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Discussion Starter · #1 ·
I was debating for a long time whether it's worth it making this post but here we are prompted by latest TTWT video.

A beautiful custom setup with this mower and with laser box blade those 2 are something special.
However it was mentioned that tractor seemed happier PTO rpm wise when at slightly lower engine rpm. I very rarely use full rpm on my tractor and any other diesel equipment. There are several reasons why.
Firstly diesel engine usually provides maximum torque and power at much lower rpms when compared to gasoline engine. This is the same for engine in our 4052R which I will get back to later.
Passive regen is one hell of a mystery on these machines but from what I read it happens when engine is working in its optimal power window. From what I observer over hundreds hours of field work is that passive regen usually happens around 2100-2200 engine rpm when using taxing implement. Think mowers, baler, ground engaging stuff. When using higher rpms sooth build up was higher when compared to using lower rpms than 2100.
Lastly every time I we were given guidelines by our dealer on how to operate any implement we were always told to keep engine rpms in moderation. From my experience there is really no need for pushing 540. I have not noticed any difference while mowing, tilling, baling, wood chipping,... We even have some implements that suggest running specifically at 450 PTO rpm, not higher, that translates roughly to 2100-2200 engine rpm range.

When our tractor was at dyno what I really wanted to see was the torque and power curve. Here is the partially translated version with some personal information removed but should be sufficient to further my case.
Rectangle Slope Plot Font Parallel


4052R stock engine is represented by dashed line. As can be (not so clearly) seen maximum power is available at roughly 2100 engine rpm.

I am using this post mainly as callout to @Tractor Tim . Would it possible to show these power curves from your dyno measurements? Comparison of both stock and turbo 1R engines might have drastically changed them as well. (Using this method as I hope it will work unlike YT comments and might be beneficial for others.)
I would also like to see dyno power and torque curves of other models and engines if you guys have them available and anything else that might be added to this topic.

By no means I am saying that these engine can not run at full rpm. I am simply suggesting there is basically no good reason to do so.
 

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Wouldn't the typical 1-series engine results be different since Tim installed a custom turbo on that engine?
 

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I'll bite....I never go full retard/throttle.......it just don't compute with me.

2700 is enough.........ymmv
 

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Mowers are designed for 540rpm input, they may work ok at a lower rpm but won't have the same blade tip speed. If you are using a tractor at the upper hp range of an implement you won't notice using lower rpm as much as a tractor with the min hp.

I remember reading years ago that you want a torque rise when a tractor runs out of power and the rpms drop. You want a higher torque at a lower rpm than you are running so when it bogs down you actually get more power. If not you would have to start downshifting like an 18 wheeler going up a hill, if you're tilling you want to keep your speed up to get through soft ground not slow down.
 

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We had a 240D Benz for 25 years. Believe you me that it needed max rpm many times, especially in 1st and 2nd gears. Otherwise, with 65 hp, you don't move very fast. My wife could actually outrun most vehicles across town in it. It would make it fine going up Afton Mtn west of us on I-64 if you could maintain speed above about 65 mph. Drop below that, and you're down to 3rd gear and cannot shift to 4th because the maximum is 55 mph. The engine needed maximum hp to get over the mountain at speed.

However, the tractors are different. I needed max rpm on the 18.5 hp JD 4010 a lot of the time, but do not need the huge amount of hp in either the 1025R, 2025R or the B2601. Usually run those at 450 rpm PTO speed on both brush hog and wood chipper. These work fine at these lower rpms.
 

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Discussion Starter · #8 ·
Mowers are designed for 540rpm input, they may work ok at a lower rpm but won't have the same blade tip speed. If you are using a tractor at the upper hp range of an implement you won't notice using lower rpm as much as a tractor with the min hp.

I remember reading years ago that you want a torque rise when a tractor runs out of power and the rpms drop. You want a higher torque at a lower rpm than you are running so when it bogs down you actually get more power. If not you would have to start downshifting like an 18 wheeler going up a hill, if you're tilling you want to keep your speed up to get through soft ground not slow down.
I definitely did not notice any difference in cut either with flail mower or disc mower. In heavy or normal grass. We have brush hog but currently its out of commission. But I definitely ran it at 450rpm and there was not anything to complain about with final cut. (There was later but because blade was as sharp as a ball.) For me it feels like tip speed is only important when lawn quality cutting is required so just finish mowers.
Our gas Z545R I run at wide open quite often but linear power increase typical for gas engines is really noticeable on that one.
 

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Discussion Starter · #9 ·
We had a 240D Benz for 25 years. Believe you me that it needed max rpm many times, especially in 1st and 2nd gears. Otherwise, with 65 hp, you don't move very fast. My wife could actually outrun most vehicles across town in it. It would make it fine going up Afton Mtn west of us on I-64 if you could maintain speed above about 65 mph. Drop below that, and you're down to 3rd gear and cannot shift to 4th because the maximum is 55 mph. The engine needed maximum hp to get over the mountain at speed.

However, the tractors are different. I needed max rpm on the 18.5 hp JD 4010 a lot of the time, but do not need the huge amount of hp in either the 1025R, 2025R or the B2601. Usually run those at 450 rpm PTO speed on both brush hog and wood chipper. These work fine at these lower rpms.
That to me sounds more like engine being not adequate for vehicle weight. That is a problem with almost every single car being sold in Europe now. With measly 1.0 or 1.2l engines to pull 2tons of weight. Ridiculous. I assume that benz engine had turbo if not that was the problem.
 

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Discussion Starter · #10 ·
So 53.6 HP or 54.4 PS. Pretty good I'd say.

The attached came from a Ecotune video so take it for what is wortha. Also attached is a Yanmar chart for a 4TNV86-CT. Not sure if that one helps.
As I said dashed line is the stock engine so ~36hp on the pto. Other stats are for slightly different measurement. Thats for something else not yet ready to post.
 

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That to me sounds more like engine being not adequate for vehicle weight. That is a problem with almost every single car being sold in Europe now. With measly 1.0 or 1.2l engines to pull 2tons of weight. Ridiculous. I assume that benz engine had turbo if not that was the problem.
If the 240D had turbo, we'd probably still have it. Only the 300Ds had turbo.
 

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I was debating for a long time whether it's worth it making this post but here we are prompted by latest TTWT video.

A beautiful custom setup with this mower and with laser box blade those 2 are something special.
However it was mentioned that tractor seemed happier PTO rpm wise when at slightly lower engine rpm. I very rarely use full rpm on my tractor and any other diesel equipment. There are several reasons why.
Firstly diesel engine usually provides maximum torque and power at much lower rpms when compared to gasoline engine. This is the same for engine in our 4052R which I will get back to later.
Passive regen is one hell of a mystery on these machines but from what I read it happens when engine is working in its optimal power window. From what I observer over hundreds hours of field work is that passive regen usually happens around 2100-2200 engine rpm when using taxing implement. Think mowers, baler, ground engaging stuff. When using higher rpms sooth build up was higher when compared to using lower rpms than 2100.
Lastly every time I we were given guidelines by our dealer on how to operate any implement we were always told to keep engine rpms in moderation. From my experience there is really no need for pushing 540. I have not noticed any difference while mowing, tilling, baling, wood chipping,... We even have some implements that suggest running specifically at 450 PTO rpm, not higher, that translates roughly to 2100-2200 engine rpm range.

When our tractor was at dyno what I really wanted to see was the torque and power curve. Here is the partially translated version with some personal information removed but should be sufficient to further my case.

4052R stock engine is represented by dashed line. As can be (not so clearly) seen maximum power is available at roughly 2100 engine rpm.

I am using this post mainly as callout to @Tractor Tim . Would it possible to show these power curves from your dyno measurements? Comparison of both stock and turbo 1R engines might have drastically changed them as well. (Using this method as I hope it will work unlike YT comments and might be beneficial for others.)
I would also like to see dyno power and torque curves of other models and engines if you guys have them available and anything else that might be added to this topic.

By no means I am saying that these engine can not run at full rpm. I am simply suggesting there is basically no good reason to do so.
The manual for my tractor says that the engine can be run at full load between the engine speed for 540 PTO RPM with economy PTO engaged (just shy of 1600 RPM) and the engine speed for 540 PTO RPM with regular PTO engaged (just under 2100 RPM.) Full throttle is 2200 RPM. The only time I run it completely wide open is when roading the tractor, for the extra mile per hour of road speed. The only PTO driven implements I use at less than 540 PTO RPM are a PTO driven broadcast spreader in some situations (the PTO speed controls the broadcast distance) and the posthole auger, which is only supposed to be run at about 300 PTO RPM according to the manual. Everything else gets run at 540 RPM, and since my transmission does not have the option to have the economy PTO, it's 2100 engine RPM. I'd guess the tractor is running at 2100 engine RPM about 2/3 of the time as most of the time I am a cutter, mower, tiller, square baler, generator, etc. that is supposed to be run at 540 PTO RPM. The generator MUST be run at 540 PTO RPM or the frequency and voltage are off. The others I run at 540 RPM as their capacity decreases with decreasing PTO RPM down to a certain point, and then below that performance just stinks (particularly mowers.) I just maximize ground speed at full PTO speed rather than throttle back to decrease PTO speed as I get done faster. Also, the power peak on my engine appears to be close to the full PTO speed, so being at a lower RPM than that results in being bogged down if I hit a heavier spot with a more power-hungry implement rather than having the engine RPM pull down a smidge and power through it.

I don't have the Bluetooth dongle to check soot level on a cell phone but my tractor does an active regeneration cycle exactly every 100.4 hours. There is supposedly a maximum engine hour interval between active regenerations and since it is so consistent with the regenerations, I suspect I am hitting the hour limit rather than a soot load limit so what I am doing is fine.

I don't have the full power curve for my engine but Deere says it makes a peak 74 HP at 2100 RPM and makes peak torque of 224 ft-lb at 1600 rpm (68 HP.)
 

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I agree with @mo1 to run the tractor at PTO speed for those implements that need it. The reason is that is how the implements are designed to run, if you run at 450rpm you are running 17% slower. When in heavy grass, 3' to 5', you will want to be at 540rpm and can bog down in heavier spots.

Like I said in post #5 you want the rpm to above the maximum power because the governor alone is going to do the job, you want more power available at a lower rpm so you don't stall.

If you have a 4052R you can get an economy PTO kit for it which lets you run an implement at 540rpm at a lower engine rpm
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As @Vern3039r said - The implements are designed to run at their designed speed.

It was mentioned above that diesel engines "generally" make the most torque at lower RPM. Something to consider - The engines are selected/designed/engineered for their specific use case in the device they are mounted. Thus the PTO speed of 540 on a 1 series is 3200engine RPM, but a 4052 has a much lower engine speed at 540PTO.

These engines and their mated transaxle have been engineered to operate in their designed operation window and it would be silly to think that running in the specific window it's designed to run in for is bad for it.

By the same logic, running a large displacement tractor trailer engine designed to run between 1200-1500RPM at 1000RPM would be "better" cause diesels generally make torque at lower RPMs. Engine design determines its best operating window and its relative to the engine use case.

I mow at WOT, so when the load (mower blades and drive) exceeds available power, the blade tip speed remains high. How you run your equipment- That's up to you 😁
 
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Not sure how common it is in other models but when I was playing around with different pulleys on my finish mower I discovered the tach acuracy on my 4310 was way off.

I purchased a inductive tach to check and verify engine and PTO speeds. I am still running my machine at or near the PTO mark on the tach but it is actually much slower than 540 at that line.

To get my PTO to 540 my tractor tach was reading over 3000 RPMs. Reading engine speed at the flywheel and comparing to PTO, 2650 at the flywheel produced a reading of 554 RPMs at the PTO with the inductive tach.

At a tach reading of 3000 RPMs my actual engine speed was 2460. Belt tension is correct with a new belt and the mechanical temperature gauge I installed reads right at the thermostat rating of 160F so the alternator SHOULD be spinning at the correct speed.

The bottom line is when I am indicating 2700 RPMs on the factory tach my ACTUAL PTO speed is 463 RPMs.
 

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Discussion Starter · #16 ·
I agree with @mo1 to run the tractor at PTO speed for those implements that need it. The reason is that is how the implements are designed to run, if you run at 450rpm you are running 17% slower. When in heavy grass, 3' to 5', you will want to be at 540rpm and can bog down in heavier spots.

Like I said in post #5 you want the rpm to above the maximum power because the governor alone is going to do the job, you want more power available at a lower rpm so you don't stall.

If you have a 4052R you can get an economy PTO kit for it which lets you run an implement at 540rpm at a lower engine rpm
View attachment 854756
I have that kit on order since approximately may 2021. I would love to finally get it but it seems JD is just totally ignoring it.

When I use 450rpm pto while mowing only slight bogging down occurs even in heavy wet thick grass. When I use higher rpms engine bogs down much more. I tried side by side cuts with no difference in final cut and mulching.
 

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Discussion Starter · #17 ·
As @Vern3039r said - The implements are designed to run at their designed speed.

It was mentioned above that diesel engines "generally" make the most torque at lower RPM. Something to consider - The engines are selected/designed/engineered for their specific use case in the device they are mounted. Thus the PTO speed of 540 on a 1 series is 3200engine RPM, but a 4052 has a much lower engine speed at 540PTO.

These engines and their mated transaxle have been engineered to operate in their designed operation window and it would be silly to think that running in the specific window it's designed to run in for is bad for it.

By the same logic, running a large displacement tractor trailer engine designed to run between 1200-1500RPM at 1000RPM would be "better" cause diesels generally make torque at lower RPMs. Engine design determines its best operating window and its relative to the engine use case.

I mow at WOT, so when the load (mower blades and drive) exceeds available power, the blade tip speed remains high. How you run your equipment- That's up to you 😁
I do not think that running at designated 540rpm is bad. Ofc I know that the whole tractor was designed around that. But I still do not understand why the most power is not provided at that or around that rpm range.
Also why passive regen does not happen at that range but instead sooth build up is increased.
 

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Full rpm on a tractor is somewhere about 3000 rpm. The Benz diesels of old revved to 4,300 rpm and could run there all day long. The VW TDI revved to 5,000 rpm.
It depends on the engine. Most of Deere's current diesel engines have a rated speed of 2100-2200 RPM and redline is 100-200 RPM above that. Most of their >2 cylinder engines in the past were in the 2200-2500 RPM range, and the old Johnny Poppers ran between 800 RPM and the mid-1000s RPMs.
 
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