Tweaking Kubota engines for more power...?

[JohnTso]

In the diesel auto and truck world, it's pretty common to increase HP and overall performance by reprogramming the ECU and/or installing larger injectors. I'm curious if anyone on this site has done this or is looking into doing it.

My B7800 could use a few more HP at the PTO. I would purchase a B26 TBL, but I hesitate at the 19.5 PTO HP rating. I have several 60" PTO powered attachments that I use with my B7800 - rated at 23 PTO HP - that perform OK. A few more ponies passed on to the PTO would be ideal when things get thick, wet or unbroken ground.

Comments/ideas?

John

 

[rbargeron]

Back when I had a L345DT, I was looking to get a little more power. I discovered that the diesel injector pump stop screw had some adjustment range left - it made a noticeable difference in max available power. It was maybe only 10 percent, but it definitely helped get through those spots where it used to bog down. I kept looking at other mods (like an aftermarket turbo) but there are so many tractor sizes available, it was cheaper to just trade up.

 

[SnowRidge]

Most if not all diesel cars and pickups have common rail diesels that have electrically triggered injectors fed by a single high pressure pump on a single line (rail). The ECU controls when they fire, how often they fire, and what the duration is. It also controls rail pressure, so there is a lot that can be tweaked under software (usually to the detriment of engine longevity).

Unless your Kubota has a similar set up, you are probably pretty much out of luck, except possibly for minor adjustments to the injector pump, such as timing and adjustment of the stop(s), as already has been suggested, neither or which I would do if it were my engine.

 

[RobJ]

Then consider the extra load on the engine, tranny, cooling system, etc that the tractor was not designed for. Unless the injection pump is put in a stand and tested, you really have no idea it you are doing very little or way to much by breaking the seals and playing with it.

Buy bigger next time!!

Good Luck,
Rob

 

[rbargeron]

I should have told more of the story - I wasn't flying blind in adjusting my pump. At full fuel the stack didn't smoke at all under load - indicating the stop was set a little lean. I adjusted it until there was a hint of soot (unburned fuel) at full power. The engine put out a little more power and ran fine for many years after the change.

 

[curtisfarmer]

Ya starting jiggering with the factory designed specs. and you are just asking to find out where the other weak links are......pto clutch, tranny, seals,.......Yikes....it could cost more in the end than what it is worth.

 

[Yankee Clipper]

Fellas,

The EPA frowns heavily on anyone tampering with the seals on engines these days not from a reliabilty standpoint but for environmental reasons. The new regs apply to off highway engines now where before the farm lobby had enought clout to get a pass. No longer true.

You can (and will) create other problems that can adversely effect your tractor's longevity and reliability to say nothing about your hip pocket. It also can effect warranty coverage as it states in your owner's manuals.

A word to the wise..

 

[RobJ]

I should have told more of the story - I wasn't flying blind in adjusting my pump. At full fuel the stack didn't smoke at all under load - indicating the stop was set a little lean. I adjusted it until there was a hint of soot (unburned fuel) at full power. The engine put out a little more power and ran fine for many years after the change.

Since this got bumped I'll add the only "field test" to see what you did is to take an exhaust temp reading, about a inch from the port in the head.

 

[rbargeron]

I should probably let it go, but I'll make one more point that counters the predictions of doom and gloom. There's a lot of design margin in low-rpm engines. As an example, tractor manufacturers are apt to offer a model with a normally aspirated engine rated at say 45 hp, and another model with the same basic engine and a turbo, rated 15% higher, and still another with an intercooler etc. rated even higher than that. They are all likely to use the same crank, pistons, transmission, etc. A small up-tick in power will not kill it. It might reduce its average rebuild life from 8,000 hours down to 7,500 - but if it accomplishes the objective its exactly the same economy as buying bigger. Adjustment of the fuel pump rack travel isn't always available - but it's one way to get a small increase in top end power.

 

[medicshawn]

I wish there was a little more info. I would turn my pump up a little bit.