Buying Advice need advice for new kubota

   / need advice for new kubota #11  
I would sit down and try and make a wishful thinking list of the things I might want to do or do now that could be much easier with a front loader, a pto, and a 3pt hitch. It sounds like you've started but it's not as easy as you think. Do you have a garden or is it one of those things you would like to have? If so a tiller could be a nice future option or something you may want to rent.

Do you landscape your yard? A front loader makes a very easy way to move bags of mulch, stone, and bark to where you need it. Plus they are real nice for moving rocks. The front loader is one of the few options that really should be purchased when you buy the tractor.

If you're thinking of moving up from a lawn mower into a small tractor then it's worth figuring out the less obvious things it can do. That way you can make a much better choice. Most of the attachments can be bought afterwards but a LOT of people here have bought a tractor only to sell it to upgrade a few years later because they just didn't realize how much easier they can make life.

I wouldn't be worried about going from 25hp gas to 18hp diesel as the torque is more important than HP. Torque is a measurement of real force while HP is a calculated number (basically how much work can be done in a measured amount of time). For example if you try to remove a screw with a screw driver as you try to twist it you are applying force (torque), if the screw doesn't turn then you have made 0 hp. If it spins very fast then you've made lots of HP.

Torque in a small gas engine starts low raises up as RPM increases, peaks around 2400 rpm, and then drops off. What that means is a 25hp engine needs to be running at peak RPM (usually 3600) to make 25hp. When the gas engine starts to bog down, say to 2400 rpm where it reaches it's peak torque the HP will drop, it could be as low as 15hp to 20hp but with the torque increase the engine still has plenty of power. But if the gas engine drops further the HP drops like a stone because the torque drops off quickly.

A diesel engine makes a lot of torque. It starts off at low RPMs and goes up to the point at where the gas engine hits it's peak torque, 2400ish, then it drops off very fast. So diesel engines don't rev up as high as gas engines, the very low torque at higher more than offsets the higher HP. So diesel engines usually run at a point just a little higher than where the torque starts to drop off so as they start to load they hit full torque.

Now what this means is if a gas engine is running at full RPM then you're not using it's full torque and are not using the full potential of the engine. If you load it down enough to hit it's full torque then it's now equal to a smaller diesel engine. If you load it down even further the torque drops off so quickly the smaller diesel engine now outperforms it.
 
   / need advice for new kubota #12  
How is 20HP not equal to 20HP?


How much more torque will a 20HP diesel engine produce over a 20HP gas engine?

ps:
Please keep in mind the OP is considering a BX-series tractor. This is a clue. ;)


Wrooster

Ah, I don't think I ever said 20 hp is not the same as 20 hp, now did I? I said a 20hp diesel engine (which probably produces 30 ft/lbs torque) is not the same as a 20 hp gas engine (that may only produce 19 ft/lbs torque).

I do like crazyyal's post on the subject and realize you responded before he posted it, but it speaks to my point.

Since both 20hp motors were hypothetical, lets look at a more real world example.

2012 Jetta TDI - 140hp - 236 ft/lb torque.
2012 Jetta gas - 170hp - 177 ft/lb torque.

I've driven both. The TDI will sink you well back into the seat off the line, it's a lot of fun to drive. When you're passing a semi on the hwy, hp is a little more important, but out in the field, it's all torque.
 
   / need advice for new kubota #13  
How is 20HP not equal to 20HP?


How much more torque will a 20HP diesel engine produce over a 20HP gas engine?

ps:
Please keep in mind the OP is considering a BX-series tractor. This is a clue. ;)


Wrooster

Good point, we are talking about BX's, so the numbers are small.

In my experience, readings, and recent trends of rating gasoline engines by displacement and torque instead of horsepower, makes me believe they have been fibbing to us about the true output of their engine. I do not believe the same is true of diesels.

Most 20 hp diesel engines turn 3200 rpm, which will result in a torque of 32.8 ft-lb. Most 20 hp gasoline engines turn 3600 rpm, which will result in a torque of 29.2 ft-lb. So, there is a torque difference, albiet small. Plus, I think the 20 hp output of the diesel engine is closer 20 hp than the 20 hp output of the gasoline engine (fibbing again). Since 20 hp = 20 hp, the only difference in torque would be if there was a change in operating rpm.

Philip
 
   / need advice for new kubota #14  
Good point, we are talking about BX's, so the numbers are small. Most 20 hp diesel engines turn 3200 rpm, which will result in a torque of 32.8 ft-lb. Most 20 hp gasoline engines turn 3600 rpm, which will result in a torque of 29.2 ft-lb. So, there is a torque difference, albiet small.
Thank you. :drink:

The difference in torque is roughly 10%, at best.

Plus, I think the 20 hp output of the diesel engine is closer 20 hp than the 20 hp output of the gasoline engine (fibbing again).
I forget which outdoor power equipment manufacturer recently got slapped for "overzealous" advertisement of HP numbers. It's sort of like the "5.5 Peak HP" Shop-Vac that I have... :laughing:

Since 20 hp = 20 hp, the only difference in torque would be if there was a change in operating rpm.Philip
Thank you. :drink:

The difference in HP is 0%.

Wrooster
 
   / need advice for new kubota #16  
I own three acres and bought a BX about 5 years ago. There has been no looking back. Its mows so much better and safer as I have some hills. I'm not sure how much snow you get, but you might get by with an end loader and a rear blade for snow removal. Snow blowers are expensive, and you can do a lot of other stuff with an end loader. I didn't originally get an end loader when I bought mine, but added it a few months later. Half the hours on my machine are using the end loader.
 
   / need advice for new kubota #17  
2012 Jetta TDI - 140hp - 236 ft/lb torque.
2012 Jetta gas - 170hp - 177 ft/lb torque.

I've driven both. The TDI will sink you well back into the seat off the line, it's a lot of fun to drive. When you're passing a semi on the hwy, hp is a little more important, but out in the field, it's all torque.

Be careful comparing Turbo-aftercooled engines with naturally aspirated engines. In diesels, you always need a larger displacement NA engine to make the same hp as a gasoline NA engine. The torque people talk about from diesel engines comes from the turbo, which most of these small engines do not have. Turbo-diesel aftercooled engines make high boost at low rpm leaning on the wastegate to make lots of low end torque and a really nice flat torque curve. My NA diesel tractor (and most other here without turbo) does not benefit from this. NA diesel engines just do not have that mystical torque rise as TA diesel engines. Philip.
 
   / need advice for new kubota #18  
Huh?


Wrooster

OK, seeing what I wrote again, technically you're right, but I did say A 20 hp diesel ... which infers the word engine at the end of the sentence, a word I though I added, but obviously did not.

Be careful comparing Turbo-aftercooled engines with naturally aspirated engines. In diesels, you always need a larger displacement NA engine to make the same hp as a gasoline NA engine. The torque people talk about from diesel engines comes from the turbo, which most of these small engines do not have. Turbo-diesel aftercooled engines make high boost at low rpm leaning on the wastegate to make lots of low end torque and a really nice flat torque curve. My NA diesel tractor (and most other here without turbo) does not benefit from this. NA diesel engines just do not have that mystical torque rise as TA diesel engines. Philip.

issh, tough crowd. I'll start with cars. I though I'd stick to a single engine manufacturer to be fair, but maybe you'll like this comparison better.

2012 Subaru WRX (with high-pressure turbocharger and high-capacity intercooler) 265 hp - 244 lb-ft torque.

2012 Jetta TDI (2.0 TDI, in-line 4-cylinder, turbocharged direct injection, common rail ) 140 hp - 236 lb-ft torque.

OK, let's move back to tractors. According to Kioti, my tractor (CK30 HST) has 30 engine hp and 9.6 kgf-m. Now what the hel l is 9.6 kgf-m? I didn't know either, but if the online conversion tool is correct, it is equal to 69.44 lbf-ft. So my 30 hp diesel produces approx 70 lb-ft torque, you just don't get that torque to hp ratio in a gas engine and is why I say A 20 hp diesel engine is not the same as A 20 hp gas engine.

Sources:

KIOTI - run ahead of the pack!

Features & Specs < 2012 Jetta | VW Models | Volkswagen Canada < Models < Volkswagen Canada

Specifications - 2012 WRX & WRX STI - Subaru Canada
 
   / need advice for new kubota #19  
Lets try to compare apples to apples. Both Kubota engines. Both naturally aspirated. Both nearly same displacement.

Kubota WG972-G-E3 gasoline engine. 962cc. 32.5 peak hp @ 3600 rpm. 55 peak ft-lb @ 2300 rpm.

Kubota D1005-E3B diesel engine. 1001cc. 24.8 peak hp @ 3600 rpm. 41 peak ft-lb @ 2400 rpm.

Fact, same displacement, gasoline makes more torque and horsepower. Peaks are about same rpm.

You have to add a turbo to make a diesel a torque monster.

Philip/
 
   / need advice for new kubota #20  
I'll stir the pot a bit more here! Most diesels are liquid cooled and can develop torque that an air cooled engine can't!
 

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