Changfa running in Listeroid territory :-)

[veggie]

After some governor adjustments, the Changfa is comfortable at 600 rpm.
( I have had it as low as 500 rpm)
Seems the spring tension adjuster on the stock engines is set for optimal control at speeds above 1200 rpm.
Even with the stock governor spring, better control at lower speeds can be gained by adjusting the threaded spring tension rod to allow a bit of tension (less linkage slack) at the lower speed  position of the throttle knob.

I wonder if a changfa at 600 rpm could drive a 50 amp 12V alternator? (600 watts)  SWEET !!!

http://www.youtube.com/watch?v=qajvVfqqI7o//

veggie

PS: At 600 rpm there is very little knock or mechanical noise. The unit is as quiet as my Listeroid at the same speed.

[mobile_bob]

well ain't that just neater than a skeeters peeter?



now we need to see it pulling a load at 600rpm, and track how the big end brg holds up
at this timing level?

pretty cool

now i gotta try this, see what you have done!

not like i didn't already have a pile of experiments to do already!



bob g

[Henry W]

Veggie,

It sounds pretty good to me.
So all it needed was a lighter governer spring to run at 600.


Good job.

Henry

[veggie]

Veggie,

It sounds pretty good to me.
So all it needed was a lighter governer spring to run at 600.

I think all of these were necessary to make it run stable at 600....
- Lighter gov.spring
- Heavier flywheel
- retarded injector timing by 2 degrees

veggie

[veggie]

As Bob suggested, I would like to set it at 650 and apply a little load.
The speeds are all wrong for me to use the generator head and to solve that I would need a 3" sheave on the gen head.
That does not leave very much belt contact on the small sheave.
I'll see if I can dig up one of those from somewhere.

Alternatively, what I would really like is a Leece bi-directional alternator 
My Delco 12si would spin backwards if I tried to use it in the current mounting configuration.

veggie

[flywheel]

well ain't that just neater than a skeeters peeter?



now we need to see it pulling a load at 600rpm, and track how the big end brg holds up
at this timing level?

pretty cool

now i gotta try this, see what you have done!

not like i didn't already have a pile of experiments to do already!



bob g

(skeeters peeter ?)

[veggie]

I think that's a technical term for:
Highly toposetic incated bi-lateral spacial reverberational algorithmics.  

I bet Skeeter is Bob's dog 

[Henry W]

Veggie,

Yes the heavier flywheel, retarding the timing and lighter governer spring helped getting it to run that slow.
I was surprised that it would run so well at 600 rpm.

Now the thing to do is run it through some tests and see how it holds up.
As Bob wrote, Keep an eye on the bearings.
You might want to retard the timing another 2 degrees and see how it runs.
If it starts and runs fine try another 2 degrees.
If you start having problems then go back.

If you can retard the timing a bit more from what it is now it will take some more stress off the bearings and other parts which should help in longevity. It might also help quiet it down some more.

Again, Good job! And we are looking forward to hear any updates.

Henry

[rcavictim]

WOW!

[V5CVBB]

Any idea what the power and efficiency are like at low rpm? 

Kevin

[veggie]

Any idea what the power and efficiency are like at low rpm? 

Kevin

Hi Kevin,

No idea at this point. Power and fuel consumption charts seem to be non existent for these engines.

veggie

[V5CVBB]

Most of the engines I've seen BSFC curves for show the lowest value just above peak torque. I can't grasp why fuel usage is higher at low rpm when windage and frictional losses are lower. Is it thermal trasfer that is killing efficiency? 

Kevin

[BruceM]

Do Changfa's have the same EPA problems and are not available in the US now?

I'm thrilled with Veggie's low speed Changfa work, that might be a very nice alternative for off grid folks desiring low speed/noise.

[veggie]

BruceM,

To my knowledge the same rules apply as the Roids (May be under the radar at the moment.)
You can also get them on eBay. I think it was the Carol Stream Motor company (eBay store) that has them.

veggie

[rcavictim]

After increasing flywheel mass and retarding the injector timing the problem I still see with really slowing down the Changfa types is in maintaining the functionality of the internal oiling system.

In the case of my JD175A I have an oil pump that sucks oil off the bottom of the sump and the pump pressurizes two passageways.  One feeds oil to the rockers and valves where it returns to the sump through the pushrod galleries.  That will work OK as long as the oil pump can move oil.  The other passageway is designed to fire a solid stream of oil sideways towards the crank throw where for a few degrees per rotation a hole drilled into the side of the throw picks up some oil and through a slant in the drilling angle of this hole in the crank and centrifugal force, it feeds it under pressure into a feed hole cut into the lower rod crank journal to lubricate the lower rod bearing in the usual way. When you remove the con rod the hole in the journal looks like any pressurized automotive crankshaft setup.  When the engine is hot and the oil is thin the oil pressure in the gallery on the output side of the pump drops like a rock from about 6 PSI cold to less than 1 PSI. I have added a pressure gauge and external spin on full flow filter so I know what the pressure is.  That stream being shot at the target hole in the rotating crank may start to droop and miss the target at some low RPM.  If these engines had sleeved bushing bearings on the ends of the crank  the crank could be truly pressurized by a cirumferencial slot around the crank within an end bushing sleeve bearing near the oil pump (timing cover side).  Being that most of these engines use ball bearings on both ends of the crank, it is more difficult by design to pressurize a passageway internal to the crankshaft.  The method used in my JD is rather clever.

In order to increase the lubrication to the camshaft, the wrist pin bushing, and even the main crank ball bearings that all get lubed merely by splash from what is hurled off the rotating crank I added an actual diper to the lower of the two big end con rod bolts.  This mod worked out very well. There is a LOT MORE oil being hurled around now where it can do good.

Perhaps it would be possible to add a restrictor orfice to the hole in the block where the oil jets from towards the crank throw target hole.  This would up the hot oil pressure by a large margin if sized appropriately and produce a real jet of oil under slower RPM conditions.  How the big end bearing of the con rod gets lubed in my Changfa 1115 is still a mystery to me but I suspect it is the same design as most of the modern 195 engines.

I saw a photo of a 195 engine once that appeared to use bushings, not ball bearings on the outer ends of the crankshaft.  In that particular engine I suspect it possible to pressurize the crankshaft the same way it is normally done in a common automobile engine.  I don't think many of our China diesels are made that way.  Ball bearings seem to be much more common.