Author Topic: 20 cc Horizontal 2 Stroke Diesel  (Read 49104 times)

Offline gbritnell

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #285 on: April 14, 2019, 12:55:28 PM »
Roger,
Although I haven't commented much on your build threads I am totally impressed with the experimentation and work you have been doing on both the injector and engine. I wonder if it would help to make larger flywheels to try and get the rpm's down? Even with gasoline engines flywheel diameter makes a big difference in low speed performance.
I know a diesel requires greater compression so it takes more inertia to get it past the compression stroke.
The model diesels on YouTube are capable of quite slow running and have what seems to be extremely large flywheels compared to the cylinder size.
I'm still following and learning a lot from your work.
gbritnell
Talent unshared is talent wasted.

Offline 90LX_Notch

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #286 on: April 15, 2019, 12:12:08 AM »
Roger,

I'm still following along.  It's nice to see you back at it.

-Bob
Proud Member of MEM

My Engine Videos on YouTube-
http://www.youtube.com/user/Notch90usa/videos

Offline Art K

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #287 on: April 15, 2019, 03:27:56 AM »
Roger,
Good to see you back at it. George is right you have done an amazing amount of experimentation on this engine. I agree with him on the flywheel thought. Most old engines you see have massive flywheels. Just a thought.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #288 on: April 15, 2019, 05:40:21 PM »
Thank you all for your interest  :ThumbsUp:

George, I am mostly making this up as I go along. I agree that a bigger flywheel will improve slow running however the original plan for this engine was to power a model tractor which will restrict the flywheel size and will also probably require fairly high rpm. In the design of the big end I considered a maximum speed of 6000 rpm. If it would idle at 2000rpm that would be ok, lower would obviously be better. I am still not sure that I am getting combustion directly from the fuel injection or vis leakage past the piston and carburation  :headscratch: If it was direct combustion I would expect a much quicker start with a hot engine but there is always quite a delay and hence quite a quantity of fuel injected. The gunge that comes out of the breather pipe seems to thin to be the lubricating oil so there must be a significant proportion of diesel oil.

There was a compression ignition engine that used an ingenious trick to avoid high pressure injection:

http://www.eldensengines.com/homebrewhvid/homebrewhvid.html


Best regards

Roger

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #289 on: May 12, 2019, 10:25:16 AM »
I bought the engine back in from the garage to think about the next steps. When I turned the engine over there was an obvious compression leak  ::) A quick look showed that the injector O ring had blown out but that there had also been some combustion afterwards  :headscratch: I need to improve the sealing system at this point however it needs to seal on the nozzle not on the body  :thinking: I then removed the head to see if there were any clues about the state of combustion but nothing was obvious  ::)
Best regards

Roger

Offline cnr6400

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #290 on: May 12, 2019, 02:05:01 PM »
Maybe try a soft copper ring Roger? it would likely stand the pressure better than rubber rings. Just food for thought.

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #291 on: May 12, 2019, 02:13:49 PM »
Thank you Jeff(?).

That's the direction I am thinking however I will need to modify the head and possibly the injector. As I am thinking about a new injector design that may be less of a problem  :thinking:
Best regards

Roger

Offline fumopuc

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #292 on: July 16, 2019, 07:17:37 PM »
Hi Roger,
a member of our German forum has build this Diesel Lanz.
May be you enjoy it also to see it running.
« Last Edit: July 20, 2019, 08:00:25 AM by fumopuc »
Kind Regards
Achim

Offline doubletop

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #293 on: July 19, 2019, 09:56:23 PM »
Roger

I'd suggest that an O ring used in the way you have will always blow out. I think you need an O ring, or two, in an annular groove on the shaft that goes into the head. A couple of 1mm O rings should do it.

Pete

?To achieve anything in this game, you must be prepared to dabble on the boundary of disaster.? - Stirling Moss

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #294 on: July 29, 2019, 07:41:08 PM »
Thank you all for your comments  :ThumbsUp:  :ThumbsUp:

Looking more closely at the injector seal I hadn't cut the chamfer deep enough so there was not enough support for the O ring. The technique had worked fine with the other cylinder heads.

Very nice video Achim  :)  :wine1: I have seen a few versions of the Lanz Bulldog but most suffer from trying to keep the hot bulb hot  ::) One version I saw used a concealed automotive diesel glowplug to maintain combustion  :thinking:

I have decided to make some more trials with mushroom style injectors (over on the fuel injection thread) as I still tend to think I am getting too much penetration and not enough atomisation with the current design  :headscratch:
Best regards

Roger

Offline bent

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #295 on: July 30, 2019, 08:48:55 PM »
I am in awe of your persistence, Roger!  Hoping to see it running trouble-free one of these days. :popcorn:

Offline Craig DeShong

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #296 on: July 31, 2019, 10:01:02 PM »
Roger,  iíve Been silently following along, watching you persevere through the ups and down of this project.  I canít comment because I know nothing about diesels but I admire your tenacity, I might have given up long ago.  Seems like you are headed toward success as as Ďbentí just stated, I too look to see it running problem free.
Craig