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

[GeneV]

So if I understand correctly, hp is primarily linked to top speed, but not necessarily torque?

 

[MossRoad]

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"

 

[tjkubota93]

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.

 

[GeneV]

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.

 

[cdaigle430]

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

 

[Frogmore]

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.


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.


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.

 

[WranglerX]

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

 

[MossRoad]

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.

 

[RalphVa]

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

 

[GeneV]

I've had a few zoom zoom mazdas, even got one now.