Author Topic: My new project ...Small diesel engine . (Read 20369 times)

Minh Thanh · « **on:** May 24, 2024, 11:41:39 am »

Hi Everyone !
My new project :

Minh Thanh · « **Reply #1 on:** May 24, 2024, 11:51:12 am »

More pictures so far : But I can't attach more pictures !!!??

Roger B · « **Reply #2 on:** May 24, 2024, 12:01:21 pm »

You should be able to attach 8 pictures per post but the size is limited.

Alyn Foundry · « **Reply #3 on:** May 24, 2024, 12:27:24 pm »

Hi Minh.

I will be following your progress with great interest, we also decided earlier this year to build a scale model of Rudolph Diesel’s first engine. Although this particular design failed originally we felt that with the knowledge we have today a working model was achievable.

Since making the patterns I have suffered a stroke which has greatly reduced my abilities in many areas. This project will be my recovery plan….

I see you have chosen to make a model of the first, successful Diesel engine as built by MAN in Germany.

Good luck and

Graham.

Minh Thanh · « **Reply #4 on:** May 24, 2024, 12:50:06 pm »

Quote from: Roger B on May 24, 2024, 12:01:21 pm

You should be able to attach 8 pictures per post but the size is limited.

Ok, thank you, I will reduce the size of the image .

Minh Thanh · « **Reply #5 on:** May 24, 2024, 12:56:46 pm »

Hi Graham.!
Thank you.
I hope you get well soon and continue with the project

Minh Thanh · « **Reply #6 on:** May 24, 2024, 01:10:10 pm »

Hi All!
More pictures so far

Minh Thanh · « **Reply #7 on:** May 24, 2024, 01:14:59 pm »

and more pictures ...

pirmin · « **Reply #8 on:** May 24, 2024, 03:06:33 pm »

Excited ! When i am done with my otto build i will also get back gto my Diesel project. luckily i have already sorted the injector and pump design, so i will see if i make a design of my own or go from the known designs from Find hansen or other modellers !

Cool to have you here !

Roger B · « **Reply #9 on:** May 24, 2024, 07:49:53 pm »

What Diesel are you planning? I have been on a rather lonely journey up to now. I met up with Minh via YouTube and there are a couple of other diesel builders on HMEM.

Minh Thanh · « **Reply #10 on:** June 06, 2025, 12:10:20 pm »

Hi All !
An update :

Bear · « **Reply #11 on:** June 06, 2025, 02:01:58 pm »

Coming along very nicely.

Minh Thanh · « **Reply #12 on:** June 15, 2025, 12:29:20 pm »

Quote from: Bear on June 06, 2025, 02:01:58 pm

Coming along very nicely.

Thank you !
Hi All
An update :

Mike R · « **Reply #13 on:** June 15, 2025, 04:47:24 pm »

Looking good!

Minh Thanh · « **Reply #14 on:** June 27, 2025, 12:02:19 pm »

Quote from: Mike R on June 15, 2025, 04:47:24 pm

Looking good!

Thank you !

Hi All !
Update :
I designed the motor and during the machining process I thought ...thought....and decided to change the gear parameters - Changing the gear parameters will change the dimensions of the other parts a lot - by measuring, ....step by step, machining and measuring and checking....
I finished a few parts last week but I haven't updated because I'm not very confident about the decision to change the gear parameters
Now everything is assembled together and it's pretty good and smooth
Everything went as I expected.

Minh Thanh · « **Reply #15 on:** June 27, 2025, 12:05:58 pm »

More :

CI · « **Reply #16 on:** June 27, 2025, 02:05:16 pm »

That has a great old-school look to it.
Nice work !
.

Roger B · « **Reply #17 on:** June 27, 2025, 06:12:22 pm »

Glad to see you continuing on this

The cross head guide system is a good solution the conrod clearance problem on long stroke engines

Minh Thanh · « **Reply #18 on:** July 12, 2025, 02:40:01 pm »

Quote from: Casting Iron on June 27, 2025, 02:05:16 pm

That has a great old-school look to it.
Nice work !
.

Thank you !

Minh Thanh · « **Reply #19 on:** July 12, 2025, 02:40:20 pm »

Quote from: Roger B on June 27, 2025, 06:12:22 pm

Glad to see you continuing on this The cross head guide system is a good solution the conrod clearance problem on long stroke engines

Minh Thanh · « **Reply #20 on:** July 12, 2025, 02:48:02 pm »

Hi All
Update :
All parts are pretty smooth

CI · « **Reply #21 on:** July 12, 2025, 02:49:43 pm »

Looks great !
I like those helical gears.
.

Zephyrin · « **Reply #22 on:** July 12, 2025, 06:35:59 pm »

very nice project to follow.
it looks to be a very sturdy construction, what are bore and stroke ?
I do have your plan of a previous diesel engine, but I'm intimidated by the injector, and haven't yet decided to take the plunge...

Sanjay F · « **Reply #23 on:** July 12, 2025, 06:37:56 pm »

Looks great, has a standard and rod like an early 20th century engine, well done

Minh Thanh · « **Reply #24 on:** July 13, 2025, 04:44:16 am »

Casting Iron, Zephyrin , redhouseluv
Thank you very much !

Quote from: Zephyrin on July 12, 2025, 06:35:59 pm

very nice project to follow.
it looks to be a very sturdy construction, what are bore and stroke ?
I do have your plan of a previous diesel engine, but I'm intimidated by the injector, and haven't yet decided to take the plunge...

Bore: 19 mm, stroke: 40 mm
Injector: I don't care too much about the style, shape, size, angle...,....of the needle and injector. What is really necessary and sufficient - for me - is that the injector must be sealed.

One injector style - It is exactly like the engine valve (intake-exhaust). - hope it gives you an idea ....

Minh Thanh · « **Reply #25 on:** July 21, 2025, 04:12:01 pm »

Hi All
Update :

CI · « **Reply #26 on:** July 21, 2025, 04:15:52 pm »

Looking good !
I like that oiler system.
.

cnr6400 · « **Reply #27 on:** July 22, 2025, 01:02:50 am »

Minh Thanh · « **Reply #28 on:** July 28, 2025, 04:54:59 pm »

Quote from: Casting Iron on July 21, 2025, 04:15:52 pm

Looking good !
I like that oiler system.
.

Quote from: cnr6400 on July 22, 2025, 01:02:50 am

Thank you !

Hi All !
Update :
When I change the gear parameters it affects the size...of other parts, and I'm lazy to draw, so I measure, check and do each part step by step.
So far everything is ok

cnr6400 · « **Reply #29 on:** July 29, 2025, 12:30:54 am »

Minh Thanh · « **Reply #30 on:** August 18, 2025, 05:23:24 pm »

Quote from: cnr6400 on July 29, 2025, 12:30:54 am

Thank you !

Hi All !
An update!
I'm sorting out, thinking...everything related to the model engine - more crazy than I know how to do it...,
So progress is a bit slow
Some pictures...for now

Kim · « **Reply #31 on:** August 18, 2025, 05:35:58 pm »

It looks really nice, Minh!

You must be getting close to a first run?

Kim

CI · « **Reply #32 on:** August 18, 2025, 05:38:58 pm »

It looks great !

.

Minh Thanh · « **Reply #33 on:** August 18, 2025, 05:56:54 pm »

Quote from: Kim on August 18, 2025, 05:35:58 pm

It looks really nice, Minh!

You must be getting close to a first run?

Kim

Thank you Kim !
Yes, just water pump and fuel tank and the engine is done
Some tweaking and excitement for ...

Quote from: CI on August 18, 2025, 05:38:58 pm

It looks great !

.

Thank you !

Roger B · « **Reply #34 on:** August 18, 2025, 07:05:22 pm »

Looks great

good luck for the first start

Minh Thanh · « **Reply #35 on:** September 11, 2025, 04:58:57 am »

Hi All !
Update..
just a notice .
The engine is done and it runs but not good .
I am working on the injector issue
With this engine I tried to limit the fuel flow to the smallest possible (smallest I can do - for now,..future = unknown

) by making the pump cylinder diameter 1.75mm so I am trying to solve the atomization and have some improved
I will update with pictures and video when everything is done, about 1 week from now

Admiral_dk · « **Reply #36 on:** September 11, 2025, 06:51:35 am »

I wish you all the luck with your endeavors and hope for a satisfyingly result.
I know it is not easy - but as you are one of the few I know of, who have made running Model sized Diesels Engines that runs

Per

CI · « **Reply #37 on:** September 11, 2025, 10:56:32 am »

It is quite a challenge, no doubt, to get an engine like that wrapped up.
Best of luck on it; I am sure you will prevail in the end.

.

Minh Thanh · « **Reply #38 on:** September 14, 2025, 12:47:46 pm »

CI , Admiral_dk , Thank you !

An update:
The engine ran pretty good and,,..suddenly lost compression
I checked and the condition is the intake valve is not sealing - This is the first time I have encountered this condition

I will rebuild a new cylinder head and new injector with a little change....which i think would be better , and it will be the standard size for my other projects

CI · « **Reply #39 on:** September 14, 2025, 02:22:24 pm »

To get an engine of that complexity to run in any fashion is a significant achievement.
I hope to build a diesel one day, and so it is good that others can perhaps define the difficulties involved.

.

Admiral_dk · « **Reply #40 on:** September 14, 2025, 08:50:34 pm »

Looks like you need to change Gasket Material

Great to hear that it ran well just before the mishap

Per

Zephyrin · « **Reply #41 on:** September 14, 2025, 09:19:05 pm »

how come there is so much soot in this combustion chamber, certainly no good for valve sealing...
but I'm sure you'll manage to get it running, apart from you, very few people can do it!

samc88 · « **Reply #42 on:** September 14, 2025, 09:29:58 pm »

Congratulations on getting it running, Im sure you will sort the teething issues out swiftly. Are you running on pump diesel? Not quite the same but when running my no.12 stove on diesel it is much sootier than if burning parrafin/ kerosene, would the fuel make a difference in this engine with sooting up the valves?

Mike R · « **Reply #43 on:** September 14, 2025, 10:45:34 pm »

Congratulations on a running engine, working through the issues is all part of the fun. Looking forward to hearing more about this engine from you.

AlexS · « **Reply #44 on:** September 15, 2025, 09:10:49 pm »

One step further!

Maybe you can make a head gasket with a sheet of CNAF. Resistance to temperature range up to 400 deg C or higher. CNAF include NBR material resisitance to oil/fuel and have aramid fibers for strength. Pressure sealing around 70-150 bar.

Roger B · « **Reply #45 on:** September 20, 2025, 08:04:23 am »

Congratulations on the first run

I have had a couple of occasions where valves have stopped sealing due to a small bit of something on the seat. A good clean up and a light regrind solved the problem.

What injector design are you using on this engine?

Minh Thanh · « **Reply #46 on:** September 20, 2025, 01:40:54 pm »

CI , Admiral_dk ,Zephyrin , samc88, Mike R ,AlexS, Roger B
Thank you very much !

I used the same injector as I did before, the problem is that the diameter of the pump is now only 1.75mm so the atomization of the injector is not good - But when the engine is running, there is very little - almost no excess fuel sprayed out of the exhaust and that is a pretty good result - Engine cylinder diameter 19mm
The real problem of the loss of compression is my stupidity. Due to my carelessness: the valve springs are almost not pressing the valve into the seat.
I rebuilt the new cylinder head with a few changes:
- Larger exhaust: better suited for large exhaust volume
- Smaller hole for the injector - because I will make smaller injectors , I'm planning on making the nozzle diameter around 0.7 or 0.8mm and am doing some testing ... ,and it also meets some intentions for my future diesel projects.
- Also make the valve pressed into the seat with a spring force
- Change the height of the combustion chamber to better fit the new gasket.

AlexS · « **Reply #47 on:** September 20, 2025, 03:39:51 pm »

How did you design the pump with variation of fuel flow? With a rotation spill height?

Minh Thanh · « **Reply #48 on:** September 20, 2025, 04:39:07 pm »

Hi AlexS .
My diesel engine is small and the fuel volume is about 0.5 mm3 so the plunger stroke is very short, about 0.5mm -> controlling the inlet port is quite difficult, almost impossible with my ability (I have been thinking to make it better but there is no way to consider it feasible , may be in the distant future ...). So I use the method of changing the plunger stroke to control the fuel volume.

Minh Thanh · « **Reply #49 on:** October 10, 2025, 01:35:09 pm »

Hi All
Just a small announcement
The engine runs, sometimes it runs well sometimes it doesn't
Currently the injector is 0.7 mm
It seems that the smaller the diameter of the pump cylinder ( 1.75 mm ) the more troublesome the problem becomes...
I don't have much updates because I need to focus on finding out the reason...
I'm still testing... why ??
I will update when the engine is running ok .

CI · « **Reply #50 on:** October 10, 2025, 08:23:31 pm »

Minh Thanh · « **Reply #51 on:** November 10, 2025, 01:53:20 pm »

Hi Everyone!
It's been a month....
The engine has been running for quite a while now but I haven't updated it yet, because when I want to take pictures of the engine I have to clean it.... thoroughly. So I decided to do a lot of experiments with it to clarify the issues that I don't understand
- 5 times changing the pump cylinder diameter. More than 10 times changing the injectors
- A few times changing the cam lobes
- More than 100 times starting the engine
- More than 15 times it runaway
- Countless times changing and adjusting
I probably pushed it to the limit of the material I used for bearings, crankshafts...
....
And I also learned more about small diesel engines.
Pictures of my 10cc diesel engine

https://www.youtube.com/shorts/FFdLddoP7jE

cnr6400 · « **Reply #52 on:** November 10, 2025, 02:22:34 pm »

Admiral_dk · « **Reply #53 on:** November 10, 2025, 08:14:38 pm »

My first thought watching the Video - it runs very well (maybe a little fast)

Towards the end of the Video - it slows down - is that a problem or just running out of fuel ?

Per

Mike R · « **Reply #54 on:** November 11, 2025, 02:15:49 am »

Congratulations on the fine running engine. 10cc is quite small for a real injected diesel. Quite the accomplishment.
Please do share some of your successes and failures with the various pump diameters, injectors, cam lobes, etc.
I'm very interested.

Minh Thanh · « **Reply #55 on:** November 11, 2025, 10:03:27 am »

cnr6400 ,Admiral_dk, Mike R Thank you !

Admiral_dk ! Engine is low on fuel.
Mike R !
Give me a moment to sort out some things I already know......,( I am sorting out the machinery, tools, materials...Get rid of useless things or parts that have been done wrong,...)

CI · « **Reply #56 on:** November 11, 2025, 11:51:02 am »

A great effort, and very nice looking engine.
Congrats !

Zephyrin · « **Reply #57 on:** November 11, 2025, 02:29:02 pm »

congratulations for this new diesel engine at such a tiny scale...running well and looking realistic !
There aren't that many people capable of doing that.

Roger B · « **Reply #58 on:** November 15, 2025, 03:14:52 pm »

That's running well without much much black gunge from the exhaust. Small diesels seem to be rather messy

Are you able to vary the speed much? I have found that there tends to be 'sweet spot' where it runs quite well but does not offer much change of speed.

Have you tried adding a load to see how it will run when working? That will be one of my next trials.

I haven't dome much with my 4 stroke diesel for a while as I am working on the Junkers CLM 2 stroke diesel.

Minh Thanh · « **Reply #59 on:** November 17, 2025, 11:02:33 am »

Zephyrin , Roger B Thank you !
This engine is a completely new design for me : governor , the cross head guide system , gear system , ... and I really like this type of engine , so ...
Yes it is possible to change the speed by fixing the governor -> that is how I determine if the engine is running well or not before I install and adjust the governor ( the previous engine I did also had adjustable speed ) - not much but it is easy to see . I wanted to know how the governor works on this 10 cc diesel engine so I had to install the governor .
About load test : my load is the drill that I use to start the engine - about a few times . Personally I feel the engine seems to run better under load .
- 'sweet spot' : Yes definitely.

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Author Topic: My new project ...Small diesel engine . (Read 20369 times)