In-line Diesel Engine Model

A thought that has just come to me.

Scaling the nozzle holes would entail drilling holes about 0.02 mm dia, which will be difficult. And, to compensate for the poorer atomisation resulting from a lower injection pressure (probably originally circa 1,000 psi - 680 bar) why not increase the compression ratio, to improve the chances of initiating combustion? This may well mean retarding the injection timing a little, but should reduce ignition delay, and so make the engine a little quieter.

Howard

I'm pleased that this topic has raised so much interest and so many thoughtful contributions.

I don’t think I want to comment further on the various historic ignition processes. My concern really is with building an operating model which should be capable of powering an Excavator. The 3 VQBN was specifically developed to power the Ruston-Bucyrus 19-RB.

As Howard has mentioned noise' part of my wish is to end up with a machine which has the atmosphere of the original, which probably means the noise as well.

I have used the ME Index thoughtfully supplied by Phil (Weary) and there are several entries in volumes 210 and 211 about George Punter’s Lister build. I believe that his earlier 4 cylinder engine may relate more to my hopes.

The video of it is at

**LINK**

On the assumption that I will eventually produce a working model I will be only too pleased to shoe it here.

Jerry

Howard, I felt that trying to produce a multi hole injector in this size would be extremely difficult and at a high risk of getting blocked. I am using a pintle type with a hole of 0.35mm which appears to give god atomisation at around 60 Bar. The other consideration is that the combustion chamber will be smaller so less penetration will be required. I doo have a concern that the fuel will just end up on top of the piston.

**LINK**

A construction article for 'DUX' - a 9.5cc single cylinder Diesel with solid fuel injection, designed by Martin Alewijn - appeared in Strictly IC magazine from Dec 2000/Jan 2001 to Aug/Sep 2001 (issues 78 to 82). I understand that back issues of the magazine are still available from the publisher at www.strictlyic.com.

As I recall from the article, the issue of drilling a very small hole in injector was avoided by making a very fine scratch in the conical seat of the injector needle, which then provided a path for the fuel and the necessary atomisation.

Anthony

Edited By LADmachining on 17/01/2018 10:32:10

Going back to the original question:

How big is the engine going to be? The one in the video is around 30mm bore and 38mm stroke. (it wasn't built by George Punter, but by W7CS. It's just liked on George's YouTube).

The horizontal valves suggest that the engine you want to build has a clearstory combustion chamber which should make things a little easier.

The injection pump on the engine in the video is ~4mm bore and ~2mm stroke. This seems rather big unless he is allowing for a lot of leakage. Injection pressure is ~80Bar which is the range I am trying to achieve.

If you go ahead with this I would suggest that you make a bar stock single cylinder version to learn and experiment on.

Best regards

Roger

Hi Roger,

Thanks for your notes. I have been following your 2 threads on MEM about you investigativr work. I'm afraid I am rather late to this particular party.

On MEM I have a 'new' thread which is rather scanty at the moment as I am just at the design stage of my 19-RB project. As to size that's not yet determined; it can only be as big as the model which it is to power will allow and the size of that depends on how much room it will take up in the workshop.

You will see that on this site the thread has been diverted into a debate about definitions of the term 'Diesel' which whilst being interesting has no value to me in trying to build a miniature version of a Ruston & Hornsby machine. My understanding is that R-H machines were 'solid injection' which they described as 'airless injection'.

Jerry

The model Lister 6/1 Diesel engine is a diesel in that it does not have any form of spark ignition and relies on compression for instigating the combustion process. It is a four stroke engine and does use an injector pump with a manual by pass valve. The injector made use of a modified gas jet and injects into a pre combustion chamber as does the full size engine. I have only ever made one single cylinder Diesel engine but have made 29 other petrol engines from 6.5 cc to 150 cc , singles ,twins, threes and four cylinders. As you can see my experience of Diesel engine construction is limited and it is a continuous learning process but if I can help you Jerry in any way I will be pleased to do so.

George Punter.

Thank You George ( Four Stroke Fred),

Sorry I have been so slow in responding to your post of the 12th, I had to search back through several pages of previous posts to reach it. It seems the ME forum has been very busy during the past 8 days !

Your offer is very welcome as yours seems to be the only example I can find of anyone building a successful in-line diesel engine. I am not sure that I made it clear in my earlier posts that I am building a replica of a Ruston-Bucyrus shovel, at the moment the R-B machine is not at all certain as it will in the end depend on the availability of detailed informattion. However since the last steam machine was sold in the 1930's every one has been available with Diesel power.

A I am sure you know Rustons supplied Ruston engines until the partnership with Bucyrus ended but my understanding is that Ruston and Lister engines were similar in many ways.

As you have been successful in getting your engine to work I am certain you could provide me with assistance in many areas, especially fuel injection.

I will send you a PM

Best regards

Jerry

“ I had to search back through several pages of previous posts to reach it.”

A tip. Go to ‘My Posts’ and it will show your posts.

Alternatively, search for the thread topic.

Far easier than trawling through pages of posts/threads.

Jerry I have only ever made the single cylinder Diesel engine but have seen a four cylinder working model some where on the forum or YouTube. My approach to making model I.C. Engines has always been from a practical point of view and not so much on the " theory". In my book if the I.C. engine works and it doesn't have a spark plug to ignite the mixture, it is a Diesel engine! The difficult parts to make are the injector and injector pump as most if the other parts are similar in structure to any other four stroke petrol engine. My main problem was the injector jet hole and on my engine I used a gas jet.

George.

I made a 22 cc compression ignition four stroke engine with variable compression ratio controlled by moving the crankshaft up and down. For fuelI used a mix of paraffin with 10% lube oil and about 1-2% easy start. It was successful and flew a model aircraft quite well. It has a lovely sound especially when opening the throttle with a very distinct Diesel Knock. I displayed it in a model at Elvington about 1999, quite a number of people who thought they knew it all told me that my engine needed looking at because you could hear the big end knocking.

it f I'm not saying how I moved the crank shaft up and down but will leave you guessing.

Bob I think you you may have made a non concentric crankshaft bearing that when rotated raised or lowered the con rod,piston unit. I remember seeing a model aircraft flying near Malborough ( Wiltshire) with a commercial prototype four stroke Diesel engine and that used a variable compression unit in the position where the spark plug would have gone - it also sounded good.

George.

You are on the right track Fred. It would only be possible to do this with a vertical or possibly Vee formation engine.