L2501 Modifications

Rdrcr

Active member

Equipment
L2501, B2601
May 7, 2021
251
169
43
WA
And…look at what arrived yesterday…
4C5B11E6-650B-4010-87ED-F1C6779DE3DC.jpeg

…a brand new Mitsubishi MHI Turbo!!!!

Mike
 
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Mikemoto17

Member

Equipment
L2501 HST BH77 backhoe LA525 loader woodland Mills Pto chipper
Oct 21, 2020
13
63
13
California
Hey guys I’m back it’s been a minute! The time has come to release a full turbo kit. This will be available to purchase on our website 4Nmotorsport.com in the next two weeks.

I have now pushed this tractor over 350hours with the turbo and it’s Making an estimated 40-45hp with no issues. I will have two options for the kit. You will be able to purchase with a full 304l stainless tig welded exhaust either straight pipe or I can include a 2.5 muffler with a turn down. I will have some pics up here shortly of the full kit.

My apologies for being absent on this forum. I almost lost everything to the Caldor fire out here in California last year. it definitely wasn’t fun and slowed me down quite a bit but I am back at it making turbo kits👍🤘
 

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rc51stierhoff

Well-known member

Equipment
B2650, MX6000
Sep 13, 2021
549
382
63
Ohio
Hey Guys new to this forum. I own a performance shop and I build turbo kits. I started in the diesel world with a 4bt swapped 47 Chevy currently making 600whp 950 tq on 70 psi. I also build custom turbo kits for bmw platforms. I purchased 5 acres of property and jumped on buying an l2501 HST. Reason being is I knew this engine was de tuned from all my research and not having a dpf was a big plus. I am also a huge fan of mechanically controlled Diesel engines. I started off doing a basic rpm increase to 2600rpms. It helped with running my PTO chipper but I eventually found out I needed more fuel. I made a very slight fuel adjustment and it did increase the power. Only issue was of course slightly more smoke. After reading about the D1703 I figured out Kubota retarded the timing to 5 degrees btdc for emissions and to help it get under 25hp and also the air box they are using is a major restriction. The 1703 can run up to 14 degrees btdc. I bumped the timing up to 9 btdc and installed a higher flowing air box and all I can say is wow this thing pulls up my driveway which is a 15% grade like no problem in mid range gear at 2300rpms. Before it would bog down below 1800. I am guessing it’s in the mid 30hp range. Just wanted to share this info. And I will be also installing an oem rhf3 Kubota turbocharger. I’ll be running low boost probably around 5-7 psi. Since I am at 3,000 feet elevation it will help a ton. I’ll post pictures and progress hoping for a solid 40hp out of this tractor 😎😂
Hey there Mr Moto…there is a thread under ‘tractor operation’ about cool downs….lots of topic in there regarding diesel / turbos maybe you could help us out?
 

tractorX

Member

Equipment
KUBOTA L2501 DT 5' BOX BLADE 42" FORKS PIRANHA TB 5' BUSH HOG 6' GRADER
Sep 27, 2013
60
52
18
Rock Spring GA.
whats up gearheads! looks like im up next for the D1703 injection timing and fuel adjustment mod. ran the tractor hard for bout a hour and collected some data for the "before and after." took the FEL and hood off, then took a toothbrush and some dawn to the the engine... spic and span!
also downloaded the l2501 WSM here https://www.pdfmanual4trucks.com/kubota/
got rain tomorrow, so hopeful i can start next couple of days. ill keep yall posted on the progress.
thanks again for all the help and hard work guys 👊
 
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tractorX

Member

Equipment
KUBOTA L2501 DT 5' BOX BLADE 42" FORKS PIRANHA TB 5' BUSH HOG 6' GRADER
Sep 27, 2013
60
52
18
Rock Spring GA.
rain held off... gotta lot done today . took about 4 hours start to finish.
my D1703 had a 0.25mm (1 hole) and a 0.20 mm (2 hole) shim.... i removed the 0.25 shim.

saved some time not having to remove the 3rd injection pipe. i was able to fish it through the manifold. also i did not have to remove the injection pipe over the injectors, i was able to use a 17mm line wrench and a open end wrench to loosen the nuts on top.

all i got for today.... oh, almost forgot! the guard over the fuel limiting screw took about 10 min to cut through with a dremel tool. i plan on starting with a 1/4 turn out. ill hit yall up tomorrow with more progress!
IMG_1169.JPG
 
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tractorX

Member

Equipment
KUBOTA L2501 DT 5' BOX BLADE 42" FORKS PIRANHA TB 5' BUSH HOG 6' GRADER
Sep 27, 2013
60
52
18
Rock Spring GA.
good news
1645320470719.png

had several errands to run yesterday, but was able to fire the tractor up.
picked back up working on the tractor this morning, mainly double checking my work. final step was setting the fuel screw... i just came out 1/4 turn for now. ill dial it in after i install a EGT probe and report back with more accurate data when complete.

now the good stuff! worked it hard for bout 1 hour bush hogging thicket and privet hedge. started out at 1900rpm and noticed a slight drop in rpm's, so throttled up to 2100rpm's and never looked back. before the mod i would usual have to lift and lower a couple of times to clear 1/2' - 1 1/2" privet. more pto HP was my target. i have no idea how much HP was gained... but this is not the same tractor!
 
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tractorX

Member

Equipment
KUBOTA L2501 DT 5' BOX BLADE 42" FORKS PIRANHA TB 5' BUSH HOG 6' GRADER
Sep 27, 2013
60
52
18
Rock Spring GA.
EGT probe arrived today. gonna try to get it installed by this weekend. ill report back with the final tweaks and some seat time data if weather cooperates 🙏
 
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Rdrcr

Active member

Equipment
L2501, B2601
May 7, 2021
251
169
43
WA
^^^^
I’m looking forward to hearing about your EGT recordings and compare them with mine and NetMagi.

Mike
 

Rdrcr

Active member

Equipment
L2501, B2601
May 7, 2021
251
169
43
WA
^^^^
Getting closer, just waiting for some parts to arrive.

Mike
 
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Rdrcr

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Equipment
L2501, B2601
May 7, 2021
251
169
43
WA
^^^^^
Excellent! Can’t wait to hear the results!

Mike
 
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tractorX

Member

Equipment
KUBOTA L2501 DT 5' BOX BLADE 42" FORKS PIRANHA TB 5' BUSH HOG 6' GRADER
Sep 27, 2013
60
52
18
Rock Spring GA.
here's what i got for today,
tractor: L2501DT
elevation: ~1200ft
weather: @ testing 71*
tractor running time: 1:15min
implements: FEL & 5' bush hog
total operating weight: ~4200#
max rpm: 2350 vs NetMagi's 2650
terrain: very hilly

operating tractor,
dirt: WOT L2-L4 gear (4X4 engaged) FEL work, temps 450*-600*

N road: WOT H8 gear (4X4 disengaged) 1mi ~10 deg hill, temps reached 936*

S road: WOT H8 gear (4X4 disengaged) 2.8mi. drove down to corner gas station for fuel.. pretty much a down hill ride. 1st mile on the way back temps gradually increased to 650* . from there, turned off main road and headed up to the ridge. its about 1/4mi up to the top at ~20 deg angle. temps peaked at 1070* and rpm's dropped 1800-1700.

still see a puff of black smoke when starting the tractor... not as bad as before the mod though. i did NOT notice any smoke under loads.
still have plenty of dirt work, clearing, and bush hogging to do this year... im ready for some warm weather and hard work with this little bull!

questions, comments or something i can improve on?

thanks for all yalls help @NetMagi and @Rdrcr
 
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Rdrcr

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Equipment
L2501, B2601
May 7, 2021
251
169
43
WA
^^^^
You’re EGT’s appear to be inline with both mine and NetMagi’s findings. Very good!

To confirm, you’ve advanced the injection timing and increased the fuel a 1/4 turn, and left the RPM limit stock, correct?

Mike
 

tractorX

Member

Equipment
KUBOTA L2501 DT 5' BOX BLADE 42" FORKS PIRANHA TB 5' BUSH HOG 6' GRADER
Sep 27, 2013
60
52
18
Rock Spring GA.
^^^^
You’re EGT’s appear to be inline with both mine and NetMagi’s findings. Very good!

To confirm, you’ve advanced the injection timing and increased the fuel a 1/4 turn, and left the RPM limit stock, correct?

Mike
all correct,

my bro n law and i decide to leave the throttle limit stock. the D1703 M DI E2B model is 36.7 HP @ 2800 rpm with max torque @ ~1700 rpm.
the D1703 in the stock l2501 is 24.8 HP @ 2200 rpm and max torque @ ~1500 rpm.
what are the benefits of adding x300 rpms.... just speed and HP right?
1 more question.... do you think the temps recorded (1070*) going up the ridge are good or should i try to push that # up to the ~1200* tweaking the fuel?

i work the tractor hardest moving dirt.... BB on back with rippers set aggressive and bucket in float scooping up dirt at the same time. this is the temps/data i need.
prolly gonna be summer before i can do heavy dirt work... its gonna be a wet spring says the farmers almanac.
 

Rdrcr

Active member

Equipment
L2501, B2601
May 7, 2021
251
169
43
WA
all correct,

my bro n law and i decide to leave the throttle limit stock. the D1703 M DI E2B model is 36.7 HP @ 2800 rpm with max torque @ ~1700 rpm.
the D1703 in the stock l2501 is 24.8 HP @ 2200 rpm and max torque @ ~1500 rpm.
what are the benefits of adding x300 rpms.... just speed and HP right?
1 more question.... do you think the temps recorded (1070*) going up the ridge are good or should i try to push that # up to the ~1200* tweaking the fuel?

i work the tractor hardest moving dirt.... BB on back with rippers set aggressive and bucket in float scooping up dirt at the same time. this is the temps/data i need.
prolly gonna be summer before i can do heavy dirt work... its gonna be a wet spring says the farmers almanac.
I believe most guys willing to perform this modification are going to want to keep the stock RPM limit.

I personally wouldn't mess with anything or add more fuel until you've had a chance to operate the tractor a bit longer. I think your EGT's are right where you want them. Adding more fuel will increase the EGT's. If you're getting the desired performance now, there's no need.

Mike
 

tractorX

Member

Equipment
KUBOTA L2501 DT 5' BOX BLADE 42" FORKS PIRANHA TB 5' BUSH HOG 6' GRADER
Sep 27, 2013
60
52
18
Rock Spring GA.
I believe most guys willing to perform this modification are going to want to keep the stock RPM limit.

I personally wouldn't mess with anything or add more fuel until you've had a chance to operate the tractor a bit longer. I think your EGT's are right where you want them. Adding more fuel will increase the EGT's. If you're getting the desired performance now, there's no need.

Mike
thanks mike!

really enjoy working on the diesel... i've learned (and still learning) a lot from yall!
can't wait to hear the results from your turbo mod 👊
 
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