Mini diesel engine.

[Mechanicboy]

Simple answer is heat, heat is lost to the cylinder walls, piston, head and the fuel. The smaller the cylinder the less heat energy you will get from the air charge. Physics don’t scale very well, especially when it comes to thermal dynamics.

In a model diesel engine with carburator from 0,1 ccm who are smallest and larger is simplere to atomize the fuel in smaller fuel drops and mix into the air before entering in the cylinder and the fuel mix is allready gaseous heated by engine before compression is started to heat up the air. Also the small injector is more difficult to atomize so finer and smaller drops to heat up so quickly to form as gaseous fuel in the small engine who has large heat of loss in surfaces.

 

[Gedeon Spilett]

Thanks for the answer, Chaffe, the loss in heat in a tiny engine makes sens for me, although I read somewhere in this very informative thead that the compression is adiabatic !

 

[ajoeiam]

In a model diesel engine with carburator from 0,1 ccm who are smallest and larger is simplere to atomize the fuel in smaller fuel drops and mix into the air before entering in the cylinder and the fuel mix is allready gaseous heated by engine before compression is started to heat up the air. Also the small injector is more difficult to atomize so finer and smaller drops to heat up so quickly to form as gaseous fuel in the small engine who has large heat of loss in surfaces.

Hmmmmmmmm - - - sorry friend - - - I don't think your going to be using a carburetor in a diesel (compression ignition) engine.
Just doesn't work that way.
Possibly you were referring to an injection pump but that's not really a carburetor.

 

[Mechanicboy]

Hmmmmmmmm - - - sorry friend - - - I don't think your going to be using a carburetor in a diesel (compression ignition) engine.
Just doesn't work that way.
Possibly you were referring to an injection pump but that's not really a carburetor.

Are you sure model diesel engine doesn't to have the carburettor?

Read this link . Carbureted compression ignition model engine - Wikipedia

And here is the old Norwegian chain saw with carburettor and hot bulb.

 

[ajoeiam]

Are you sure model diesel engine doesn't to have the carburettor?

Read this link . Carbureted compression ignition model engine - Wikipedia

And here is the old Norwegian chain saw with carburettor and hot bulb.

Well - - - in reading your attached url - - - it does say - - - - 'no relationship
with actual diesel engines' .

I've run into a lot of different kinds of engines but never a high compression
otto cycle engine with hot bulbs.

Wonder why they would even want to make an engine like that chain saw
with the hot bulb. Maybe so that kerosene could be used.

Know that in extreme cold temperatures the 'gasoline' formulation is modified
so that everything works well.

I will - - - still - - - maintain that a real compression ignition engine does NOT use a carburetor.
(Notwithstanding certain anomalous variants!!)

 

[Mechanicboy]

I will - - - still - - - maintain that a real compression ignition engine does NOT use a carburetor.
(Notwithstanding certain anomalous variants!!)

Carburetor or injection is not important. They have one thing in common: Develop heat by compression to ignite fuel.

 

[minh-thanh]

Carburetor or injection is not important. They have one thing in common: Develop heat by compression to ignite fuel.

Let's focus on one type of injector diesel engine.!!

 

[Mechanicboy]

Let's focus on one type of injector diesel engine.!!

Minh-Thanh..
Calm down, there is no reason for you to be aggressive in the forum.

 

[awake]

That was aggressive? Seemed more like a desire to stay on topic for the thread.

In terms of fuel used, I think Minh said it would run on ether one.

 

[Donrecardo]

ajoeiam said:


Hmmmmmmmm - - - sorry friend - - - I don't think your going to be using a carburetor in a diesel (compression ignition) engine.
Just doesn't work that way.

This one does

 

[methuselah1]

I am new to this thread, so I'm probably only repeating what someone else will have already written. True diesel engines inject fuel into a compressed charge of air. Compression ignition engines use a very different fuel, and rely on compression to ignite a ready mixed charge instead. Hence the carburetter.

Misnomer as it is, aeromodellers always refer to this type as "diesel", even if that's incorrect; but when one AM speaks engines to another AM, they both know exactly what they're talking about. Paraffin burning motors, lubricated with castor oil, ignited by diethyl ether.

At the most basic level, these constituents are mixed 1:1:1, sometimes with a little amyl nitrate as a dope.

-Andrew UK

 

[ajoeiam]

ajoeiam said:


Hmmmmmmmm - - - sorry friend - - - I don't think your going to be using a carburetor in a diesel (compression ignition) engine.
Just doesn't work that way.

This one does

Hmmmmmmm - - - developed my thinking when this:

was a 'small' engine.

This was the workhorse:
http://www.tractordata.com/farm-tractors/000/7/3/731-massey-harris-44.html

(that one is looking a little under the weather)

and this one was parked (I played on it and made it go real hard but carefully - - - I had been warned that when it pulled very hard that it might start running backwards - - - so careful was the game - - LOL (this one pictured is is FAR better condition than the one we had))

this:

is a BIG engine (buts its a diesel - - - compression ignition - - - engine)

Your engine - - - it may be 'called' a diesel engine but for me - - - sorry a compression ignition engine that requires ether on a constant basis - - -
that's stretching the envelope just a bit too far.

It has been very interesting following the trials of getting an injection system working.

I'm following because the information might be usable in designing something like a 5 kW medium or maybe even a touch slower 'diesel' engine for power generation purposes.

 

[Donrecardo]

You wrote

Misnomer as it is, aeromodellers always refer to this type as "diesel", even if that's incorrect;

Diesel engine - Wikipedia
https://en.wikipedia.org › wiki › Diesel_engine
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression;

So what aeromodellers call it is not incorrect. regardless of what fuel it uses , as long as it ignites due to compression its a diesel

the picture above is of an engine that relies on compression to elevate the temperature till it ignites and it does have a carburetta

 

[ajoeiam]

You wrote

Misnomer as it is, aeromodellers always refer to this type as "diesel", even if that's incorrect;

snip
the picture above is of an engine that relies on compression to elevate the temperature till it ignites and it does have a carburetta

I didn't coin the first phrase.
Searching wikipedia research it is not.
We'll agree to disagree then - - - yes?

Maybe we should be striving to create the new improved wonderful version of the best electric motor.
Society - - - or at least some parts of it are hell bent on eliminating internal combustion engines - - - of any type!

 

[Mechanicboy]

Many people think that it is the injection that causes the engine to be called "diesel engine". No one clearly thinks that it is the compression heat itself that is the main source of igniting the fuel whether the engine has injection or carburetor. We also find the same in petrol engines that have direct injection (GDI), injection or carburetor, what distinguishes them from diesel engines is that an electric spark is used to ignite the fuel as the compression heat is not high enough to ignite the fuel. In the whole word, we separate the motors in 2 ways: Ignite by compression or ignite with electric spark. Not how we supply the fuel into the combustion chamber either it's a diesel engine or petrol engine.

 

[Donrecardo]

Many people think that it is the injection that causes the engine to be called "diesel engine". No one clearly thinks that it is the compression heat itself that is the main source of igniting the fuel whether the engine has injection or carburetor. We also find the same in petrol engines that have direct injection (GDI), injection or carburetor, what distinguishes them from diesel engines is that an electric spark is used to ignite the fuel as the compression heat is not high enough to ignite the fuel. In the whole word, we separate the motors in 2 ways: Ignite by compression or ignite with electric spark. Not how we supply the fuel into the combustion chamber either it's a diesel engine or petrol engine.

Exactly , and as the aero engine picture shows it relies on compression for ignition not injection which is why it can use a carburetta

 

[minh-thanh]

Mechanicboy.
I was reading another thread in this forum and elsewhere, and there was a debate about diesel, real diesel, compression-ignition, fuel injection or carburetor.... ,.. .. It's a problem that I don't want to happen again
So I want:

Let's focus on one type of injector diesel engine.!!

And now that you've got what you wanted...well done...go on .

 

[djswain1]

Minh-thanh started the thread, then designed and built his own diesel engine. No small achievement.... So on this this thread I think what he says goes and we keep this thread to fuel injected CI "diesel" engines.
Perhaps a new thread could be started for a more general discussion on compression ignition or diesel engines in all their various forms.
Cheers, Dave.

 

[Chaffe]

Some success with the “old” style injection pump, Minh-Thanh what injection pressure does your injection pump achieve? What pressure are you popping your injector at? Chaffe

 

[minh-thanh]

Hi Chaffe !
One question I can only answer: I don't have any pressure readings at the moment
Sorry !!
I will buy a pressure gauge and will check
When I made this diesel engine, the Covid epidemic situation increased, so my place was completely lockdown, I could only test the injectors and pump with the engine., I could only trial and error and do everything the best thing possible.
Until the epidemic situation showed signs of abating, I could only buy back a small copper pipe from a friend that he had left over, but I still couldn't buy a pressure gauge., again I can only test the injectors and pump with the my engine and based on my experience and judgment
Trial and error, adjust...... until the engine feels like it can "run"., and trial and error, adjust..... until the engine run
I can't watch your video