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

Rdrcr

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Thanks Mike, I'll come up with something.

Solo
And, for clarification, when I was originally using standard hose for the Turbo oil feed and drain lines, we were using off-the-shelf brass fittings you can source virtually anywhere. That works too. It just depends on what you prefer to use, standard fittings/hoses or AN fittings/lines.

Mike
 
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Hahnsolo

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I did go with stainless steel fittings and lines and it definitely was more expensive. In retrospect, I probably could have used brass fittings and rubberized hose. Oh, well. It's a learning process.

Solo
 
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Hahnsolo

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OK, took the turbo into a local hardware store today and found out the threaded hole for the oil inlet on the turbo is a 10mm x 1.25 thread. Found a fitting online that has a 4AN thread on the other side. Good to go!

Solo
 
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Rdrcr

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L2501 w/ S2T Turbo Kit = 35 PTO HP (Current), B2601 (Sold)
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OK, took the turbo into a local hardware store today and found out the threaded hole for the oil inlet on the turbo is a 10mm x 1.25 thread. Found a fitting online that has a 4AN thread on the other side. Good to go!

Solo
Correct! Turbo oil feed is 10mm x 1.25 on the turbocharger. 1/8 NPT on the engine block for the oil pressure sender.

Mike
 
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Hahnsolo

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Cool, thanks. Did you use sealant on any of your fittings during assembly? Specifically, the 1/8" NPT fittings? I'm looking at a Permatex High Temp sealant for that.

Solo
 
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Rdrcr

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L2501 w/ S2T Turbo Kit = 35 PTO HP (Current), B2601 (Sold)
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Cool, thanks. Did you use sealant on any of your fittings during assembly? Specifically, the 1/8" NPT fittings? I'm looking at a Permatex High Temp sealant for that.

Solo
Yes. Just a small application of Permatex 59235 on the 1/8 NPT and 10mm x 1.25 fittings.

Mike
 
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Hahnsolo

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So this is really frustrating. I received all of my fittings today to hook up the oil system to the turbo, and come to find out, the 1/8"NPT fitting for the engine block is the wrong size! I guess the oil pressure switch on a 2501 is a different thread size than a B2650. Damn, back to the drawing board.

Solo
 
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number two

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I would have expected the thread to be 1/8PSP instead of 1/8 NPT.
Difference of 27 vs 28 threads per inch-very close?
Good Luck!
 
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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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So this is really frustrating. I received all of my fittings today to hook up the oil system to the turbo, and come to find out, the 1/8"NPT fitting for the engine block is the wrong size! I guess the oil pressure switch on a 2501 is a different thread size than a B2650. Damn, back to the drawing board.

Solo
Did you measure the threads on your oil pressure sender? That’s the best way to go. We have several L2501 Turbo Kit installations and all have used the 1/8 NPT without issue.

Mike
 
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Hahnsolo

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I measured them the best I could. Measuring is not that accurate though. If you look at the picture, you can see the tapered threads on the original oil sender unit are tapered BSPT threads. The fitting on the right is a standard American NPT thread, and you can see visually it is bigger than the BSPT thread. An NPT thread WILL NOT even start threading into a BSPT hole. This is where the frustration comes in. I just got off the phone with a local supplier who actually has a 1/8" BSPT male to 1/8" NPT female adapter. I'm going to pick one up today and hopefully have an assembly post ready this weekend. Stay tuned. . .

Solo


Solo
IMG_9625.jpg
 
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Rdrcr

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^^^^
That indeed appears to be BSPT!!!

I completely understand your frustration....and trust me, I feel it. When I transitioned from the brass fittings to AN fittings, I miscalculated the positioning and orientation of several components around the engine and engine bay leading to needless purchases of AN fittings that simply didn't work. They were costly mistakes. I now have drawer full of fittings, lol.

Mike
 
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Rdrcr

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Mike! Hold the presses! I think I just discovered something that could potentially destroy the turbo in your 2501 and your production kits!

It all started when I was looking for an oil outlet flange to fit the TD025. When I searched for "turbocharger oil outlet flange" I kept getting hits for "turbo oil inlet flange". This kept happening, and I would look at the TD025 and see that there was a threaded hole on the topside of turbo when mounted, and a large hole with two smaller mounting holes on the bottom side, like this:

View attachment 110120

View attachment 110121

It kept bugging me, like a pebble in my shoe: Why is it not called an oil outlet flange? Then, last night in the middle of the night, it hit me: OMG, I've been assuming that small hole on the top of the turbo was the oil inlet. IT'S NOT! THAT IS THE OIL OUTLET SIDE!

The idea is to pump oil into the turbo through the large bolt-on inlet flange on top and fill up the reservoir, while the outlet side with the small fitting drains it. Interestingly, when you look into that small bored outlet hole on the turbo, you see two small channels on the sides and one small hole directly in the center. I believe this may be to allow pressure to build up and flood the bearings (or bushings) in the turbo to keep things properly lubricated. Flipping the configuration around is an unknown situation that could potentially damage the turbocharger down the road. There are two different bearing types commonly used in turbochargers. Here is a good description of the two types and how they differ in operation:


The Mitsubishi TD025 turbocharger used in our small Kubota tractors is of the journal bearing type, requiring sufficient, constant pressure to keep things lubricated, as described in this link to turbo oil supply and drain systems:


Curiously, almost all the oil inlet flanges advertised online have a very small orifice in them as well, which would tend to indicate that they are for ball bearing systems instead of journal bearings. One of these oil inlet flanges could still be used if you drill out the small orifice size to allow more oil flow to the inlet. It would make sense then, that the outlet side of the TD025 turbo DOES have a smaller orifice to facilitate keeping oil pressure up inside the reservoir and the journal bearings.

So why are the inlet and outlet ports flipped 180 degrees when you purchase an off-the-shelf TD025 turbo?

Apparently, a stock TD025, it is designed to HANG from an exhaust manifold instead of PERCH on top of the manifold because it was designed for a different application in small cars. This is obviously just backwards to what is needed in our Kubota's. So, how are you supposed to reposition the oil inlet and outlets?

This is achieved through a relatively common process called "clocking", and what it refers to (in a nutshell) is the relative axial position of the exhaust side of the turbocharger to the axial position of the compressor side. In other words, the exhaust side needs to be rotated in such a way as to align the oil inlet/outlet ports within +/-15 degrees of vertical, with the OIL INLET FLANGE ON TOP, and the compressor side rotated to optimize the tubing path from the turbo to the engine. Here is a video, albeit a little wonky, of how to clock a similar TD04 turbo:


Mike, you may want to research this yourself and give me your input. Is there something I overlooked or misunderstood? Let me know what you think. Thanks.

Solo
Yes, you are mistaken.

Every inch of our L2501 Turbo system has been thoroughly researched and engineered to the fullest. I'm very familiar with Turbocharger 'clocking' and it isn't required for this application. The Turbocharger oil inlet is the threaded portion of the Turbocharger cartridge and the smooth bore hole (with two screw holes) is the oil outlet. There are absolutely ZERO issues with the L2501 Turbo positioning and the oiling system on our Turbo Kit.

As an example, here is an illustration of the Turbocharger positioning on a 100% factory OEM Kubota;
Turbo Positioning.jpg

You can clearly identify that our Turbo system shares the same exact same Turbocharger and Turbo positioning as the factory Kubota setup. Our Turbocharger oiling system orientation is exactly the same as the factory Kubota OEM setup, however, instead of using a banjo bolt and hard lines, we are using AN fittings and lines.

I would suggest that you check with your Turbocharger supplier and Kubota technical assistance with regards to the positioning and oiling requirements for the Mitsubishi MHI TD025 Turbo.

Mike
 
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Hahnsolo

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Hi Mike:

Thanks for the clarification. Apparently, I fell into a very deep rabbit hole. I think I see now where my logic was flawed. My apologies for the confusion. You definitely have better resources and knowledge in this area than I. Your patience and guidance is still greatly 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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Hi Mike:

Thanks for the clarification. Apparently, I fell into a very deep rabbit hole. I think I see now where my logic was flawed. My apologies for the confusion. You definitely have better resources and knowledge in this area than I. Your patience and guidance is still greatly appreciated!

Solo
You're very welcome. It becomes easy to get confused once you begin looking at alternative Turbochargers and/or alternative brand Turbochargers and applications. They're not all the same.

I can point out several other very obvious identifying features on the MHI TD025 (including the Kubota service manual) to make additional points but, it's not necessary. You get it.

Stay off the YouTube and online searches 😂

Mike
 

Hahnsolo

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Yup, lol. Quick question: do I need a restrictor fitting for the oil inlet, or just a standard?
Solo
 
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Rdrcr

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L2501 w/ S2T Turbo Kit = 35 PTO HP (Current), B2601 (Sold)
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Yup, lol. Quick question: do I need a restrictor fitting for the oil inlet, or just a standard?
Solo
A standard AN fitting should be fine. However, once you get the tractor started, check and make sure you have a steady stream of oil from the turbocharger when the tractor is running.

Mike
 

Hahnsolo

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Hey Mike, quick question:

Did you say you machined custom fittings for the engine block oil drain or are they off the shelf?

Solo
 
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