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

Rdrcr

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^^^^
Definitely a AN fitting connection issue. I have a new AN fitting on the way and look forward to having a leak-free L2501 Turbocharger experience!

In addition, we updated the Turbo Charge Pipe so that the OEM factory hood prop rod absorber can function as intended;
Intake1.jpg


Intake2.jpg


Intake3.jpg


Mike
 
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Hahnsolo

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B2650 Tractor, B2782B Snow Blower
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Hi Mike:

Things are looking really good. Quick question: What is the part number for the muffler flange that attaches the turbocharger to the exhaust manifold? I am having a hard time finding it. Thanks.

Solo
 
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Rdrcr

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Hi Mike:

Things are looking really good. Quick question: What is the part number for the muffler flange that attaches the turbocharger to the exhaust manifold? I am having a hard time finding it. Thanks.

Solo
Thank you!
Much progress is being made.

We designed and fabricated the Turbo-to-exhaust manifold adapter. It’s a custom part and isn’t available through Kubota. I can get you one but, I don’t know if it’ll work for your application.

Mike
 

Hahnsolo

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Thank you!
Much progress is being made.

We designed and fabricated the Turbo-to-exhaust manifold adapter. It’s a custom part and isn’t available through Kubota. I can get you one but, I don’t know if it’ll work for your application.

Mike
Ok, that's what I thought after going back and looking at some of the earlier pictures. So, are you using the waste gate on the turbo at all? The TD025 turbo has a max rotational speed of 240,000 RPM, so I would think that running at only 2100 RPM you wouldn't need it. Do you have any idea what speed the turbo is spinning?

Solo
 
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Rdrcr

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L2501 w/ S2T Turbo Kit = 35 PTO HP (Current), B2601 (Sold)
May 7, 2021
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Ok, that's what I thought after going back and looking at some of the earlier pictures. So, are you using the waste gate on the turbo at all? The TD025 turbo has a max rotational speed of 240,000 RPM, so I would think that running at only 2100 RPM you wouldn't need it. Do you have any idea what speed the turbo is spinning?

Solo
Yes, we are using the internal Turbo Actuator Pressure Wastegate that is present on the MHI Turbocharger (I can supply you with the Kubota part number for the Turbo if you like). I'd have to look up the specs on the Turbo again to verify the operating RPM (the Turbo is capable of producing 90HP). But, as far as the actuator wastegate goes, we are using manual adjustments to the actuator to adjust boost pressure.

Having the ability to adjust/increase the boost pressure helps maintain a set HP goal while maintaining/decrease EGT temperature creep.

Mike
 

Hahnsolo

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B2650 Tractor, B2782B Snow Blower
Mar 13, 2023
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Yes, we are using the internal Turbo Actuator Pressure Wastegate that is present on the MHI Turbocharger (I can supply you with the Kubota part number for the Turbo if you like). I'd have to look up the specs on the Turbo again to verify the operating RPM (the Turbo is capable of producing 90HP). But, as far as the actuator wastegate goes, we are using manual adjustments to the actuator to adjust boost pressure.

Having the ability to adjust/increase the boost pressure helps maintain a set HP goal while maintaining/decrease EGT temperature creep.

Mike
Got it. So, the stock Kubota muffler flange that connects the turbo exhaust to the main exhaust pipe is pretty much a unicorn as far as I can tell from my research. I would really be interested in seeing what/how you milled a custom flange. Comparing it to the Kubota drawing, it has to be cut fairly deep to accommodate the waste gate when it dumps excess exhaust. Do you have any drawing or dimensions?

Thanks for your patience - it is really appreciated.

Solo
 
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Rdrcr

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L2501 w/ S2T Turbo Kit = 35 PTO HP (Current), B2601 (Sold)
May 7, 2021
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Got it. So, the stock Kubota muffler flange that connects the turbo exhaust to the main exhaust pipe is pretty much a unicorn as far as I can tell from my research. I would really be interested in seeing what/how you milled a custom flange. Comparing it to the Kubota drawing, it has to be cut fairly deep to accommodate the waste gate when it dumps excess exhaust. Do you have any drawing or dimensions?

Thanks for your patience - it is really appreciated.

Solo
The OEM turbo outlet to muffler flange 'should' be available through Kubota for some applications that use the TD025 Turbocharger. However, will it work for your application? Hard to say.

We had to fabricate custom components to make the Turbo work for the L2501. Unfortunately, I don't have any drawings since all the piping and flanges were done by hand. Are you just looking for dimensions of the flanges? I can get you the OEM Kubota gaskets we used for the Turbo system. The gaskets would give you the dimensions of the flanges and I can provide the flange thickness.

Mike
 

Hahnsolo

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B2650 Tractor, B2782B Snow Blower
Mar 13, 2023
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The OEM turbo outlet to muffler flange 'should' be available through Kubota for some applications that use the TD025 Turbocharger. However, will it work for your application? Hard to say.

We had to fabricate custom components to make the Turbo work for the L2501. Unfortunately, I don't have any drawings since all the piping and flanges were done by hand. Are you just looking for dimensions of the flanges? I can get you the OEM Kubota gaskets we used for the Turbo system. The gaskets would give you the dimensions of the flanges and I can provide the flange thickness.

Mike
Looking at the Kubota part, there is a very sharp upward turn that is most likely due to space constraints. I think I can find the gaskets, but if you can provide the thickness of your flange that would be an enormous help. I do have access to fabrication and assembly facilities.

Solo
 
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Rdrcr

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L2501 w/ S2T Turbo Kit = 35 PTO HP (Current), B2601 (Sold)
May 7, 2021
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Looking at the Kubota part, there is a very sharp upward turn that is most likely due to space constraints. I think I can find the gaskets, but if you can provide the thickness of your flange that would be an enormous help. I do have access to fabrication and assembly facilities.

Solo
We are using the following;

Kubota MHI TD025 Turbocharger - #1A024-17016
Kubota Turbo to Adapter Flange Gasket - #16292-17100
Kubota Turbo to Exhaust Flange Gasket - #16292-17110
Kubota Exhaust Manifold to Muffler Gasket - #T0070-16420

It's a bit overkill but we are using 1/2" thickness for all Turbo flanges. Assuming you are using the TD025 Turbocharger (the best option), you can use the Kubota gaskets for your dimensions and templates.

Mike
 

country_hick

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Mar 2, 2023
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I talked to a Kubota salesman who has been a mechanic. He said the bottom end of the 25hp engine is bulletproof. the top end, not so much. The engine can be hopped up to 28hp with no issues. What he says happens is the excessive pressures and heat crack the head or blow out the head gasket. The good news is if you crack a head a new ready to go chinesium head can be bought for under $500 on eBay.

I know 12 valve Cummins motors that get cranked up often end up with cracked heads.
Take the above information for what it is worth.
 

Rdrcr

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L2501 w/ S2T Turbo Kit = 35 PTO HP (Current), B2601 (Sold)
May 7, 2021
638
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I talked to a Kubota salesman who has been a mechanic. He said the bottom end of the 25hp engine is bulletproof. the top end, not so much. The engine can be hopped up to 28hp with no issues. What he says happens is the excessive pressures and heat crack the head or blow out the head gasket. The good news is if you crack a head a new ready to go chinesium head can be bought for under $500 on eBay.

I know 12 valve Cummins motors that get cranked up often end up with cracked heads.
Take the above information for what it is worth.
I’ve never heard or seen a Kubota D1703 with top end issues caused by any performance enhancing modifications.

Did he specify which 25HP Kubota engine? There are quite a few in Kubota’s lineup over the years. Was he referring to the L2501 and the D1703 specifically? Does he have any experience with modified D1703 engines? Turbocharging? Or, was he simply talking out of his a$$?

Mike
 

Rdrcr

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Wow! This is Excellent! Thanks Mike, this is exactly what I was looking for. . .

Solo
I thought you’d appreciate that! ;)

Mike
 

country_hick

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Mar 2, 2023
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I’ve never heard or seen a Kubota D1703 with top end issues caused by any performance enhancing modifications.

Did he specify which 25HP Kubota engine? There are quite a few in Kubota’s lineup over the years. Was he referring to the L2501 and the D1703 specifically? Does he have any experience with modified D1703 engines? Turbocharging? Or, was he simply talking out of his a$$?

Mike
He was specifically talking about the L2501.

He said his dealership had turned up engines in the past.

I just put it out there to consider.
 

Rdrcr

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L2501 w/ S2T Turbo Kit = 35 PTO HP (Current), B2601 (Sold)
May 7, 2021
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He was specifically talking about the L2501.

He said his dealership had turned up engines in the past.

I just put it out there to consider.
You haven’t provided any details regarding the modifications to consider. What are we considering?
How were these tractors modified?

There are now several Turbocharged L2501’s running without issue for hundreds of hours.
There are even more L2501’s with injection timing modifications running without issues.

I’m trying to understand the purpose of your post?

I have read about ONE turbocharged Kubota tractor that had an engine issue after turbo installation. He melted his pistons after 400-500 hours of hard use. Ironically, he fixed his engine and reinstalled the crude backyard turbo setup.

I inquired about his specific setup several times trying to understand what led to his engine issue.
He was extremely reluctant to admit that he had ZERO knowledge of his combustion temperatures and didn’t have a pyrometer or EGT gauge installed on his tractor. He had no clue what temperatures he was running?!?

That’s plain negligence! You’re asking for trouble without knowing this critical engine health information! And, I’m surprised his engine lasted as long as it did.
You have to monitor EGT temperatures if you’re modifying your tractor! Period!

Mike
 
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Hahnsolo

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B2650 Tractor, B2782B Snow Blower
Mar 13, 2023
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You haven’t provided any details regarding the modifications to consider. What are we considering?
How were these tractors modified?

There are now several Turbocharged L2501’s running without issue for hundreds of hours.
There are even more L2501’s with injection timing modifications running without issues.

I’m trying to understand the purpose of your post?

I have read about ONE turbocharged Kubota tractor that had an engine issue after turbo installation. He melted his pistons after 400-500 hours of hard use. Ironically, he fixed his engine and reinstalled the crude backyard turbo setup.

I inquired about his specific setup several times trying to understand what led to his engine issue.
He was extremely reluctant to admit that he had ZERO knowledge of his combustion temperatures and didn’t have a pyrometer or EGT gauge installed on his tractor. He had no clue what temperatures he was running?!?

That’s plain negligence! You’re asking for trouble without knowing this critical engine health information! And, I’m surprised his engine lasted as long as it did.
You have to monitor EGT temperatures if you’re modifying your tractor! Period!

Mike
Absolutely! The one thing I have found during my own preliminary research is how critical EGT monitoring is. I was shocked to see how fast and how high exhaust temperatures went up when the engine was loaded hard and started rolling coal. Black smoke = higher EGT's, plain and simple.

On another note, I am looking at ordering my turbo and parts in the next little while. I was wondering, do you know how fast (RPM) your turbo is spinning at maximum output on your tractor?

Solo
 
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Rdrcr

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L2501 w/ S2T Turbo Kit = 35 PTO HP (Current), B2601 (Sold)
May 7, 2021
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^^^^
The MHI TD025 has a maximum RPM of 240,000 but, I'm not sure the speed we're spinning simply because we're operating the engine at only 2,105 RPM / 2,400 RPM maximum. I'll talk with our Turbo expert and see if I can figure it out.

Another thing to keep in mind regarding EGT's and load is that all loads are not created equally. So, for example, operating a rear finish mower at maximum RPM on flat terrain and short grass will produce lower EGTS when compared to operating that same finish mower on flat terrain and tall grass. The tall grass will create a higher load thus producing higher EGT's. Operating that same finish mower on hills and tall grass will further increase EGT's. Hence, that is why it is critically important to constantly monitor your EGT's when you are running a Turbo and/or even modified with an injection pump timing mod.

Mike
 

Rdrcr

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L2501 w/ S2T Turbo Kit = 35 PTO HP (Current), B2601 (Sold)
May 7, 2021
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We redesigned the Turbo Intake Charge pipe so the factory Hood Prop Rod Absorber can function as intended;

Turbo1.jpg


Turbo2.jpg


Turbo3.jpg


This redesign was a necessity! Opening the hood was extremely awkward without the assist of the absorber and holding it up with a broomstick was utterly ridiculous.
Now, all is well! :)

We also added an extension to the Exhaust pipe exit to further send exhaust fumes away from the operator station.
I'll share some pictures of that modification soon.

Mike
 
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Hahnsolo

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Equipment
B2650 Tractor, B2782B Snow Blower
Mar 13, 2023
108
182
43
Rocky Mountains
We redesigned the Turbo Intake Charge pipe so the factory Hood Prop Rod Absorber can function as intended;

View attachment 101009

View attachment 101010

View attachment 101011

This redesign was a necessity! Opening the hood was extremely awkward without the assist of the absorber and holding it up with a broomstick was utterly ridiculous.
Now, all is well! :)

We also added an extension to the Exhaust pipe exit to further send exhaust fumes away from the operator station.
I'll share some pictures of that modification soon.

Mike
So, looking at your intake/exhaust pipe routing, I am kind of shocked at the huge size of the main piping, versus the pipe size connecting to the turbo. It looks like 3" diameter? Is there much gain in performance with the bigger pipe, considering the necked-down size into/out of the turbo? Puzzled.

Solo
 
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