oliver28472
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My Buck has the K3B. I think it is about 18 at the flywheel.
Beaver 370d clutch problem
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Ilikeurtractor
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K3B engine is rated at 15.5 PS at the flywheel according to the performance curves I have. Bolens hyped it up to 17 hp. I think they arrive at 17 since it probably takes around 2 PS to turn the engine over. Just a way to play with the numbers.
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Ilikeurtractor
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Evidently there are different flavors of the same displacement engine out there.
Attached are examples of hp claims for the K series engines. In the Bolens manuals, they publish the power ratings as 14 and 15.5 PS for the K3A and K3B engines respectively in the G15x/G17x tractors.
The KE70 and 75 are rated at 13 and 14.8 PS which were also in the G15x/G17x tractors (early years).
The sticker on my Satoh claims 16.5 hp for a K3A-11BE and that matches up with the specs in the Mitsubishi manual. The term "bare hp" needs definition for me. This also shows the K3B engine with 18.5 hp.
So, in the end I'm not sure what to believe. I lean towards the curves as they appear a little more scientific than just claims on a sticker or manual. A little more information on the engine versions, which I'm assuming has to do with the suffixes would be helpful. I just checked my G174 (Iseki TX2160) and it has a "K3B-11GT" sticker on the valve cover. Hard telling what the differences are with that and the "11BE" version.
Note also that 1 PS = 735 watts. 1 hp = 746 watts. So a PS is slightly less than a hp.
Attached are examples of hp claims for the K series engines. In the Bolens manuals, they publish the power ratings as 14 and 15.5 PS for the K3A and K3B engines respectively in the G15x/G17x tractors.
The KE70 and 75 are rated at 13 and 14.8 PS which were also in the G15x/G17x tractors (early years).
The sticker on my Satoh claims 16.5 hp for a K3A-11BE and that matches up with the specs in the Mitsubishi manual. The term "bare hp" needs definition for me. This also shows the K3B engine with 18.5 hp.
So, in the end I'm not sure what to believe. I lean towards the curves as they appear a little more scientific than just claims on a sticker or manual. A little more information on the engine versions, which I'm assuming has to do with the suffixes would be helpful. I just checked my G174 (Iseki TX2160) and it has a "K3B-11GT" sticker on the valve cover. Hard telling what the differences are with that and the "11BE" version.
Note also that 1 PS = 735 watts. 1 hp = 746 watts. So a PS is slightly less than a hp.
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284 International
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My understanding is that the agricultural industry are sticklers for accurate horsepower ratings. A survey of tests of similar type and vintage tractors indicates the manufacturers knew what they were saying when independent testers inspected their products. A few examples: Sato S650 claimed PTO horsepower is 22, tested PTO horsepower is 22.03. Engine hp is 25. Yanmar YM240: claimed PTO hp is 19.756, tested horsepower is 19.76. Engine hp is 24. Kubota L245 claimed PTO hp is 22, tested is 22.35. Engine hp is 25.
The Japanese market rates their tractors in terms of PTO horsepower, so corresponding products between markets are rated rather differently. For instance, the engine in my Japanese market YM2000 is identical to my US-market YM240. Apart from insignificant differences in throttle linkages and PTO gears, they are absolutely identical. But the YM2000 engine plate rates things at 20 hp, and the YM240 plate says 24 hp. The tractor model numbers correspond to their respective ratings, even though they are mechanically identical.
Similarly, Kubota's L245 was originally the L2201. 22 PTO horsepower in Japan, but 25 horsepower in the states. Smaller tractors carry the tradition through. An 18 horsepower YM186 is identical to a 15 hp YM1510. I think the Beavers are around 14 PTO horsepower in Japan, and 17 or so engine horsepower in the US. The fraction of PTO to engine horsepower is pretty close across the board with this size tractor, too, with models that have been independently tested. There is about 15% less PTO horsepower than engine horsepower. The "bare" horsepower rating then should be the engine horsepower, while the power curve numbers or Japanese market specs are actual output at the PTO.
The Japanese market rates their tractors in terms of PTO horsepower, so corresponding products between markets are rated rather differently. For instance, the engine in my Japanese market YM2000 is identical to my US-market YM240. Apart from insignificant differences in throttle linkages and PTO gears, they are absolutely identical. But the YM2000 engine plate rates things at 20 hp, and the YM240 plate says 24 hp. The tractor model numbers correspond to their respective ratings, even though they are mechanically identical.
Similarly, Kubota's L245 was originally the L2201. 22 PTO horsepower in Japan, but 25 horsepower in the states. Smaller tractors carry the tradition through. An 18 horsepower YM186 is identical to a 15 hp YM1510. I think the Beavers are around 14 PTO horsepower in Japan, and 17 or so engine horsepower in the US. The fraction of PTO to engine horsepower is pretty close across the board with this size tractor, too, with models that have been independently tested. There is about 15% less PTO horsepower than engine horsepower. The "bare" horsepower rating then should be the engine horsepower, while the power curve numbers or Japanese market specs are actual output at the PTO.
Ilikeurtractor
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I agree with everything you said and there is a lot of evidence out there to support it. The only problem I have with the curves I posted is that they state "K3A" and "K3B" Engine performance curves. If the curves represented PTO horsepower, I would think they would label them as the respective tractor designations such as TX2160 or TX2140 PTO output, but understand if that's the convention over there then everybody "knows" they mean PTO output.
One other thing that makes me question if it's PTO output is on my KE70 engine, it has "13 PS" cast right into the engine block. If that engine was used in other equipment, say a generator or forklift or whatever, then that would seem odd they would cast a PTO power rating for a tractor into it. Then again, maybe Mitsubishi only sold the KE70s for tractors, but it just seems odd to me they would limit their market in case another manufacturer came along and wanted to use it for something else.
I would also suspect that with the multitude of PTO speeds the Japenese tractors came with that the efficiencies across the speeds are different, resulting in slightly different PTO outputs. That would seem to complicate the ratings even more.
Great discussion. Can we have a Mitsubishi tractor designer jump in and solidify some of this information?
One other thing that makes me question if it's PTO output is on my KE70 engine, it has "13 PS" cast right into the engine block. If that engine was used in other equipment, say a generator or forklift or whatever, then that would seem odd they would cast a PTO power rating for a tractor into it. Then again, maybe Mitsubishi only sold the KE70s for tractors, but it just seems odd to me they would limit their market in case another manufacturer came along and wanted to use it for something else.
I would also suspect that with the multitude of PTO speeds the Japenese tractors came with that the efficiencies across the speeds are different, resulting in slightly different PTO outputs. That would seem to complicate the ratings even more.
Great discussion. Can we have a Mitsubishi tractor designer jump in and solidify some of this information?
284 International
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Where did you find the dyno sheet? I have that one, too, but don't remember where I found it.
I know more about the Yanmar products. Many of their tractor engines are also used in marine applications, generators, and refrigeration units, as well as industrial applications. While many/most parts interchange, the engine model numbers and their power ratings do vary markedly. For instance, the version in my Yanmar tractor of a small 3 cylinder diesel is 18 engine, 15 PTO hp at 2600 RPM in the tractor, but nearly 24 horsepower in industrial applications, at 3600 RPM. In marine applications output varies according to the rated RPM but is generally higher, presumably because of the unlimited cooling capacity. Different casting numbers exist for all these applications even though parts are interchangeable.
It seems like the power curve listed is from a tractor manual, and thus is "as-installed." I would predict Mitsubishi would be similar to Yanmar and have different numbers and outputs if engines in the same family, depending on application.
I'm not sure about the different PTO speeds vs efficiency. I don't think there would be meaningful differences, but I don't have any evidence for that. Gear efficiencies shouldn't change unless there are additional gears within the drive train in different speeds. Otherwise, the power should be the same.
I know more about the Yanmar products. Many of their tractor engines are also used in marine applications, generators, and refrigeration units, as well as industrial applications. While many/most parts interchange, the engine model numbers and their power ratings do vary markedly. For instance, the version in my Yanmar tractor of a small 3 cylinder diesel is 18 engine, 15 PTO hp at 2600 RPM in the tractor, but nearly 24 horsepower in industrial applications, at 3600 RPM. In marine applications output varies according to the rated RPM but is generally higher, presumably because of the unlimited cooling capacity. Different casting numbers exist for all these applications even though parts are interchangeable.
It seems like the power curve listed is from a tractor manual, and thus is "as-installed." I would predict Mitsubishi would be similar to Yanmar and have different numbers and outputs if engines in the same family, depending on application.
I'm not sure about the different PTO speeds vs efficiency. I don't think there would be meaningful differences, but I don't have any evidence for that. Gear efficiencies shouldn't change unless there are additional gears within the drive train in different speeds. Otherwise, the power should be the same.
Ilikeurtractor
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The curves were in one of the manuals I've acquired over the years (specifically for the TX2140/TX2160 Iseki/Bolens G15x/17x tractors). I've only have one manual that had curves and it was only for those engines. I wish more were available.
I ran some efficiency numbers from the graphs, and if you use the lowest specificy fuel number (210 g/PS/hr) the efficiency is around 27% (using the BTU content of one gallon of diesel @ 139,500 BTU). If you factor in an 85% gearbox/PTO efficiency, then the numbers go to around 32% for the engine. According to some sources on the net, "average" diesels should be between 31 and 44% efficient at their peak efficiency. So that would tend to support the graphs being PTO power outputs.
I ran some efficiency numbers from the graphs, and if you use the lowest specificy fuel number (210 g/PS/hr) the efficiency is around 27% (using the BTU content of one gallon of diesel @ 139,500 BTU). If you factor in an 85% gearbox/PTO efficiency, then the numbers go to around 32% for the engine. According to some sources on the net, "average" diesels should be between 31 and 44% efficient at their peak efficiency. So that would tend to support the graphs being PTO power outputs.