Author Topic: AIr Cooled Chinese L186 Diesel Injector Pump R&R  (Read 594 times)

hwew

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Re: AIr Cooled Chinese L186 Diesel Injector Pump R&R
« Reply #15 on: March 16, 2020, 06:00:21 PM »
I answered in Blue.


to help reduce stress caused by spinning loads that have high inertia.

This makes no sense to me at all.
The whole concept of CS listers is a large, heavy flywheel and slow speed. Some people put extra flywheels on to reduce flicker. If does not matter if it's the flywheel or rotating mass of the load, they have high inertia as do all of the traditional type generators like you want to use.  Never heard of anyone saying they cause " additional stress" ?  Additional to what exactly over any other load??
Any additional weight/mass causes additional stress.

Never heard of anyone complaining about inertia on a generator before. It's the lack of it that gives problems. Your partly right. Itís also dependent how fast an engine is able to respond to a load. Some generators have aluminum flywheels and they do just fine. Some Fairbanks Morse generators with  Wisconsin engines had aluminum flywheels.  That's what gives reactive power and why heavy engines with large flywheels like listers are so well thought of. It is in fact the best thing you can have on a generator.  It's what STOPS them bogging down when heavy loads are dumped on them and voltage sag which the engine then tends to over fuel on when the governor gives it everything to get the revs back up.
And trust me, These engines WILL over fuel when bogged down.  That's what causes stress not rotating mass!

I also strongly question the idea of using 2 head gaskets to reduce compression. Did I say I was going to use two head gaskets? Iím sorry I was not detail enough. I was referring to a head gasket a couple of a thousands thicker if needed to get piston to head clearance correct. Iíve found some engines with not enough clearance. With the Clones itís probably best to check clearance to make sure itís within spec.  That is widely known in engineering/ mechanical circles to be hackery and a very bad practice. No idea why you would want to reduce compression on a diesel? Would only make for harder starting for one thing and have great potential for poorer combustion... particularly if you were thinking of burning veg, Bio or WMO.  They are all harder to light off and the more compression the better.

Also Gaskets are meant for sealing, not adding length to Cylinders. need to add or delete cylinder length by gasket size to get piston to head clearance correct.

If you want to reduce the speed of an engine then you have to derate the power as well. What engine are you intending to run? Your correct, yes you have to derate the engine to operate at a lower speed.
An ST 10 is an over sized generator for a 178 to a 186 so you would want to be more concerned about limiting the load on the head to stop  stressing the engine rather than the rotating mass. Did you read that Iím hoping to get 2400 watts continuous to 3600  watts surge? 
In any case if you are belt driving the head there is an amount of slip and cushioning in the belt so really not sure what you are concerned about?? Read about my concerns in the very beginning of my post. We all know the Chinese clones have a history of failure in one from or another. Is it too much to make sure the engines tolerances are within spec? One thing I try to avoid is guessing.

Weren't you all Gung ho about some Briggs twin a while back on a generator and thought that was the best thing sliced bread? Does this have anything to do about this topic? What brought this up?
Seem to remember you wouldn't permit a less than glowing comment about it. It must of been some negative comment that someone wrote. Some people can be too abrasive and disrespectful when posting comments about a persons topic. Such behavior is frowned upon.
What happened to that thing?? Donít need it. Gave it to my brother to help him start his ST-7.5 generator project. Itís coming along fine.

Hope this helps clear things up.

By the way, I shipped the Briggs out last Friday.
« Last Edit: March 16, 2020, 07:01:10 PM by hwew »

AdeV

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Re: AIr Cooled Chinese L186 Diesel Injector Pump R&R
« Reply #16 on: March 16, 2020, 07:11:35 PM »

to help reduce stress caused by spinning loads that have high inertia.

This makes no sense to me at all.
The whole concept of CS listers is a large, heavy flywheel and slow speed. Some people put extra flywheels on to reduce flicker. If does not matter if it's the flywheel or rotating mass of the load, they have high inertia as do all of the traditional type generators like you want to use.  Never heard of anyone saying they cause " additional stress" ?  Additional to what exactly over any other load??


I think I can see what Henry is getting at - the high inertia will resist the power stroke, which means the rods and bearings are seeing maximum stress - from combustion pressure - for longer, than a lower inertia, free-er revving engine. Which, I suspect, is partially why Listers are built like brick sh*thouses; materials analysis was a new thing back when the CS was designed, if it even existed at all, so better over-built than under...

There is a, possibly apocryphal, story about the development of the RR Merlin engine; during the early tests, they'd run the shit out of an engine until it broke. They'd then beef up the bit that broke, and re-run the tests, until something else broke instead. Then they'd beef up that bit... Rinse and repeat many many times, and you end up with an - almost literally - bulletproof engine, which, as we know, went on to worldwide well deserved fame. I doubt the CS went through much of that; they'd just build it waaaay big enough in the first place.
Cheers!
Ade.
--------------
1x Lister CS Start-o-Matic (complete, runs)
0x Lister JP4 :( - Sold to go in a canal boat.

veggie

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Re: AIr Cooled Chinese L186 Diesel Injector Pump R&R
« Reply #17 on: March 16, 2020, 10:09:11 PM »

I would suggest that the RA Lister company did extensive testing to find the optimal flywheel weight and diameter to balance the line between too much resistance to combustion acceleration vs. having enough inertia to carry good power through the next combustion cycle.
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Johndoh

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Re: AIr Cooled Chinese L186 Diesel Injector Pump R&R
« Reply #18 on: March 17, 2020, 10:14:34 AM »
I have a few of these engines. The Yanmar L48 is a small noisy reliable easy started engine. The 186F engines are very similar to the Yanmar and have been reliable and fairly easily started. They too are very noisy. All are very easy to work at. I'm with Glort on the pump timing, just pack it up or lower it down until it "sounds right". When you buy a car thermostat they are often for many models and come with a selection of gaskets, they can often be adapted as spacers.
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glort

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Re: AIr Cooled Chinese L186 Diesel Injector Pump R&R
« Reply #19 on: March 17, 2020, 12:57:54 PM »
Does this have anything to do about this topic? What brought this up?

What brought it up was just wondering why you were now setting up this little diesel when previously you were so wrapped up ( as you still are) in the Briggs. Just wondering why if the Briggs was so great you weren't still using it?.  But not to worry, just a passing thought not a rhetorical question. 

Would seem to me that the logical thing to do if one were so worried about inertial stress on the engine would be to get a smaller and much lighter  gen head that would still be more that adequate for the intended load. That would to me be the proper way to reduce the stresses rather than try and modify the engine in a way that has good potential to cause other problems, but each to their way of doing things.



« Last Edit: March 17, 2020, 04:50:34 PM by AdeV »

glort

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Re: AIr Cooled Chinese L186 Diesel Injector Pump R&R
« Reply #20 on: March 17, 2020, 01:22:04 PM »

I think I can see what Henry is getting at - the high inertia will resist the power stroke, which means the rods and bearings are seeing maximum stress - from combustion pressure -

I can't, in my mind, visualising it being any different to when the engine was at full load with any other load.
The gen head will have load which is trying to resist the engine.  With a lot of mass or a little, it's trying to slow down.  If it wasn't the load pulling the piston up to compression it would be the flywheel and as the force required will be the same wither way, don't see the difference in which force does it.

What I do see is with a high rotating mass the engine speed is going to be more stable between the firing strokes and therefore the speed changes will be less than if there was a lighter rotating mass used.  The actual load will be the same regardless of the rotating mass attached.

As compression is also the same with  or without a high rotating mass on the engine, the resistance will be the same either way.  The power stroke is going to generate far greater forces than the piston coming up under compression anyway.
i'd be far more worried about getting the timing right so the piston wasn't being slammed into the bore of the engine and the flywheel  ringing like a bell due to being slowed down then sped up again milliseconds later.
The cylinder pressures must be off the charts when that happens.
That's incomparable stress to the piston just coming up to the compression stroke.

As the load is intended to be under the engines power capability, I don't see the worry in stresses there either as the engine was designed to handle more than it's going to encounter in that application so stresses are already reduced.

I got a few thoughts how lowering the compression could create problems on those engines through hands on experience of what I have seen.  Helped a pommie bloke once with his bike he had fitted one of those engines to.  He was riding round the world on Veg oil and was getting a lot of problems which we traced to a new engine he got after the other one got a stone through the crank case.  Worked out the difference comparing it to the engines I had, tried a fix and he no longer had to pull the engine down after every ride.

Anyway...