MNVikingsGuy
Active member
Equipment
LX3310, FEL, 60" bucket, 60" grapple, 60" box blade, 60" flail, LX2980 blower,
Optimum Rpm.
- Thread starter Hillbilly7
- Start date
85Hokie
Moderator
Staff member
Lifetime Member
Equipment
BX-25D ,PTB. Under Armor, '90&'92-B7100HST's, '06 BX1850 FEL
Wide Open Throttle.
On governed engines (lawnmower, rototiller, all diesels...etc) WOT will be limited to the maximum operating RPM. It is not possible to overrev the engine with throttle control.
You need to run it at wot to keep the hydraulic fluid cool and moving, wot on my B is the PTO rpm, it won't go any higher so you have to run it wide open just to meet the requirements of the PTO.
That is what governors are for, the engine is not running as fast as it can it is being governed down to run the implements hooked to the tractor.
I do run my engine at lower rpms when not working it hard.
PS: never idle or run a diesel at low rpm while working they don't like it.
My 1950 john deere B idled at 1200 and wide open it ran 1500 of course it was gas. Ha!Ha!
My neighbor had a JD tractor to farm his 500 acres and kept blowing injectors right out of the head, after doing this many times JD sent a field mechanic down to see what was going on, and found out he was running the engine too slow building up condensation and blowing the injectors, he was told to start the tractor allow a high idle warm up then do not reduce the throttle below wide open until he was done plowing or disking, he did this and never had another problem and that tractor never ran better.
Of course on the farm we used tractors we didn't do light work too much, I had two hundred acres and used a Massey Ferguson diesel.
That is what governors are for, the engine is not running as fast as it can it is being governed down to run the implements hooked to the tractor.
I do run my engine at lower rpms when not working it hard.
PS: never idle or run a diesel at low rpm while working they don't like it.
My 1950 john deere B idled at 1200 and wide open it ran 1500 of course it was gas. Ha!Ha!
My neighbor had a JD tractor to farm his 500 acres and kept blowing injectors right out of the head, after doing this many times JD sent a field mechanic down to see what was going on, and found out he was running the engine too slow building up condensation and blowing the injectors, he was told to start the tractor allow a high idle warm up then do not reduce the throttle below wide open until he was done plowing or disking, he did this and never had another problem and that tractor never ran better.
Of course on the farm we used tractors we didn't do light work too much, I had two hundred acres and used a Massey Ferguson diesel.
[Q
[/QUOTE]
Wide open throttle (WOT) is a throw back from spark ignition engines where the power is controlled by airflow with a throttle plate.
In a normally aspirated diesel engine, the intake is always unrestricted and power is controlled by fuel flow. The optimum rpm is dependent on the work being done. If you are plowing, you use the maximum rpm that allows you get the plowing done at the rate you need to. For some it maybe full max power, for others it may be optimum fuel economy, or minimum cost. It becomes the operators choice.
Those power, torque, and BSFC curves as a function of rpm are derived from testing where an rpm is held constant and load applied until a certain smoke number is measure in the exhaust indicating there is not enough oxygen in the fuel charge to completely burn all the fuel. (In the old days that was when you saw black smoke. These days it is smoke determined by smoke number.) So those curves represent the maximum power available at any given rpm.(Note: Rated rpm does not mean rated power. You can have the transmission and pto in neutral and rev the engine to max rpm and you will be at the minimum power for that rpm. You only obtain rated power at rated rpm when you are under load.)
Now along comes Tier IV. ( which I believe is the stupidest regulation ever conceived for farm equipment) and you either have to run at max rpm and power to keep the DPF clean or be subject to DPF regeneration. Along with this comes added initial cost, reduced reliability, and increase operating cost with no significant gain air quality or fuel usage. Like I said, dumb!
The power required for any given work operation is determined by the implement you are using and the speed at which you are using it. If the implement does not require max power to get the job done you are doing than the engine can be run at the same rpm but lower fuel flow.
I was always told to run at the minimum rpm and speed that gets the job done. That's what works for me.
P.S. I have no Tier IV equipment.
[/QUOTE]
Just some thoughts on this topic of optimum rpm.
Wide open throttle (WOT) is a throw back from spark ignition engines where the power is controlled by airflow with a throttle plate.
In a normally aspirated diesel engine, the intake is always unrestricted and power is controlled by fuel flow. The optimum rpm is dependent on the work being done. If you are plowing, you use the maximum rpm that allows you get the plowing done at the rate you need to. For some it maybe full max power, for others it may be optimum fuel economy, or minimum cost. It becomes the operators choice.
Those power, torque, and BSFC curves as a function of rpm are derived from testing where an rpm is held constant and load applied until a certain smoke number is measure in the exhaust indicating there is not enough oxygen in the fuel charge to completely burn all the fuel. (In the old days that was when you saw black smoke. These days it is smoke determined by smoke number.) So those curves represent the maximum power available at any given rpm.(Note: Rated rpm does not mean rated power. You can have the transmission and pto in neutral and rev the engine to max rpm and you will be at the minimum power for that rpm. You only obtain rated power at rated rpm when you are under load.)
Now along comes Tier IV. ( which I believe is the stupidest regulation ever conceived for farm equipment) and you either have to run at max rpm and power to keep the DPF clean or be subject to DPF regeneration. Along with this comes added initial cost, reduced reliability, and increase operating cost with no significant gain air quality or fuel usage. Like I said, dumb!
The power required for any given work operation is determined by the implement you are using and the speed at which you are using it. If the implement does not require max power to get the job done you are doing than the engine can be run at the same rpm but lower fuel flow.
I was always told to run at the minimum rpm and speed that gets the job done. That's what works for me.
P.S. I have no Tier IV equipment.
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Great info here on rated and max rpm, guys. I did get hung up for a while because my Kubota manual writer is so terrified of full throttle.
Once it's warmed up, I run the engine in the rated rpm red notch, about 2,800. I still have not pushed the throttle wide open! But I think it is barely beyond the rated rpm and wouldn't hurt the engine a bit.
Should I run the tractor wide open for a while close to the end of the break-in 50 hours? A good place to do this would be when I run down to the corner fuel station. Tractor is under no load and on smooth, easy pavement.
Once it's warmed up, I run the engine in the rated rpm red notch, about 2,800. I still have not pushed the throttle wide open! But I think it is barely beyond the rated rpm and wouldn't hurt the engine a bit.
Should I run the tractor wide open for a while close to the end of the break-in 50 hours? A good place to do this would be when I run down to the corner fuel station. Tractor is under no load and on smooth, easy pavement.
nbryan
Well-known member
Equipment
B2650 BH77 LA534 54" ssqa Forks B2782B BB1560 Woods M5-4 MaxxHaul 50039
I never use WOT.
I set my tractor's indicated operating rpm to 2500 rpm for full-pto speed equip like bush hogging, wood chipper, snow blowing, backhoe operation.
I'll run around 1800-2200 for tooling around with the loader and forks kind of work.
So, it depends on what's hooked up and what I'm doing.
But never have needed WOT, which climbs to around 2800 rpm if I set the throttle to max.
I set my tractor's indicated operating rpm to 2500 rpm for full-pto speed equip like bush hogging, wood chipper, snow blowing, backhoe operation.
I'll run around 1800-2200 for tooling around with the loader and forks kind of work.
So, it depends on what's hooked up and what I'm doing.
But never have needed WOT, which climbs to around 2800 rpm if I set the throttle to max.
So it's not an aspect of break-in to run WOT? I'd gotten the impression some feel it's important to seat the rings or something.
I would think that LOADING the engine (at appropriate RPM) is far more important to get the rings to seal during the break-in process.
Lets think about what break-in really is:
All the moving parts within the engine have just met each other. Microscopic high-spots will wear off in the initial 5-10 hours of running. (bearings, gears, seals.... etc) The ENGINE OIL suspends this metal grit and the filter removes the larger chunks.
The piston rings continue to hone themselves against the cylinder-walls for some period of time. As these sliding components break-in, the engine compression continues to go up. Well sealed rings respectively help the engine make more power using less fuel.
At some point, the cylinder walls are said to "glaze". After that, measurable increases in engine compression are no longer seen. No more ring-sealing happens. It should be obvious that maximum MPG is a reflection of using the least fuel to generate the most power out of the crankshaft. Is this not the very purpose of an ICE?
ICE = Internal Combustion Engine
-------------------
Knowing the above.... it should be obvious that we want the BEST seal before glazing happens.
To encourage ring-sealing, LOADING of the engine pushes the rings against the cylinder walls and encourages ring-sealing.
This is EXACTLY why it is said with an over-the-road vehicle that "Occasional bursts of full-throttle acceleration" help seal the rings. The periods of running between these loading events allows the engine oil to carry away microscopic shavings and remove heat from the rings/cylinders.
Folks who MEASURE engine-compression in relation to break-in have documented the above time and again. These facts are only disputed by those who do not fully understand the break-in process.
I can tell you from automobile perspective, it takes about 30K miles before maximum MPG is measured. After that, my MPG numbers level out for the life of the vehicle.
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nbryan
Well-known member
Equipment
B2650 BH77 LA534 54" ssqa Forks B2782B BB1560 Woods M5-4 MaxxHaul 50039
My 1st 50 hrs I "took it easy" and only ran in that mid range 1800-2200 m oist of the time, but also worked it hard a few times for a minute or 2 at OPERATING RPM not WOT. It was winter when I got the tractor so ran around 2200 with the blower and moved along mostly slowly not loading it up too much, then to 2500 and made it grunt for a bit, then throttle back again and slow a bit for a while.
Brand new I was real nice like that. Near the end of the 50 hours there wasn't any more babying going on.
Jasonized
Active member
Lifetime Member
Equipment
L3902, LA526, box scraper, grapple, pallet forks, tree ripper, lane shark 3
i know this is an old post, but ... most of the small kubota tractors on here are NOT turbocharged like we're used to these days. Obviously a turbo'd engine will deliver much more low end power and torque. Even tho they are diesels, without the turbo they aren't the same as most modern diesels ... they need rpm's to get work done.
If you look at the hp/tq curve on a b2601 engine (D1105 series) you will see that between 2650 and 2800 the hp is the same.
But the torque is higher at 2650 than 2800. Fuel consumption is less too.
I run my engine 2600-2700 rpm when mowing.
No complaints from the tractor.
But the torque is higher at 2650 than 2800. Fuel consumption is less too.
I run my engine 2600-2700 rpm when mowing.
No complaints from the tractor.
fried1765
Well-known member
Equipment
Kubota L48 TLB, Ford 1920 FEL, Ford 8N, SCAG Liberty Z, Gravely Pro.
nbryan
Well-known member
Equipment
B2650 BH77 LA534 54" ssqa Forks B2782B BB1560 Woods M5-4 MaxxHaul 50039
Rated rpms for pto usage 540rpm rear and 2500rpm front, when pto in use. 540 rear pto is about 2450rpm engine rpm, 2500 front is 2500 engine rpm. When using backhoe I run at 2500rpm.
My B2650 manual states 2500 rpm for "rated" HP output, so I don't run it past 2500.
When doodling/working with bucket/forks etc it depends on the task. Minimum I set rpm for is about 1500, for light slow work, delicate maneuvers, etc. Steady loader scooping and hauling/dumping 1800-2300rpm. That range will do most jobs well, but up it goes to 2500 if there's a really heavy load to raise and haul, or heavy drag on ground-engaging implements.
I NEVER WOT, which means the throttle lever is punched all the way open max. Why push 2600-2700rpms when the engine is made to work the best at 2500?
Yes but for some WOT is the incorrect spelling…in some circles, it’s spelled WFO.It fits, doesn't it?