Kubota diesel conversion from gas engine

[Two Trax]

Hi guys. I have been researching info on converting a TimberKing B-20 from the 25hp Kohler to a diesel. Even asked a few questions here, thanks for the input!

Well I may have located the deal I have been searching for. The motor is a Kubota D1703, 3 cylinder 1.65 litre diesel from a generator with very low hours on it at a killer price. 

Now this is a constant speed govoner engine, 1800 rpm, at which it produces about 25 hp and 60+ lb ft of torque at. It produces 35 hp @ 2800 rpm, torque drops off a bit, BUT it would require changing the govoner around to be able to use it at varying speeds. 

First question, would running it @ 1800 rpm provide enough performance for the mill? Certainly it would require changing the diameter of the engine pulley as the gas motor spins @ 3600 rpm.

Secondly is the weight, this motor weighs about 370 lb and I do not think that figure includes the radiator and fluids. Certainly I will have to build a frame too. Is this too much weight for the B-20?

I am going to look at this tomorrow, about 80 miles away. If it will work, would likely bring it back with me.

Any input that could be provided much appreciated!

[charles mann]

what is the tq difference between the gas burner compared to the diesel? from what i looked up, it seems the gas is half the tq, but almost 10x heavier. tq is key, but having to strengthen your saw beam, then maybe your carriage, may be more trouble than its worth. even if you turned the governor up to turn at 2800 rpm, and being able to, by maybe a change of the high idle solenoid rod, for ea change in rpm, means a change in pulleys each time. and like you said, there is a drop off in tq by increasing the rpm. it may be counter productive to change engines, just for a li bit more tq, even though tq is what you need. but at what sacrifice, added weight, structural add-ons to compensate for the extra wt? im going through this with my build, plenty of tq and hp, but WAY to much weight. but i had already bought the engine, so im going to keep moving forward, just in case i cant sell it for what or more than what i paid for it, and still be able to locate a diesel with the pwr required for the task.  

[doc henderson]

I would contact timberking, they offer diesel options on there mills,  may have answers like rpm and pulley combo as well if the carriage and frame are ok for either,  I have found them to be helpful.  Tell them "doc" told you to call. Hopefully they won't hang up on you. lol,.  ask for matt, he can get you to the best tech. builder.  I see on the website, I can buy a diesel swap motor.  I have the b 2000.

[doc henderson]

it is a 25 hp Kubota engine.  hit the timberking red box link to your left on this site.  if it a close enough engine, they may have instructions for the swap

[Two Trax]

Thanks Doc. Darn if I can find anything on the TK site regarding the diesel. BUT my guess is that the 25 hp diesel option is a smaller displacement higher rpm engine that likely weighs about 100 lb less than the motor I found. 

[doc henderson]

go to TK. choose "other products".  bottom L side of the first page.  shows the engine, you can compare to yours and call in am a see if they can help.

[redbeard]

Ladylake put a Diesel on his B-20 he will be along soon too help out.

[Two Trax]

Found it! I was likely wrong, that engine they list is a 4 cylinder and they reference 80 ft lb torque @2000 rpm. The engine I found does make 80 ft lb intermittent, list 60+ continuous. 

So maybe. Certainly worth a call to TK. 

Good info. Thanks!

[ladylake]

 
 Yes I put a 3 cylinder Isuzu 1.2 liter  29 hp with around 52 # of torque on my B20. Best thing I did, cuts way faster in wide hard cuts than the old Kohler 27 hp gas did  about the same power as my brothers 38 Kohler has, uses less than 1/2 the fuel, I've run 13 hours cutting hard on that 5 1/2 gal tank saving me somewhere around $13000 in fuel in 9000 hours the diesel has on it now.  My Isuzu weighs around 300# with the radiator  , you should be around 400# when done.  I've had no problems except the acme screws wearing out to fast.  I started using bronze acme nuts quite a few years ago which really helped, now the nuts last  4000+ hours and the screws 7000+ hours which is acceptable .  I might try and get that engine turning 2000 rpm but with 60# of torque you should have plenty of power at 1800 rpm plus excellent on fuel use.  I would add at least one, maybe 2 garage door spring on the engine side to help with the extra weight. I have one torsion type on my mill pulling up maybe 100# or so.  Also don't be afraid to slow the band speed done some from the factory speed.  The Kohler ran at 3600 rpm and I'm running a little less than 3000 rpm with the factory pulleys and it cuts better with a slower band speed plus the blade life is better.  Steve

[Two Trax]

Well I spoke with TimberKing this morning. The weight of this engine with radiator and fluids is about 450 lb. They stated it was too heavy for the saw frame and would cause sag in it after a while along with increased wear on the lift mechanisms. 

Thank you Ladylake for your reply. You have a lot of experience withthe B-20 and I respect and appreciate your experience and willingness to share it.

I will keep looking for a smaller lighter diesel. Shame because this was a killer deal.....

[doc henderson]

Just spoke with Matt at TK.  He said the carriage for electric vs gas vs diesel are all designed diff. and the conection to drive wheels are diff.  As you can see the diesel engines are heavy and expensive.  Might consider replacing with a bigger gas engine.

[Two Trax]

The 25 Kohler is working fine right now although with a big oak on the bed she works pretty hard. I just like diesels and have been doing homework for a possible swap while I am in a good position, as in not needing it right now. 

Thanks Doc for your input and calling TK also! A higher hp gas may be an option! I talked with TK this morning on that too. Should present no issue other than possible mounting pattern and length of belt differences. No big deal there. 

[doc henderson]

good luck.  yes you get more with a diesel even if rated less. 8)