Author Topic: JD175 China diesel running at 500 - 1000 RPM  (Read 48378 times)

rcavictim

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Re: JD175 China diesel running at 500 - 1000 RPM
« Reply #90 on: December 13, 2007, 01:20:49 AM »

i am about ready to post some progress on my project as well, changfa powered of course :)


bob g

That`s great Bob.  I look forward to hearing about your results with a 195.

Thanx Jens.
-DIY 1.5L NA VW diesel genset - 9 kW 3-phase. Co-gen, dual  fuel
- 1966, Petter PJ-1, 5 kW air cooled diesel standby lighting plant
-DIY JD175A, minimum fuel research genset.
-Changfa 1115
-6 HP Launtop air cooled diesel
-Want Lister 6/1
-Large DIY VAWT nearing completion

jzeeff

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Re: JD175 China diesel running at 500 - 1000 RPM
« Reply #91 on: December 13, 2007, 01:40:13 AM »

I think you are now in the right min rpm range for a 2600 rpm diesel.

It would be interesting to use a syringe + a killawatt  and check fuel consumption at some different rpms and loads.

As I recall, a 3600 rpm gas engine is best around 2200 rpm.  That's where I run my lawn mower.


ZackaryMac

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Re: JD175 China diesel running at 500 - 1000 RPM
« Reply #92 on: December 13, 2007, 02:52:50 AM »
As I recall, a 3600 rpm gas engine is best around 2200 rpm.  That's where I run my lawn mower.

Just a thought - that engine was designed to work and cool at 3600rpm. If you work it hard at 2200rpm, the fan can't flow enough air over the fins to keep it cooled properly.
Unless of course it's liquid cooled, in which case please ignore the previous statement.  ;D
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Doug

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Re: JD175 China diesel running at 500 - 1000 RPM
« Reply #93 on: December 13, 2007, 03:16:25 AM »
The difference is slight because your not running at the same power level and producing less heat.
The Hotter an air cooled engine gets the better the transfer of heat so they actualy cool more efficiently for less air and the temperature difference is slight.
Air cooled engines are designed to run hot and have quiet a bit of fudged cooling capacity in order for them to run in hot deserts ect ect.
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rcavictim

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Re: JD175 China diesel running at 500 - 1000 RPM
« Reply #94 on: December 13, 2007, 04:22:33 AM »
As I recall, a 3600 rpm gas engine is best around 2200 rpm.  That's where I run my lawn mower.

Just a thought - that engine was designed to work and cool at 3600rpm. If you work it hard at 2200rpm, the fan can't flow enough air over the fins to keep it cooled properly.
Unless of course it's liquid cooled, in which case please ignore the previous statement.  ;D

While that seems to make sense the power output of the engine is reduced at reduced RPM so the heat produced ought to be correspondingly less at the same time as the air turbine makes less cooling airflow.  This may be close enough to being a linear relationship that all will be OK at lower RPM.  Of course if you try to overfuel any engine at any given RPM you are going to overheat it and likely hurt it.

There is a phenomenon which I will call `sonic shock cavitation` which can occur next to the coolant side of a cylinder wall in a liquid cooled diesel engine which prevents heat from being transfered to the coolant despite the flow and level of coolant as measured in and out of the engine block appearing normal.  This can cause localized overheating damage and cylinder wall lubricant breakdown in liquid cooled engines where power levels are pushed to upper limits.  It need not be a concern to slow speed stationary, naturally aspirated engine owners.  There are specially formulated coolants that can hold off the formation of this sonic cavitation.  They are expensive.
-DIY 1.5L NA VW diesel genset - 9 kW 3-phase. Co-gen, dual  fuel
- 1966, Petter PJ-1, 5 kW air cooled diesel standby lighting plant
-DIY JD175A, minimum fuel research genset.
-Changfa 1115
-6 HP Launtop air cooled diesel
-Want Lister 6/1
-Large DIY VAWT nearing completion

rcavictim

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Trouble!
« Reply #95 on: December 13, 2007, 07:49:39 PM »
That test run at 540 watts with the engine running at about 1675 RPM and the big flywheel at about 850 was going so well.  I let the thing continue to run after the 20 hour point in my first extended test run and logged 31 hours.  BTW the fuel consumption got better yet in the final measure.  31 hours, 11 litres of fuel used.  That is 0.355L/hr.  The previous number was 0.364.  This may be fuel measurement technique noise.  Anyhow it confirms that this is a real number.

When I went to check at 31 hours the machine was running just fine but had a bad vibration that was not there before..  It got really bad as I tried to increase the speed higher to where all was fine before.  I shut the system down and removed the belt which then isolated the large flywheel from the system. I wanted to determine if it was the poroblem, or if the problem was in the engine (carbon buildup perhaps?),  The plant was re-started with only the engine belted to the DC head.  The new vibration was gone.  OK, so something is wrong with the large flywheel mechanism.  The big flywheel still rings like a bell when rapped with the knuckles and a visual inspection shows nothing amiss.  It spins like silk seemingly forever on the 40 hour old new bearings, but there is a spot that makes a `critch` sound in the rotation and that spot is always the same point in the circle.  At this point it appears I may have a early bearing failure issue.  It may be sliding motion between the inner of one of the shaft bearings and the shaft.  If that is the case, locktite will fix it.  Trouble is I already did that to the pulley end as that appeared when my bearings were brand new.  I do not understand how that could be the cause of the vibration I saw though and do not believe it is related.

More testing and possible bearing removal + examination will now commence.

This gives me a forced opportunity to test the fuel consumption without the big flywheel and it`s belt drive in the loop.

Film at eleven.
-DIY 1.5L NA VW diesel genset - 9 kW 3-phase. Co-gen, dual  fuel
- 1966, Petter PJ-1, 5 kW air cooled diesel standby lighting plant
-DIY JD175A, minimum fuel research genset.
-Changfa 1115
-6 HP Launtop air cooled diesel
-Want Lister 6/1
-Large DIY VAWT nearing completion

okiezeke

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Re: JD175 China diesel running at 500 - 1000 RPM
« Reply #96 on: December 20, 2007, 10:25:59 AM »
Just discovered your saga of the flywheel and read it from end to end.  Superb work in the finest DIY tradition.  I'm sure eventual outcome will be a usuable machine.  I still wonder sometimes about a rail car wheel.  Keep up the good work!!!

Zeke
Changfa type 25hp with 15kw ST head
Lovson 20-2 in blueprinting/rebuild
International TD-15 B  1962 dozer
Changfa 8 hp., 280 A battery charger

mobile_bob

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Re: JD175 China diesel running at 500 - 1000 RPM
« Reply #97 on: December 20, 2007, 05:30:55 PM »
i have given alot of thought to the rail car wheel as well,,, boy that would make a hell of a flywheel

another on that would be easier to do for me, would be a stub end of a hd truck axle and a set up duals
that has got to be about 750lbs of rotating mass, and balanceing would be a snap! :)

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

okiezeke

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Re: JD175 China diesel running at 500 - 1000 RPM
« Reply #98 on: December 20, 2007, 05:35:43 PM »
Bob,
750 lbs!  Is it possible to have too much of a good thing?

Zeke

ps  I think our listeriod conspiracy may tend to be everywhere from right to left.  More the merrier!
Changfa type 25hp with 15kw ST head
Lovson 20-2 in blueprinting/rebuild
International TD-15 B  1962 dozer
Changfa 8 hp., 280 A battery charger

rcavictim

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Re: JD175 China diesel running at 500 - 1000 RPM
« Reply #99 on: December 20, 2007, 06:39:33 PM »
Just discovered your saga of the flywheel and read it from end to end.  Superb work in the finest DIY tradition.  I'm sure eventual outcome will be a usuable machine.  I still wonder sometimes about a rail car wheel.  Keep up the good work!!!

Zeke

Thanx for the compliments!

The saga has continued while I have been silent here.  I have installed a DIY interface adapter that fits into the cavity in the timing cover on the JD175A that previously held the oil filter `rock screen`.  This has provided two 3/8 inch ports run to an external 10 micron  spin-on hydraulic oil filter.  I struggled with some leaks at first but now have everything under control. In the process though I suspect a particle of broken o-ring or RTV sealant made it`s way into the pressure passage to the rocker arm gallery and partially blocked the spray nozzle thus starving the rocker arms of oil spray.  I destroyed one pressed in steel bushing and compromised the other and did slight wear damage to the hardened rocker shaft in one 9 hour run.. I need to order a new replacement shaft.  I have restored oil flow, machined and installed yellow brass bushings on both rockers and they have survived the latest 40 hour continuous system test with flying colors.

Mobile Bob will be pleased to hear that I abandoned the use of locktite on the rocker set screws and just torqued down the lock nuts with a few hammer taps on the box end wrench.

Here is a picture of the new full flow oil filter system.  Use the scroll bar at the bottom of this post to see the whole image.





I believe that carbon buildup on the piston is a possible cause of the perplexing vibration event that I witnessed.  At the time this was after a 30 hour run with very low fuel throughput (0.3`ish litres per hour) and a rather cool exhaust temp in the neighborhood of just 210 F.  I have since run the engine hard to clear it out, reconnected all the belts and large flywheel and run the plant at higher fuel input (0.55 litres per hour) resulting in an exhaust temp of 300 F for 40 hours continuous at 1700 RPM with absolutely no changes in operating behaviour or distress.

I have also determined that the considerable drag of spinning the AC Kohler head with no electrical connection is nearly identical to asking the DC head to make an additional 500 watts of electricity.  When the plant has everything belted up (both gen heads and large flywheel) and run at just 500 watt DC load to yield low hourly fuel consumption numbers, the inclusion of the unused AC head in the active belt path bumps the hourly fuel consumption up by a factor near 1.6X.  This is terrible.

At the same time I have also determined that the addition of the large flywheel in the active belt path adds an insignificant amount to the fuel consumption.

I am pleased to report that my DC head is indeed capable of acting as a starter motor from the very 48 volt battery bank that it will be connected to as charger!  I can therefore unbelt the AC head and still enjoy electric start.  It turns out that with the large flywheel and DC head belted to the engine I absolutely cannot hand crank start the engine and electric start is absolutely necessary.

In the true tradition of the best DIY, I am making progress!   8)
« Last Edit: December 20, 2007, 06:42:58 PM by rcavictim »
-DIY 1.5L NA VW diesel genset - 9 kW 3-phase. Co-gen, dual  fuel
- 1966, Petter PJ-1, 5 kW air cooled diesel standby lighting plant
-DIY JD175A, minimum fuel research genset.
-Changfa 1115
-6 HP Launtop air cooled diesel
-Want Lister 6/1
-Large DIY VAWT nearing completion