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

Rdrcr

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L2501 w/ S2T Turbo Kit = 35 PTO HP (Current), B2601 (Sold)
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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.
Good to know. Thank you!

I'm hoping that I'll be able to see the HP/TQ curves when the tractor is placed on the PTO dyno.

Mike
 

drewzee87t

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The ability to push would be the effect of modding the relief in the hydrostat. Your wheels would have a lot more power up to the pressure you set. I don't know of anybody that has tested the ability of the hydro or axles and gear on the 2501 or whatever little kubota to get more pressure. I would assume you will find the limit when you break something. I bet you could do wheelies with it and not hurt anything
 
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mdhughes

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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
This seems like a lot of fuel per hour, how did you come up with that number? My L3901DT has averaged 2.2 hours per gallon, this is over 29 tanks of fuel. I try to fill the tank as close as I can each time I fill it and have a meter on my storage tank to get the number of gallons I add to the tractor.
 
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Rdrcr

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This seems like a lot of fuel per hour, how did you come up with that number? My L3901DT has averaged 2.2 hours per gallon, this is over 29 tanks of fuel. I try to fill the tank as close as I can each time I fill it and have a meter on my storage tank to get the number of gallons I add to the tractor.
Rough estimate based on the time I’ve spent on the tractor after filling the tank. I have a couple projects coming up and I’ll continue to monitor the fuel consumption and report back.

I do believe that this particular setup (simple mechanical diesel with Turbo and manually adjusted fuel settings) will consume more fuel than a comparable L3901.
I’m making this assumption on the basis that the L3901 fuel setup is computer controlled and much more precise.

Mike
 
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Rdrcr

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The ability to push would be the effect of modding the relief in the hydrostat. Your wheels would have a lot more power up to the pressure you set. I don't know of anybody that has tested the ability of the hydro or axles and gear on the 2501 or whatever little kubota to get more pressure. I would assume you will find the limit when you break something. I bet you could do wheelies with it and not hurt anything
This would be awesome.

Although, I haven’t heard or read about anyone performing a similar modification. It’s tempting! But, well above my capabilities.

I may just have to be content with the amazing Turbo PTO performance, increased traveling speed in (H) gear and more power for the hills and rear attachments and implements.

Mike
 

ken erickson

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while I have not kept accurate records of operating time/fuel consumption with my HST L2501 I feel like I am burning 1/2 to 3/4 gallon per hour with brush hogging at the high end. I tend to not push the tractor hard and would not be surprised if I did I would be burning closer to 1 gallon per hour.
 
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Oil pan 4

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My tractor burns more fuel but it does a lot more work too. I used to Rev the engine up to 3,000rpm mow through a bunch of tall weeds then it would bog down, roll coal the whole time. Now it maintains speed, the turbo spools up with very little smoke and the rain flapper stands straight up and it mows through tall weeds no problem.
 
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drewzee87t

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It is more efficient and way more powerful. The turbo increases performance when it's needed and scavenges the rest of the time making efficient.

But if you are a non hp tuner gearhead type you should probably just buy your tractor and not mess with it, which is most people. That's fine for you.

If you gave me almost anything i would try to make it work better, whether or not it was really needed.
 
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Rdrcr

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Rdrcr

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CCV/PCV

I ran across some info on another Kubota engine while doing some reading regarding the CCV/PCV and turbocharging. These particular folks were suggesting to remove a steel retainer and spring from the CCV/PCV and then vent to the intake.

1459446A-412A-4615-AAAD-400E764E8FC9.jpeg

9BF271CD-064B-48C6-8794-2CB7DB4E3FE0.jpeg

Now, I’m not sure the D1703 has this assembly (I haven’t checked yet) but, I assume it does.

Assuming that the L2501 has the steel retainer and spring, I would imagine that as crankcase pressure builds, that retainer/spring opens and the gasses are released through the CCV/PCV hose and into the intake manifold (or inlet pipe w/ Turbo). On my Turbo System, I’m re-routing the CCV/PCV gasses to the Turbo inlet pipe. A re-route, which I have done, should be all that’s needed, correct?

Why would these folks suggest removing it? What’s the purpose?

Thinking out loud...
Do they simply want ALL excess crankcase gasses to flow through immediately? Or, do they believe the retainer/spring is an obstruction that is allowing more pressure than they wish?
I don't know.

Mike
 
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Oil pan 4

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I have heard that Kubota PCVs like to fail and blow out crank seals, then you lose all your oil and the engine seizes.
On mine the PCV hose just hangs down a little lower than the engine.
 
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Rdrcr

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I have heard that Kubota PCVs like to fail and blow out crank seals, then you lose all your oil and the engine seizes.
On mine the PCV hose just hangs down a little lower than the engine.
Hmmm, interesting. So, do you believe they are being proactive recommending the removal of the retainer/spring in the event of a circumstance as you describe?

Mike
 

Rdrcr

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For educational purposes, I’m still trying to figure out the CCV/PCV operation on this engine. If anyone has some insight, I’m game.

The tractor and Turbo setup continues to run and perform exceptionally well. I’m trying to log as many hours as I can before the rain comes. I still have a couple jobs I’d like to get done, fingers crossed.

Mike
 

NoJacketRequired

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Perhaps a silly question... In your description of the installation design and the process of installation I'm not sure I read about how you sourced oil to pressure lube the turbo. Did I miss this?

Also... just a casual observation from a different industry. EGT readings are highly subjective. They are subject to large variations based on probe location. In one test we saw a 50 degree difference in EGT reading when we moved the probe from one side of the exhaust pipe to the other - all other variables were the same. Distances between the exhaust valve and probe, angle at which the exhaust impinges on the probe... all these little things produce measurable differences in sensed EGT. I only mention this because you have discussed EGT in terms of absolute values when, in fact, those absolute values can only be meaningful when comparing identical EGT probe locations.

Now you've got me thinking that my little B2410 might need some "help" making more power to deal with heavy snow-blowing loads. Ohhh this is the kind of thinking that gets me in trouble!!!!
 
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Rdrcr

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^^^^^
I’m feeding the Turbo oil from the factory oil pressure switch location using a T fitting. I can take some additional pictures if you like.

While it is true EGT readings can be manipulated (same as dyno results from dynamometers), we’ve positioned the EGT probe with the Turbo, in the same place where we logged our original factory readings. We have maintained the EGT probe location for all testing.

Mike
 
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Rdrcr

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All EGT readings were recorded with the EGT probe installed just after the exhaust manifold outlet.

Here’s the EGT probe placement for stock testing;
CA80DC12-23BC-4439-8E4A-52B35E1719B9.jpeg


Here’s the EGT probe placement for the Turbo system;
9C916944-1587-464F-8628-98E05C43A168.jpeg


Mike
 
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Scott.vy1co

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L2501
Mar 7, 2020
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Amazing write up. Thank you for taking the time to do it--especially the reasoning behind it. The rationale is sound.
 
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drewzee87t

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L45 TLB, B2910 Turbo
May 20, 2016
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Mike,

Please don't do any kind of crankcase to intake feed on a diesel. Yes, it's nice for the environment to burn up your crankcase vapors. No, it's not safe on a mechanical diesel.

If your engine starts to malfunction - e.g. busted or bad leaking rings and gets blowby or fails otherwise (diesel in oil and surely other issues) having a crankcase feed to intake will and has caused runaway dieseling which will grenade your motor and tractor. The pcv thing feeds to a dump tube to atmosphere for a reason.

Thanks!


CCV/PCV

I ran across some info on another Kubota engine while doing some reading regarding the CCV/PCV and turbocharging. These particular folks were suggesting to remove a steel retainer and spring from the CCV/PCV and then vent to the intake.

View attachment 87720
View attachment 87721
Now, I’m not sure the D1703 has this assembly (I haven’t checked yet) but, I assume it does.

Assuming that the L2501 has the steel retainer and spring, I would imagine that as crankcase pressure builds, that retainer/spring opens and the gasses are released through the CCV/PCV hose and into the intake manifold (or inlet pipe w/ Turbo). On my Turbo System, I’m re-routing the CCV/PCV gasses to the Turbo inlet pipe. A re-route, which I have done, should be all that’s needed, correct?

Why would these folks suggest removing it? What’s the purpose?

Thinking out loud...
Do they simply want ALL excess crankcase gasses to flow through immediately? Or, do they believe the retainer/spring is an obstruction that is allowing more pressure than they wish?
I don't know.

Mike
 
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Rdrcr

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L2501 w/ S2T Turbo Kit = 35 PTO HP (Current), B2601 (Sold)
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Mike,

Please don't do any kind of crankcase to intake feed on a diesel. Yes, it's nice for the environment to burn up your crankcase vapors. No, it's not safe on a mechanical diesel.

If your engine starts to malfunction - e.g. busted or bad leaking rings and gets blowby or fails otherwise (diesel in oil and surely other issues) having a crankcase feed to intake will and has caused runaway dieseling which will grenade your motor and tractor. The pcv thing feeds to a dump tube to atmosphere for a reason.

Thanks!
Thank you for the explanation. Makes sense. However, the factory PCV/CCV setup is directing these gasses back into the intake manifold already. How is it any different with the Turbo system?

I just want to verify before making an modifications.

Mike
 
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Oil pan 4

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L185 turbo
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Diesel engines had the crank case vent go to the dirt for ever. I always route it to the ground.
 
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