able to produce more torque and keep it in that torque range longer than the smaller displacement engine.
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come?
  • Thread Starter
#11  
So if I understand correctly, hp is primarily linked to top speed, but not necessarily torque?
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #12  
So if I understand correctly, hp is primarily linked to top speed, but not necessarily torque?

Not top speed, but how quickly an engine can do a certain amount of work.

"Torque is simply a force acting on something from a distance (i.e. a piston pushing down on a crankshaft, using that leverage to rotate it), while horsepower is torque multiplied by RPM, or a measurement of how quickly an engine can accomplish a certain amount of work"
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #13  
I think those over the road diesels have 300 or 400 hp and massive amounts of torque. Diesels are low rpm.

It's kinda like comparing a chainsaw to a lawnmower. The chainsaw has 5hp, but it's at 13,000 rpm. The mower is at 3600 rpm.
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come?
  • Thread Starter
#14  
I think I'm getting this, thanks guys.

Anyways, this thread was kinda linked in thought to another thread I posted yesterday about Case 600 series tractor/loaders. Actually, I think they were like 18 hp gassers. They were the size of a garden tractor, but were little beasts. Just no 4wd.
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #15  
I have the MF GC2410 and a Husqvarna 2448. There is a big difference especially the MF being liquid cooled and the Husqvarna air cooled. As stated earlier its all about the torque...I like this question :)
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #16  
Here is the performance curve from a Kawasaki FD711D (a high-end water cooled 2 cylinder gasoline engine. This engine is probably rated at 25 or 26 HP. While it can support that (@3600 RPM) it can't do it continously.
FD711D.PNG

Here is the performance curve from a Kubota D1105 (a water cooled diesel engine used in some small tractors). Notice how much less the torque drops at higher RPM, but the more important line is the NET CONT one. This one shows that it can output over 14HP @2000 RPM (or almost 22 @3000) all day long. The gas engine shows 10HP @2000 and just over 14@3000. So, the diesel when it is just above idle can ouput as much power as the gas one at almost full throttle.
sae-j1349-d1105[1].jpg

Gearing can make up the difference in the top RPM difference between gas and diesel. But, diesels are known for being able to make significant power at lower RPM. Torque * RPM = Horsepower. So, it really is all about making more horsepower at lower RPM for longer periods of time. Depending on the job, you might or might not need all that power (torque). For a lawnmower, most of the time it is mowing average grass and does not need that much power to do it. But, if you let the grass get really long and are mulching, the horsepower requirement will increase dramatically. A diesel is likely to handle that much better than a gas engine.
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #17  
I'm sure this has been answered before, but just gimme the quick&dirty. Why scuts are powered less than some garden tractors?

BUT, BUT, BUT you have high speed (rabbit) and low speed (turtle) and 2 wheel drive or 4 wheel drive and torque and PTO.... Hp is not everything without torque...

Dale
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #18  
Here is the performance curve from a Kawasaki FD711D (a high-end water cooled 2 cylinder gasoline engine. This engine is probably rated at 25 or 26 HP. While it can support that (@3600 RPM) it can't do it continously.
View attachment 639053

Here is the performance curve from a Kubota D1105 (a water cooled diesel engine used in some small tractors). Notice how much less the torque drops at higher RPM, but the more important line is the NET CONT one. This one shows that it can output over 14HP @2000 RPM (or almost 22 @3000) all day long. The gas engine shows 10HP @2000 and just over 14@3000. So, the diesel when it is just above idle can ouput as much power as the gas one at almost full throttle.
View attachment 639054

Gearing can make up the difference in the top RPM difference between gas and diesel. But, diesels are known for being able to make significant power at lower RPM. Torque * RPM = Horsepower. So, it really is all about making more horsepower at lower RPM for longer periods of time. Depending on the job, you might or might not need all that power (torque). For a lawnmower, most of the time it is mowing average grass and does not need that much power to do it. But, if you let the grass get really long and are mulching, the horsepower requirement will increase dramatically. A diesel is likely to handle that much better than a gas engine.

Kawasaki FD711D is 745cc 2 cylinder engine
Kubota D1105 is 1123cc 3 cylinder engine

The diesel needed 1 more cylinder and 150% displacement to achieve that.... just sayin. ;)
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come? #19  
Diesels produce A LOT more torque. Gasoline engines with turbos can match it, but not plain carbed or injected engined ones. Our 1983 240D Benz would have been great if it had as much as 100 hp, and the turbo ones with 120 were great. Would be a match of our Mz3 gas (non turbo) with 186 hp. The VW TDI with turbo diesel 150 hp drove like it had a small V8 as long as you stayed within the turbo's flat torque/hp curve. We had very definite shift points of 15, 25, 35, 45 and 55 mph on it. These same points have worked on all previous makes until we got the Zoom Zoom Mazdas.

Ralph
 
   / My garden tractor is 26hp, my scut tlb is 22.5, how come?
  • Thread Starter
#20  
I've had a few zoom zoom mazdas, even got one now.
 

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