Urba Centurion Update - (Kubota diesel, 100+ MPG in mixed driving - Fall 2012 on)

[nemo]

I thought he knew the answer and the delay in posting was just for effect.

[Xist]

Originally Posted by nemo

I thought he knew the answer and the delay in posting was just for effect.

He is playing with our emotions?! What kind of monster is he?!

[changzuki]

Originally Posted by nemo View Post
I thought he knew the answer and the delay in posting was just for effect.

Please select from the on-screen choices:

http://www.youtube.com/watch?v=4bhoWfC1L9k

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~CrazyJerry

[changzuki]

- The D850's fuel injectors...
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The heart of any diesel lies in its fuel system. Get it right and you'll have a very nice performing engine that is very consistent across the board. Get it wrong and you'll be out some time, some money, and likely to be rolling coal.
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The fuel injectors in this unit were previously disassembled, cleaned, fingerprinted , and consequently experimented with. The goal of course was high mpg and given the previous gearing limitation, this fell into place at roughly 48-52 mph. During local mixed driving in that range returned a very respectable 100+ mpg. (The normal range being 127-158).
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Incorporating some of my ideas, and dropping the average to barely over 45mph for over 100 miles of more-or-less continuous driving, yielded a winning performance at the 2014 Green Grand Prix (200+ mpg).
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When changing out the straight 4-speed for the newer overdrive-equipped one, one cannot help but notice the substantially lower rpms that can be obtained at a given speed - and with that, a host of new problems can pile up especially if you've previously dialed in your little Kubota to perform at "X" rpm for "X" speed... All your endless hours and calculations just went out the tailpipe - in a big puff of smoke!
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It was time to revisit the injectors.. (Revisit here means to take apart! )
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In the photo below, the injector at the top is a new Nippendenso replacement.
In the photo below, the injector at the bottom is the stock D850 one.
There are physical differences between these two injectors even though they "cross reference"..
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Differences aside, the bigger question is, will there be a difference in performance?
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And if so, to what degree?
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To get an idea we could simply swap out the injectors and see what happens. I did this and although initially the engine idled marvelously, it just didn't seem to have nearly the get-up-and-go it previously had...
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The mystery vibration seemed to be gone though - so maybe a little investigative work was needed. There was only one way to attack this issue. We would need to go back in time, to the land that time forgot, and revive a "true" classic...
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Ladies and Gentlemen: Meet the "Vintage" Diesel-Kiki Fuel Injector Tester:
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~CrazyJerry

[sendler]

Originally Posted by changzuki

Meet the "Vintage" Diesel-Kiki Fuel Injector Tester:

I have one of those. And the Bosch K gas injector pressure tester.

[changzuki]

- Testing the D850's fuel injectors...
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(Google Images)
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Testing the injectors isn't terribly difficult once it's known what you are supposed to be "looking at" and "looking for".
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Kubota prefers to keep it simple and this is the technical detail:
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So simple is the page from the manual.
Not so simple is trying to capture the spray pattern on a digital camera!
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Having filled an SD Card with worthless shots either before or after the money shot was enough to want to hurl camera and the entire testing assembly across the lawn.
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Then, the injector Gods smiled down upon the testing facility and the magic was captured:
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And on video too (tester/camera/simultaneously/this is not easy to do):
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https://www.youtube.com/watch?v=9MDNees2tio

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http://www.youtube.com/watch?v=rlKhK7L7EwM

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The good news:
After a good cleaning, comparing all three injectors to each other showed them to be consistent in their pressures and patterns with no leakages. Pretty good for 22 year old injectors!
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The bad news:
There's still a problem here and the next target is the 22 year old injector pump.
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More fun on the horizon!!
~CrazyJerry
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[redneck]

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What, no flame test...



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[Hypermiler1995]

Can you imagine the mpg this car could get if basjoos worked it over?

[user removed]

Last time I saw one of those testers was in Marathon Fla in the keys working for Mercedes. We found that if you replaced the springs the pressures and spray patterns were as new. I think they can be shimmed but that memory is 32 years old. The higher the pressure the peak power will drop slightly but the better atomization will improve efficiency. Most of the bad smoking diesels only needed new springs to get the pressure in specs, the smoke was due to poor atomization. We used redline in the tester to get them clean.

regards
mech

[changzuki]

Originally Posted by Old Mechanic

Last time I saw one of those testers was in Marathon Fla in the keys working for Mercedes. We found that if you replaced the springs the pressures and spray patterns were as new. I think they can be shimmed but that memory is 32 years old. The higher the pressure the peak power will drop slightly but the better atomization will improve efficiency. Most of the bad smoking diesels only needed new springs to get the pressure in specs, the smoke was due to poor atomization. We used redline in the tester to get them clean.

regards
mech

Yes Sir - correct on the springs / shims. Below is a previous pic of these injectors disassembled. The items shown as #1 are those shims you've mentioned. In a new Nippendenso replacement injector (top one) they use a shim stack to get the desired thickness. The original painted injector on the bottom used just 1 shim and it was made to the exact desired thickness.
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The new replacement injectors do not jive with the original drawing of the correct injector spray pattern. I thought maybe it was just a fluke - but going through two different places coming up with the correct replacement part number has yielded the same thing. Yes, I now have enough of these old pintle-style injectors to last a lifetime - maybe more!
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~CrazyJerry