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21
General Discussion / Re: heat exchanger
« Last post by BruceM on October 18, 2018, 05:35:08 PM »
No free lunch-  cooling exhaust gas yields precipitation of goop inside pipe, reducing heat transfer and ultimately a horrible cleanup job.  For exhaust heat capture, that issue must somehow be accommodated. 

I'd love to see what Mobile Bob came up with...his work on efficiency of automotive alternators at higher voltages was very impressive. 

22
General Discussion / Re: heat exchanger
« Last post by veggie on October 18, 2018, 05:23:34 PM »

One thing that I was thinking about over the years is a pipe-to-air exchanger on the exhaust.
If you are planning to heat the same room that the engine located, maybe a very long run of exhaust pipe within the room (before exiting the building) would give off a fair bit of heat like a radiator.
The long pipe would work best if fitted with cooling fins. (Called a Fin-Tube)
The idea being that most of the exhaust gas would be cooled drastically before exiting the building by losing it's heat to the finned pipe.

just a thought...

veggie
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Original Lister Cs Engines / Re: Resurrection of a Lister 12/2
« Last post by sirpedrosa on October 18, 2018, 04:04:19 PM »
Hi 38ac

Do you agree with my conclusion?

BR
VP
24
Original Lister Cs Engines / Re: Resurrection of a Lister 12/2
« Last post by 38ac on October 18, 2018, 04:00:47 PM »

Interestingly, if you purchase a new piston there is no notch in it, nor is there any other way of determining the correct orientation. I have measured them and I believe them to be symmetrical so you can fit them either way.

Bob

I also measured them and came to the same conclusion as you.
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Changfa Engines / Re: JD165 - First Run
« Last post by veggie on October 18, 2018, 02:30:42 PM »
When is the load test video coming out?  ;D
Will be interesting to see how it handles loads and what it will pull.

Ahh ! that would be the sequel !  Yes ...
I am currently negotiating with the film crew and editing staff.
I hope to release "Tiny diesel 2" later in the fall.  ;)
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Hi Rob, there is sure to be a formula for working out what the correct gap should be, sadly I don`t know what that is. If you post the diameter of your pistons I am sure that someone like Dieselgman or 38ac will give you that information.

Diameter of pistons: 99.6mm = 3.9212598425"
I've contacted dieselgman.

Thanks
Rob
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I am also a little concerned that you don`t have the same bump clearance on both cylinders, please check out how to set this correctly on the WOK at the top of the home page, courtesy of 38ac.

Hi Bob, but I wrote I had adjusted the bump clearances. They are the same now by putting more gaskets under one cylinder. I did that after I saw that one piston didn't reach as high as the other one. Somewhere further down there must be something that creates a 1 mm difference. This engine has been worked on before I got it. It shows at various spots.
Cheers
Rob
28

I don't see anything " Normal" about the pistons fitting the bores different.  They should all be the same size so why would one be noticeably Different to the Other?

When You pull the engine down I would take the rings off and see how the pistons fit and measure the clearance.  There may be a tolerance difference but not so much that one piston actually Binds.

As for lifting the Cylinders when Fitting the pistons, yes, that is not unusual but if it did it without the rings fitted, I'd be very wary of that.
The difference in piston height in the bores I also think is a concern.  Could be a bunch of things,  Deck heights not right, uneven piston heights, different rod lengths.... Again none of these things good or what you want.

You have a difficulty here in it seems you assembled the engine and the workshop did the machining. I would expect if they did the lot they would have checked things like ring gap and  piston heights and corrected them properly.
You don't need a manual for everything. Many things on engines are roughly the same and close enough is good enough and you know when something is not right.  For an engine that size, any Engine, I certainly wouldn't want a piston tighter than 5 thou and that sounds pretty tight to me.  On the skirt I'd be thinking at least 10 thou or more.  For the ring gap, it varies with which ring generally but something around 10 thou would be common.  It does depend on the ring type as well.

I doubt the oil ring would be causing the problem unless it has no gap because that shouldn't get very hot like the compression rings and expand that much but then again, if it has no gap....  Unfortunately this is all stuff that should have been checked as the engine was re assembled.
The holes in the piston should not be critical. The rings are generaly scrapers so are in fact drain holes.
One thing I always do on engines I assemble is to put a 2mm chamfer on the piston bottom edge. This allows the piston to ride up on the oil film and get between the piston and the bore instead of the lip scraping the oil away and there being no oil film between the 2.  The oil rings are to control the oil film so you do not want the piston skirt taking it all away before hand.

If the thing has been seizing  repeatedly, The bore may now be scuffed or scratched.  I'd be giving it a Close look over and probably running a hone through them  anyway just to make sure there are no high points now. If the ring gaps are too tight, you can almost guarantee they will have dug in and put scratches in the bore.  The gap is where the rings will try to push out the most and have the sharpest corners.  Something I always file a bevel on as well so the ends won't scratch if they are not pinned and can come round the thrust side of the engine.   Depends how deep any scratches are but if they are bad enough, the proper practice would be to go back to the start and hone the bores again and put in oversize pistons and rings.
  Again, depends on what you find and how critical a duty the engine has to do. You can get away with a lot if the engine is more for play but if it's going to do work you need to rely on, at best you will have an engine that probably goes through a bit of oil.

Depending what you find, it may be worth having the engine re assembled by the engine shop so they can check and set all these things.  If they don't do a lot of diesels, I'd be taking it to one that does because they will probably have a good idea off the top of their heads what the numbers should be in the ballpark of.  They don't vary all that much from similar engine to another.
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Original Lister Cs Engines / Re: Resurrection of a Lister 12/2
« Last post by sirpedrosa on October 18, 2018, 01:36:10 PM »
Hi Bob

When I took out the pistons, the gudgeon pin slided better in the direction of the notch. That is on the cyl 1 to the right, and on the cyl 2 to the left (seen from the governor side).

It means - following your clarification - that the notch will be on the side of the exhaust valve, because the 12/2 exaust manifolds are simetric. do you agree with my point if view?

BR
Pedrosa

Ps: open crankcase will be donne when is seats on kart.
30
Hi Rob, there is sure to be a formula for working out what the correct gap should be, sadly I don`t know what that is. If you post the diameter of your pistons I am sure that someone like Dieselgman or 38ac will give you that information.

I am also a little concerned that you don`t have the same bump clearance on both cylinders, please check out how to set this correctly on the WOK at the top of the home page, courtesy of 38ac.

Bob
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