What is a Diesel Engine ?

[The Ignoble Troll]

Sorry - - - - I find these diagrams quite hard to read - - - is there any way that larger versions could be made available - - - even as a link - - - please?

TIA

You can always right click and open preview then zoom in either with the mouse scroll wheel + ctrl or ctrl + the + button.

 

[peterl95124]

There are a couple of other points to consider with modern electronic fuel injection systems.

Spark ignition engines often use various stratified charge systems to allow leaner mixtures and higher compression without pre ignition/knocking. Spark ignition engine fuels are still designed to have poor self-ignition qualities = high Octane rating.

High speed turbocharged automotive diesels now split the injection into several stages to limit the maximum cylinder pressure, moving closer to Diesel’s original concept. This allows for an initial pilot injection which reduces the need for good self-ignition properties = high Cetane number.

Things become even more interesting when you look at the Mahle Turbulent Jet Ignition (TJI) used in F1 cars:

https://www.motorsportmagazine.com/articles/single-seaters/f1/ferraris-formula-1-jet-ignition/

Or the Homogenous Charge Compression Ignition (HCCI) Engines which are neither spark ignition nor Diesel:

https://www.intechopen.com/chapters/43660

Roger, thanks!, I found the F1 article very interesting! (but its still spark-ignition), but the HCCI article is about how model airplane diesel engines have always worked and is neither interesting nor promising IMHO its just another unnecessary research project, YMMV...
Pete.

 

[Roger B]

All these developments are derivatives, the TJI can be seen in the HVID ‘diesel’ design as well as the early German Diesel pre combustion chambers that were an attempt to replace the air blast injection.

The HCCI is a valid development if it can do away with the complicated high pressure injection systems and still deliver flexible load and speed control.

Model aircraft ‘diesel’ engines generally run under fixed conditions driving a very benevolent load, a propellor. As the speed drops the load drops. The first model aircraft Diesel engines had fuel injection but the developer, Eisfeld, found he could get similar results with carburation.

A further development was the Lohmann 18cc ‘diesel’ moped. This was able to deliver flexible load and speed but required the operator to adjust the fuel mixture and compression ratio accordingly.

https://onlinebicyclemuseum.co.uk/1951-lohmann-18cc-diesel-engine-new-old-stock-unused/

The HCCI development work is using different techniques, such as exhaust gas recirculation and pre heating of the intake air/mixture to obtain flexibility. I wait to see if it will eventually offer a cheaper engine with improved emissions.

 

[Nerd1000]

The ideal with HCCI is to have a cool, lean burn. Lean burn like a diesel is ideal for fuel economy, but the combustion of a diesel is very hot around the fuel droplets hence excessive NOx emissions, and also the burn conditions can be rich in some areas of the cylinder at high loads (= black smoke). If you can manage to ignite a lean homogeneous charge it burns slowly and at comparatively low temperature, with minimal emissions. The challenge is doing that in a controllable fashion. Mazda with their skyactiv-X design managed a kinda-sorta version by using a small region of normal spark ignition combustion to compress the lean homogeneous charge to ignition. But it doesn't seem to have been much of an improvement on a modern spark ignition engine.

 

[Steamchick]

Hi Lloyd: re: "pour some gas on a rag and hold it over the diesel air intake." - I had forgotten the mechanic did that when I was a kid to get a diesel engine started..
Nostalgia of a Saturday morning job at a machine shop....

I remembered it once on a VAN with a diesel, where the battery was a bit tired and the glow-plugs didn't automatically switch ON with ignition ON... before cranking. We had run out of "Easi-start". but we had some paint solvents handy, and splashed some on the air filter, fitted it and started the engine. Went like a racer for a half minute until the fumes had all been consumed - then was fine.
Fixed the flat battery and glow-plug relay and never needed that again.
K2

 

[ajoeiam]

You can always right click and open preview then zoom in either with the mouse scroll wheel + ctrl or ctrl + the + button.

Hmmmmmmmmmm - - - might be possible in Chrome - - - - that doesn't happen in Firefox - - - sorry.

 

[The Ignoble Troll]

Hmmmmmmmmmm - - - might be possible in Chrome - - - - that doesn't happen in Firefox - - - sorry.

Weird, it should. Even works in IE.

 

[The Ignoble Troll]

Weird, it should. Even works in IE.

Try right clicking and opening the image in it's own tab?

 

[ajoeiam]

Try right clicking and opening the image in it's own tab?

Even then!

(I seem to be considered someone who doesn't have any idea how to maneuver the internet - - been on it since 1986 so that's not true either!)

Only option is to download the image, save it and then use a graphics program to enlarge it.
Problem with that is that the text doesn't necessarily scale well - - - which is why I asked for urls for source docs. (they seem to not be available)

 

[The Ignoble Troll]

(I seem to be considered someone who doesn't have any idea how to maneuver the internet - - been on it since 1986 so that's not true either!)

I'm sorry, that was not the vibe I meant to give off. Genuinely made no assumptions on your abilities, the enlarge shortcuts are things lots of people don't know about so I was just trying to help. It's all good.

 

[minh-thanh]

Weird, it should. Even works in IE.

That is correct. It is the zoom function of the windows operating system.

ajoeiam said:
(I seem to be considered someone who doesn't have any idea how to maneuver the internet - - been on it since 1986 so that's not true either!)

He is just trying to help, no one can know how much you know about the internet and computers.

 

[minh-thanh]

Hmmmmmmmmmm - - - might be possible in Chrome - - - - that doesn't happen in Firefox - - - sorry.

Here ...Firefox : zoom

Image link :
https://www.homemodelenginemachinis...-2-stroke-will-it-ever-work.31110/post-413561