opinions on engine upgrade? from a 20hp to a 30hp..

[LyHydroponics]

Hi All. I have a 543 with a Kubota 3 cylinder D950. According to the WSM, the D950 has 20Hp at 3000rpm with a maximum torque of 55Nm at 1800rpm. The engine that I am looking to replace it with is a 2 cylinder diesel with 30hp at 2400rpm and a max torque of 107.5Nm at 1680rpm. I would like to know if I could cause any long term damage if i run a motor which has almost double the torque of the original motor? Any help would be greatly appreciated. John

 

[Tazza]

Some say yes, some say no.
The problem that i was told about is the fact that the pumps are made to give X power, with a larger engine they can provide the same power but with the relief valves the oil will go over it when under greater load as the engine will not bog down like the lower powered one. This will create more heat and possible over heating of the pumps. If you just keep that in mind, you shouldn't have a problem. Others have replaced 32hp engines with 46hp ones in 743 machines without any issues.

 

[LyHydroponics]

Some say yes, some say no.
The problem that i was told about is the fact that the pumps are made to give X power, with a larger engine they can provide the same power but with the relief valves the oil will go over it when under greater load as the engine will not bog down like the lower powered one. This will create more heat and possible over heating of the pumps. If you just keep that in mind, you shouldn't have a problem. Others have replaced 32hp engines with 46hp ones in 743 machines without any issues.

Hi Tazza, thats pretty much the info that i was after. Thanks. I figured that with a higher torque engine, i wouldnt have to hold the revs at a higher range. In doing so, i thought that pump flow may not be as high and the hydraulics may be slightly slower moving, but the engine itself shouldnt bog down as much. With the kubota D950, I wasnt able to find oversized liners in time, So i had them honed and I put it all back together. Its running now, but there is definitely a noticeable lack in power with minor blow-by. So Im basically going to run it until the motor gives way, or i get this other motor for it. If there are other opinions on the upgrade, I would still really like to hear them. Thanks John

 

[Tazza]

Hi Tazza, thats pretty much the info that i was after. Thanks. I figured that with a higher torque engine, i wouldnt have to hold the revs at a higher range. In doing so, i thought that pump flow may not be as high and the hydraulics may be slightly slower moving, but the engine itself shouldnt bog down as much. With the kubota D950, I wasnt able to find oversized liners in time, So i had them honed and I put it all back together. Its running now, but there is definitely a noticeable lack in power with minor blow-by. So Im basically going to run it until the motor gives way, or i get this other motor for it. If there are other opinions on the upgrade, I would still really like to hear them. Thanks John

I'm not sure if its the same basic setup as a V1702, but with one less cylinder, but you could probably get it sleeved to bring it back to spec. The V1702 engines run a dry liner, you machine the old one out and press a new one in and machine it to size to bring it back to spec.
Its an option.
Its not a bad idea to do a compression test to see where you are at on wear. Did you measure the bores after honing them? and new pistons and rings?

 

[LyHydroponics]

I'm not sure if its the same basic setup as a V1702, but with one less cylinder, but you could probably get it sleeved to bring it back to spec. The V1702 engines run a dry liner, you machine the old one out and press a new one in and machine it to size to bring it back to spec.
Its an option.
Its not a bad idea to do a compression test to see where you are at on wear. Did you measure the bores after honing them? and new pistons and rings?

hi tazza, yeah i posted about the problem with my d950 about 2 weeks ago. the bottom of the bore itself was warped and had excessive ovality. What we found was that the liners themselves hadnt worn at the bottom, but that the block had warped. We ended up putting it all back together with the original liners, and new rings. The pressing job that we needed it for has been done on the farm, so now its just a matter of getting a new motor for it. While having it apart, i found that there was a problem with the injector pump as well, so in the long run it will be cheaper and easier for me to chuck in a new engine.

 

[Tazza]

hi tazza, yeah i posted about the problem with my d950 about 2 weeks ago. the bottom of the bore itself was warped and had excessive ovality. What we found was that the liners themselves hadnt worn at the bottom, but that the block had warped. We ended up putting it all back together with the original liners, and new rings. The pressing job that we needed it for has been done on the farm, so now its just a matter of getting a new motor for it. While having it apart, i found that there was a problem with the injector pump as well, so in the long run it will be cheaper and easier for me to chuck in a new engine.

The pump alone will set you back a fair bit to get serviced, its not a bad idea to look on ebay and see if any come up.
The warp could be machined out, but the pump will still need to be professionally serviced to get it back to how it should be. At least you are running, if its not an urgent thing, you can keep your eyes peeled for a replacement engine.