L2501 Turbo: A Journey Defined - The tractor, The comparison, The modification, The results...

Rdrcr

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The L2501 Turbo design, fabrication, installation and testing has been added to Post #4, #5, #6 and continued on Post #22.

Man, I was sure hoping I could get all the content in the first 6 posts....that didn't happen...

Mike
 
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Rdrcr

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(continued from posts #1-6)….

My testing parameters are flawed.

Luckily, a forum member reached out to me with a remedy. He suggested to run the tractor up to an unmovable object to create a heavy load on the tractor. Ahhh, that makes sense! He also suggested adding even more fuel. Done! In addition to his suggestions, I decided to add a new test too. Going up my hill in (H) gear carrying a load! Two new tests! Let’s see what we have now. The results came pouring in!

L2501 HST 4WD (LA525 Loader w/ 66” QA Bucket, Liquid Tire Ballast) - TURBO SYSTEM - 9 PSI - Fuel Setting, 2 Full Turns (64* ambient temperature).

Recorded EGT’s:
Idle = 250-300*
Traveling on flat ground (M) = 300-500*
Loader and grading work (M) = 500-680*
Traveling up hill carrying medium load (22* Slope, 40% grade) (M) = 500-640*
Traveling up hill carrying medium load (22* Slope, 40% grade) (H)= 500-779*
Immovable object = 985*
Peak EGT = 985*

More is better. I increased the fuel volume to 2 1/4 turn, counter clockwise. This setting resulted with 10 PSI peak and 8 PSI sustained boost pressure. There is some smoke observed at startup and a puff or two during operation, but there is no visible smoke under full load. In all seriousness, the tractor is begging for even more fuel. I swear there’s more boost pressure and more power to be unlocked. No doubt. However, we’re recording just over 1000 degrees peak EGT and that’s right where I want to be and that’s as far as I’m going (for now).

L2501 HST 4WD (LA525 Loader w/ 66” QA Bucket, Liquid Tire Ballast) - TURBO SYSTEM - 10 PSI - Fuel Setting, 2 1/4 Full Turns (78* ambient temperature).

Recorded EGT’s:
Idle = 250-300*
Traveling on flat ground (M) = 300-500*
Loader and grading work (M) = 500-730*
Traveling up hill carrying medium load (22* Slope, 40% grade) (M) = 500-650*
Traveling up hill carrying medium load (22* Slope, 40% grade) (H) = 500-812*
Immovable object = 1,033*
Peak EGT = 1,033*

Overall, I’m very pleased with this setting and the performance I’m feeling. The L2501 Turbo, is awesome!

Whatever bro. EGT measurements, testing and comparisons blah, blah, blah, blah, blah.
Are there any performance gains with the Turbo installed? Does the tractor work better? Can it do more stuff?

It’s gonna be a minute before I can get my tractor to a PTO dyno. However, I can share the perceived gains I’ve experienced with the Turbo system installed.

Initially, I was expecting more overall performance. I assumed the tractor would behave similar to a car or truck equipped with a Turbo and would produce additional power in all working conditions, even without a load. But, that’s obviously not the case as illustrated with the final EGT tests. The tractor has to be under heavy load for the Turbo to really function. So, while driving and operating the tractor in normal conditions, you really can’t feel any difference. Literally, 90% of the time doing minor tasks, it feels like a completely stock L2501, which isn’t a bad thing. But, when you need power, it’s there!

L2501 vs Hill.

First and foremost, having the ability to carry heavy loads up my big hill in (M) gear was an important consideration for improvement and a specific task my tractor continually struggled with incessantly. With the Turbo installed, the L2501 has zero issues carrying a heavy load up this hill in (M) gear. At 2,200 RPM the tractor maintains speed and boost pressure all the way up and over the hill. The RPM’s remain constant and the L2501 absolutely refuses to bog down regardless of the load it’s carrying. It’s a relief knowing I no longer have to crawl up this hill. With (M) gear functioning to my expectations, (L) gear is no longer needed. My L2501 Turbo has conquered the big hill and that makes me a very happy operator.

Pushing the envelope, I decided to run my tractor up my big hill carrying a load in (H) gear. In all seriousness, this was a stupid test (but necessary). The path up the hill isn’t made for speed. It’s uneven and rocky. Trying to go fast isn’t wise. But, I had to give it a shot. For the first time ever, the tractor was able to climb the hill in (H) gear. But, it wasn’t pretty, about halfway up the hill, the Turbo dropped boost pressure, the tractor bogged down and I lost speed and momentum. Regardless, the tractor didn’t give up and it made it to the top of the hill to deliver a load of large branches to my brush pile. In (H) gear? That’s a first! Nemesis no more! The L2501 Turbo is a beast!

Another important consideration was transportation speed in (H) gear. I’m pleased to report the L2501 Turbo can maintain ground speed on flat and hilly paved surfaces and I have full use of (H) gear for transportation purposes. The tractor hilariously takes off rapidly from a stop and accelerates to top speed almost instantly and continues to maintain speed without issue. The tractor shows no sign of bogging down. The Turbo will immediately deliver 9-10 PSI and slowly taper off to 5-6 PSI because the load drops off very quickly after take off. There’s just not enough load without doing actual work to sustain boost pressure.

The L2501 Turbo powers my wood chipper in heroic fashion. During my testing, the tractor didn’t bog down once and it chipped everything I could stuff down the shoot, including whole saplings. There’s some serious power coming from the PTO, it is performing exceptionally well.

Overall, I have not logged nearly enough time on the Turbo system to provide any full conclusions. So, those revelations will come in time. What I can say is that I added the Turbo system to produce more power in challenging conditions. It has in fact delivered.

I know at the end of the day, most of us aren’t in a hurry to get our tractor work done quickly. Our tractors and the work we do with them, is our therapy.
However, I know there are times, when I’ve been on the tractor all day long and it’s starting to get late. The sun is beginning to set and I only have a few more buckets of material to move, a couple more brush piles left to transfer, a small pile of branches left to chip, an acre left to mow, a half acre left to grade, or a quarter acre left to till, a little more power and a little more speed wouldn’t hurt.
Thankfully, I have an L2501 Turbo to do the job.

Sometime in the near future, when the opportunity presents itself, I will be putting my L2501 on the PTO dyno to finalize the results and testing of my L2501 Turbo system. Until then, we’ll continue discussing; the Tractor, the Comparison, the Modification and the Results.

Thank you for reading.

Mike
 
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drewzee87t

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Really nice work and that kit should sell well. Anyone in high desert or rocky mountains would need one, and anyone that just likes to have more power, would want one.

I love turbos, all my cars are turbos, my kubota is turbo. The PTO difference is amazing when you can get to doing work with it. All the other pushing and going up hills and stuff is just loading the hydrostat up to its' relief pressure.

So you might look into that pressure relief if you want to burn rubber or go fast. I haven't monkeyed with my pressures because I love my baby and there's really no where that I would want to go that fast on a tractor of this size :). You can adjust the hydro to make more power to the wheels.
 
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Rdrcr

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Really nice work and that kit should sell well. Anyone in high desert or rocky mountains would need one, and anyone that just likes to have more power, would want one.

I love turbos, all my cars are turbos, my kubota is turbo. The PTO difference is amazing when you can get to doing work with it. All the other pushing and going up hills and stuff is just loading the hydrostat up to its' relief pressure.

So you might look into that pressure relief if you want to burn rubber or go fast. I haven't monkeyed with my pressures because I love my baby and there's really no where that I would want to go that fast on a tractor of this size :). You can adjust the hydro to make more power to the wheels.
Thank you!

I can't wait to begin some projects with the tractor and log more hours on the Turbo. I'm definitely pleased with what I'm seeing now!

That's some interesting info on the hydro! :D

Mike
 

drewzee87t

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I am at about 150 hours on the turbo on my 2910. TD025 off kubota donor probably same/similar wheels. Tractor runs better than ever and makes a lot of power.
 
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tractorX

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KUBOTA L2501 DT 5' BOX BLADE 42" FORKS PIRANHA TB 5' BUSH HOG 6' GRADER
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WOW... very impressive!
this wasn't one of those "just slap a turbo on it" mods.
so much R&D went into this modification, outstanding work!
 
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Rdrcr

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WOW... very impressive!
this wasn't one of those "just slap a turbo on it" mods.
so much R&D went into this modification, outstanding work!
Thank you!

Nope. We definitely put a lot of work into the Turbo system. With regular maintenance and normal use we expect it's going perform extremely well for years and years to come!

Mike
 
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PoTreeBoy

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I know Rdrcr has stated he's limiting his mods to the turbo. But, what would be required to let that engine rev to 2600-2700 RPM like the L3301?

I compared the parts in the PTO train, and it looks like PTO speed could be matched by replacing two gears (talking about the HST model here).

I'm not sure about the wheel speed. I didn't follow that out.
 
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JohnDB

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Thank you!

Mike
And thank you for a very interesting set of posts. I'm interested in the cooling system load, is the exhaust temp pyrometer a good indication of cooling system temperature or have you also been monitoring coolant temp separately?
 
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Rdrcr

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I know Rdrcr has stated he's limiting his mods to the turbo. But, what would be required to let that engine rev to 2600-2700 RPM like the L3301?

I compared the parts in the PTO train, and it looks like PTO speed could be matched by replacing two gears (talking about the HST model here).

I'm not sure about the wheel speed. I didn't follow that out.
It’s simple to increase the RPM limit. You would just need to adjustment to the RPM set screw.
Mikemoto17 is operating his L2501 at 2,650 RPM’s. I believe the D1703 is rated at 2,700 RPM’s in other applications.

Good info on the PTO train!

Mike
 

PoTreeBoy

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It’s simple to increase the RPM limit. You would just need to adjustment to the RPM set screw.
Mikemoto17 is operating his L2501 at 2,650 RPM’s. I believe the D1703 is rated at 2,700 RPM’s in other applications.

Good info on the PTO train!

Mike
It's rated 35.1 HP @ 2,700 RPM in the L35. That's a late '90's era with IDI.
 
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Rdrcr

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And thank you for a very interesting set of posts. I'm interested in the cooling system load, is the exhaust temp pyrometer a good indication of cooling system temperature or have you also been monitoring coolant temp separately?
You’re welcome!

I am monitoring coolant temperatures unscientifically via the factory temperature gauge. I have not witnessed any increase in temperatures since the Turbo had been installed.

It’s my understanding that the coolant temperature will follow EGT’s but at a much slower rate. It’s is also my understanding that the L2501 has a very robust cooling system and easily has enough capacity to handle any additional heat caused by the higher combustion temperatures.

None of the other L2501 Turbo setups have had any cooling issues.

Mike
 
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JohnDB

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You’re welcome!

I am monitoring coolant temperatures unscientifically via the factory temperature gauge. I have not witnessed any increase in temperatures since the Turbo had been installed.

It’s my understanding that the coolant temperature will follow EGT’s but at a much slower rate. It’s is also my understanding that the L2501 has a very robust cooling system and easily has enough capacity to handle any additional heat caused by the higher combustion temperatures.

None of the other L2501 Turbo setups have had any cooling issues.

Mike
Mike, I love what you are doing. Very professional, well thought through.

I had been wondering about pistons melting too (some turboed diesels use a jet of engine oil to the undersides of pistons to cool them) but I think you've covered all that with the above explanation. Nice job!
 
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Rdrcr

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Mike, I love what you are doing. Very professional, well thought through.

I had been wondering about pistons melting too (some turboed diesels use a jet of engine oil to the undersides of pistons to cool them) but I think you've covered all that with the above explanation. Nice job!
Thank you!

For the reason you mentioned is precisely why we installed a mandatory EGT provision in the Turbo adapter. It’s highly important to monitor the EGT’s and tune the engine correctly, keeping EGT’s under 1,200 degrees therefore maintaining manageable combustion temperatures.

It starts getting scary when folks are attempting to tune their engine by site, smell and feel. That’s a recipe for disaster.

Mike
 

ve9aa

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rdrcr; even though it's doubtful I'd ever install a turbo I really enjoyed your posts, details and humour.

The only thing I found confusing; and maybe you realized this (or not) was you generated a few empty posts as placeholders, so when I checked back every few days or so, the forum software knows where I've last been and takes me to the last post I have not seen. (generally a few posts by others or maybe yourself) and not really the last edited post.

I can understand you wanted all the info in the first few posts....and I'm not complaining...I found it interested, but it may throw a few folks off the scent of the meat an potatoes if they are not aware of how that was all written. (I detected a sniff of that already by one or two folks)

Again...not trying to say anything negative....just informative. Folks that come along today (now) won't have any idea what I mean...they'll see the first 3 (or was it 4) action packed most excellent posts.

I know this is coming off as a complaint, but it's really not.

Now......can you do wheelies yet?

;-)

Thanks for all the great words.
 
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Rdrcr

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rdrcr; even though it's doubtful I'd ever install a turbo I really enjoyed your posts, details and humour.

The only thing I found confusing; and maybe you realized this (or not) was you generated a few empty posts as placeholders, so when I checked back every few days or so, the forum software knows where I've last been and takes me to the last post I have not seen. (generally a few posts by others or maybe yourself) and not really the last edited post.

I can understand you wanted all the info in the first few posts....and I'm not complaining...I found it interested, but it may throw a few folks off the scent of the meat an potatoes if they are not aware of how that was all written. (I detected a sniff of that already by one or two folks)

Again...not trying to say anything negative....just informative. Folks that come along today (now) won't have any idea what I mean...they'll see the first 3 (or was it 4) action packed most excellent posts.

I know this is coming off as a complaint, but it's really not.

Now......can you do wheelies yet?

;-)

Thanks for all the great words.
You're welcome!
And, thank you for finding the humor!

In hindsight, I should have waited until I had my entire piece was ready and then post all the content at once. That would have been better and less confusing.

No wheelies. ;)

Mike
 
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Rdrcr

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3978C6FB-8FEC-49BD-B727-CE02871F8C99.jpeg

I was working the tractor for a full 8 hours today. The tractor ran great! The tractor coolant temperature and EGT’s we’re consistent throughout all the digging, grading and transporting of materials. I’m very pleased.

Mike
 
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Rdrcr

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Not surprising, with the fuel turned up, the tractor is consuming more fuel. Noticeably more than when stock. However, it still seems pretty good. It's looking like a gallon per hour of use.

I'll continue to monitor and report back.

Mike
 
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Rdrcr

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The PTO difference is amazing when you can get to doing work with it.

All the other pushing and going up hills and stuff is just loading the hydrostat up to its' relief pressure.

So you might look into that pressure relief if you want to burn rubber or go fast. I haven't monkeyed with my pressures because I love my baby and there's really no where that I would want to go that fast on a tractor of this size :). You can adjust the hydro to make more power to the wheels.
I believe this topic regarding the HST deserves some additional thought and research.

Over the weekend I was attempting to dig out another buried old growth stump and I continually hit the HST pressure relief (M) while trying to loosen the stump in the earth. Which got me thinking, does the L3301/L3302 and L3901/L3902 have higher pressure limits? If so, what are those limits? If not, can they be increased? Would it be safe to increase them?

I think drewzee87t presents an interesting argument.

We know the Turbo really increases the power to the PTO and that's the focal point of the benefits of this modification.
But, on HST equipped tractors, is it possible to increase the overall performance by lifting the limits of the HST relief?

Mike
 
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PoTreeBoy

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I believe this topic regarding the HST deserves some additional thought and research.

Over the weekend I was attempting to dig out another buried old growth stump and I continually hit the HST pressure relief (M) while trying to loosen the stump in the earth. Which got me thinking, does the L3301/L3302 and L3901/L3902 have higher pressure limits? If so, what are those limits? If not, can they be increased? Would it be safe to increase them?

I think drewzee87t presents an interesting argument.

We know the Turbo really increases the power to the PTO and that's the focal point of the benefits of this modification.
But, on HST equipped tractors, is it possible to increase the overall performance by lifting the limits of the HST relief?

Mike
The 2501 has the same hydrostat unit as the 3301/3901 and the same 28:27 input ratio. The 2501 relief pressure is only 100 psi less than the 3301/3901, but yours may be at the lower end of the spec.

I wonder what the HP/torque curves look like.
 
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