L2501 tuned down...? Dealer stated...?

WRG1115

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L2501
Oct 19, 2021
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SW VA
I purchased a 2016 L2501 Geared 4x4 recently and while picking up a few accessories at the dealer, I was asked what I thought of the tractor. I have been a MF man for years so they all thought it curious when I bought this one used. It only had 22 hours on it when I bought it and it was more than five years old, garage kept in a heated garage and came with backhoe and loader. I upgraded to a SSQA plate, added an awning and installed a third function as well as a few little things more. I told them so far, it had done all I had asked of it, except it struggled a bit on the PTO attachments. The manager said that since I was no longer under warranty I should consider tuning it back up to where it was made to run optimally. I was curious and mentioned I had read about that in a few places including here on a two year old post that reads as though it got out of hand. He laughed. I am a mechanical guy and have had extensive carriers in mechanical engineering of various facets, so I asked the obvious. If the tractor was designed, built and sold as a 25 HP, isn't that its optimal output? He stated the L2501 was tuned down to get under 26HP and that he has heard many Kubota conversations pertaining to owners tuning them back up. That it is safe and more productive when operated as such.

SO...has anyone done this? If so, what exactly did you do and what have you seen as a difference?

Please, this is not a debate on whether it should be done, can be done, or whatever....I am asking to see if anyone has actually made this modification as multiple dealers nationwide have agreed that it is tuned down and can be tuned up but due to liabilityies etc....they can not direct on how. So, anyone?
 

jimh406

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Kubota L2501 with R4 tires
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There are a few people that have pushed the RPMs higher. It’s pretty simple. You do have to cut the wire that holds the screw in place. Also, there is one guy at least who added a turbo. No, there isn’t a lot of people doing this type of work, but there are some. Also, there are some that are modifying the pressure valve to lift more.

People have said the L2501 is a 30 plus engine from the past. Compared to other models, it seems it could easily produce more HP with the displacement it is.

I have a 2021 with 63 hrs. I’m not doing anything to mine, but at the same time, it’s under warranty.
 

lugbolt

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nope. It IS made to run where it's designed, right from the factory. If it were designed to run 3000 rpm and make 35 hp, it would make that from the factory.

There are LOTS of changes needed if you plan on turning it up, and honestly it's a lot more involved than just turning any screws. The information is not available, nobody publishes it (correctly)--I know the differences but I'm not at liberty to give that information out.

simply turning a screw will drastically increase your egt and particulate emissions.
 
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1badDart

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Is detuning something that Kubota is known for? In a way it makes sense, they could use the same engine over several models and just change the tune for the target HP class.

Looking at Kubota's web site my M6060 has the same exact engine as the M7060. The M6060 is rated at 64/56hp and the M7060 is rated at 71/64hp.

A friend of mine had his M7060 turned up at our local dealer. I asked if he could tell a difference and he said "it runs faster on the road". I don't see me having my M6060 turned up, so far it has had plenty of power. Traction/weight? No.
 

jimh406

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Kubota L2501 with R4 tires
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nope. It IS made to run where it's designed, right from the factory. If it were designed to run 3000 rpm and make 35 hp, it would make that from the factory.
That is obviously false. There are lots of reason why they would detune including having a super reliable engine and having an engine that will fill the non emission segment for the same size tractor.

Also, there is no way for you to predict how much polution it would/would not cause by turning screws. We aren’t talking about a gasoline engine afterall.
 
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ItBmine

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That is obviously false. There are lots of reason why they would detune including having a super reliable engine and having an engine that will fill the non emission segment for the same size tractor.

Also, there is no way for you to predict how much polution it would/would not cause by turning screws. We aren’t talking about a gasoline engine afterall.
Yep, just like class 8 truck motors. The same engine can be rated for 400 to 600 horsepower. It's all about what you need for the application.
 
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GeoHorn

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The engine in my M4700 (51hp) is the same one in the M5400 (58hp) except for the fact the M5400 runs 100 RPM faster governed speed…. A simple-minded answer would suggest that by adjusting the overspeed governor UP 100 RPM would allow it to put out the 58hp of the M5400.

But lugbolt is telling it right….. there are other subtle differences… and one not-so-subtle…
The M5400 engine also has a turbo to allow it to suck in enough air to boost compression that is not available to the M4700 even at the higher rpm limit…. so the M4700 engine turning the same rpm will not actually perform the same work as the M5400 engine despite their basic identicality.

You don’t get something for nothing.

WRG… Your dealer would have no lost sleep if you ruined your little tractor and he could sell you a replacement with more HP. Don’t listen to him. (and, assuming he is technically savvy about the actual differences between the two versions of engine….which I doubt….he’s disingenuous for suggesting it.)
 
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rgOO6

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Kubota L2501DT
Sep 12, 2021
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Villa Rica, GA
Definitely will be following this post. I do not need anything more out of my L2501DT cause it does everything just fine, but boosting it looks incredibly fun. Just to restate the caution others have said above (I have done engine timing when I raced cars), you need to be really careful. Engine timing is set for many different reasons, and fuel flow and air mixture can be really important. Leave it a bit rich if you need to. Extra fuel can help cool the engine but running with too much air can cause really hot combustion and burn holes in metal. Don't just depend of someone else having done it before. Manufacturers test engines extensively to fine tune reliability. The only reason I actually think this engine can be boosted is emissions. Oddly enough, Japanese companies have a history of detuning engines for a variety of reasons... (cough cough, Nissan.... ).
 

North Idaho Wolfman

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There is more to tuning (turning up) a mechanically injected engine than a simple turn of a screw to increase RPM.
 
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DaveFromMi

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For re-tuning, I think you just advance the injection timing. What is the current timing and what is the recommended timing?
 

lugbolt

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remember kubota has to meet emissions laws too. That includes particulate matter (PM), CO2, NOISE, NOX, among many other compounds. The L2501 meets tier 4 standards for sub 25hp diesel engines.

When you increase the power output, you are now above the 25hp threshold, and thus technically are breaking the tier 4 emissions reg because you have tampered with it's emissions output.

turning "the screw" tampers with how much fuel is allowed into the engine...thus increasing HEAT (and no additional airflow), PM, possibly noise, NOX, CO, CO2, etc. And since Kubota does not and will not give out a specification as to where the screw is to be set, you have no idea where you started or where you're going. Screw it in or out? That is, the question. And what are the risks?

Indirect injection engines are kinda sensitive. They're not nearly as easy to make power than a direct injected (or better yet DICR) engine that has forced induction, and that's an area I see forum people arguing about often. The amateur train of thought here is that " I done put a programmer on my pick em up truck and it go faster"....and that's true, but it's also a completely different style of engine.

the engine can make quite a bit more power, but you also gotta remember it's application. L2501 is a sub 25hp tractor, and it's original thought was to take advantage of the 25hp threshold for the dpf, and that has been it's success. But it's underpowered, people buy it because they're scared of the dpf on the 3301/3901/3302/3902 based on all the internet horror stories between those and trucks. Then they get it home, start asking it to do things that a 3301 does easily, and it becomes "weak". Next thing, get online and search "how to make more power out of L2501", and some just say it's as easy as turnin a screw which isn't entirely true--there's quite a bit more to it. And we compare teh 2501 to the 3301/3901 because it's basically the same "frame" (sized) tractor. OFtentimes people will say that they share these and those components so they're the same--and that could not be further from the truth. There are, quite possibly, thousands of differences if you dig deep enough! But internet experts that don't work with them on a daily basis will never know this, or more specifically, they'll know less than those who did.

next issue. Transmission. It's designed to run X ground speed at X engine rpm. When you modify the engine, you place more torque on the transmisison, clutch, drive train. Is it gonna take it? And-the L2501 only runs 2200 rpm (IIRC) and the trans is geared so that it has acceptable speeds at that rated engine rpm. When you go cranking it up, now you have a tractor that is uncontrollable at elevated rpm, might go 25 mph in high, but also in low it might very well be way too fast for tractor work--similar to my old 9N, was useless for low speed stuff like tilling, it was just too fast in low/first. HST tractor? Now you put more strain on the HST, it was designed to run at 2200 rpm max, the charge pump may very well be in relief all the time, the main hyd relief may be in relief all the time, the oil gets hot, you can't stand to sit near a trans that operates at 200+ deg all the time, then come back griping about "my transmission runs hot" or "my hst doesn't work anymore why".

egt. When you increase fuel flow into the engine without increasing airflow, your egt will go up. Also when you play with fuel timing, egt can go way up too. How much? Try it and tell us. Maybe it'll last a while. Maybe it'll spit aluminum out of the exhaust pipe. Or maybe it'll be much more spectacular--break a valve off and destoy the entire engine. Please post pictures!!! Better yet video!!

In training many moons ago we played with a little diesel, about 110hp as I remember, the software that we was learning was in it's infancy. We could do a lot with the injection timing and quantity, so I "played". I saw egt over 1500 degrees, the manifold and turbo housing a dull red, really high RPM, knocking, rattling, etc. So it's not that hard to make a change that can really do some damage.

With that in mind, modification is always at your own risk, you (the modifier) assume any and all liability.
 

BAP

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Just because the specs list the same displacement engine in more than 1 model tractor, it doesn’t mean that the engine can’t be set up differently. Timing, injectors, injection pump, cam and so on can be set differently or even different ones used in that same block. Without knowing every little specification about the engine, there is no way of knowing that they are exactly the same.
 

SDT

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Is detuning something that Kubota is known for? In a way it makes sense, they could use the same engine over several models and just change the tune for the target HP class.

Looking at Kubota's web site my M6060 has the same exact engine as the M7060. The M6060 is rated at 64/56hp and the M7060 is rated at 71/64hp.

A friend of mine had his M7060 turned up at our local dealer. I asked if he could tell a difference and he said "it runs faster on the road". I don't see me having my M6060 turned up, so far it has had plenty of power. Traction/weight? No.
"All" manufacturers do this and have for decades.

SDT
 
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SDT

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multiple and various
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nope. It IS made to run where it's designed, right from the factory. If it were designed to run 3000 rpm and make 35 hp, it would make that from the factory.

There are LOTS of changes needed if you plan on turning it up, and honestly it's a lot more involved than just turning any screws. The information is not available, nobody publishes it (correctly)--I know the differences but I'm not at liberty to give that information out.

simply turning a screw will drastically increase your egt and particulate emissions.
Agreed.

Increased HP produces more heat. Multiple changes are made to deal with the increased heat.

SDT
 
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DaveFromMi

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L3901, 5' Bush Hog
Apr 14, 2021
157
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Back in my automotive days, Ford decided they needed a V8 in the Explorer. They managed to shoehorn the 302 cu in in the engine compartment, but had to modify (restrict) the exhaust due to lack of room. The result was less powerful engine than the standard V6. Their solution was to detune the V6.
 

1badDart

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Sep 7, 2021
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W. KY.
My buddy with the M7060 didn't mention any "screw turning" said it was done with a computer, as would be expected with a modern computer controlled engine. They do it in pick up trucks and cars every day.
 

ctfjr

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Although I wouldn't try it with my tractor my 'toy' Subaru STI has been modded a bunch. At first just doing computer tuning resulted in modest increases in torque on the dyno. The real improvements came with the mechanical changes - high flow fuel pump, 1000cc injectors (from 750cc), intake cam, larger turbo, new exhaust system, equal length header, etc

Of course with those 'performance changes' came the 'insurance changes': ARP studs, piston upgrade, high flow oil pump, extra large windage oil pan, etc

At least I had some idea of what I as doing with the STI. I'm completely clueless on trying that with the tractor.

btw wheel hp went from 220hp to 335hp