Author Topic: Compression ignition engines  (Read 238 times)

Offline Kegan

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Compression ignition engines
« on: May 03, 2024, 01:57:32 PM »
Hallo one and all.

I am very interested in diesel engines. I have read multiple articles on true diesels needing atomization of the fuel and very high pressures to ignite. Then I have read articles on compression ignition with fuels like ether  that combust at lower pressures but the fuel is hard to come by because legalities and lack of interest etc. I want to build a compression ignition engines. Stationary horizontal type engines. I am planing on doing a few steam engines first, possibly a few hit and miss types. I eventually want to build a replica of an engine that my uncle had on his farm, a National Gas and Oil engine. I am just wondering what other easily come by fuels are there that can be used instead which don't need to be atomized and don't require such high pressures.

Any thoughts and ideas?

Thank you

Offline Jasonb

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Re: Compression ignition engines
« Reply #1 on: May 03, 2024, 02:15:37 PM »
I'm making a National Gas engine at the moment, have it on a vapour carb and vapour tank that uses regular pump petrol. No Pressure and no atomising

With a change of carb it would run fine on liquid petrol or as I prefer Colemans fuel (camping stove fuel) No pressure and the carb easily atomises the fuel

Change of valve and swapping out the spark plug for a hot tube it should run OK on propane, propane tank ha sit's own pressure so no pump needed and as it is a gas no atomising needed

Bit more fiddling about and it could be made to run on paraffin (kerosine) but I have another set of castings for a Robinson Oil engine that will be set up to run that along with hot tube ignition. Fuel flows under gravity and the heat of the engine vapourises the liquid.


Offline Kegan

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Re: Compression ignition engines
« Reply #2 on: May 03, 2024, 02:37:54 PM »
Thank you

Offline lohring

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Re: Compression ignition engines
« Reply #3 on: May 03, 2024, 04:01:15 PM »
Model "diesel" engines have been around a long time.  See https://forums.modelflying.co.uk/index.php?/topic/47758-glow-to-diesel-conversions-lets-see-them/ for newer conversions.

Lohring Miller

Offline ddmckee54

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Re: Compression ignition engines
« Reply #4 on: May 03, 2024, 04:39:33 PM »
Have you looked into model aircraft diesel fuels?  They are readily available on-line, shipping to your location might be expensive though.

Offline Roger B

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Re: Compression ignition engines
« Reply #5 on: May 03, 2024, 05:03:46 PM »
That’s quite a wide ranging question:

Working true Diesels in small sizes are possible, but often a bit messy. There are other similar engine types, the HVID and Hesselman versions that avoid high pressure fuel injection.

https://www.gasenginemagazine.com/gas-engines/Hvid-Engine-Combustion/

Elden Du Rand produced a HVID and was working on a true diesel when he died. I’m not sure if the websites still exist.

https://www.smokstak.com/forum/threads/homebrew-diesel-built-by-elden-durand-2018.184471/

Find Hansen produces working diesels but he does not release much information and it is not clear to me if he is using added ether or not.

https://www.findsminimodelhotbulbengines.dk/index.html

I can buy Diethylether in the pharmacies here (Switzerland) but it is not available in many other countries as it can be used in the manufacture of recreational drugs. There are other options such as John Deere starting fluid and ‘Wynns Start You Bastard’.

I have made a 20 cc true diesel with a compression pressure of around 40 Bar and an injection pressure of around 100 Bar. The development is scattered over several threads on MEM. The recent ones are here:

https://www.modelenginemaker.com/index.php/topic,10605.0.html

https://www.modelenginemaker.com/index.php/topic,10603.0.html
Best regards

Roger

 

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