Tiny true diesel engine

A friend of mine is trying to work out a design for a model engine, - multi cylinder, running on conventional diesel oil. He says he has
looked everywhere but has yet to find any references.
Has anyone ever tried to make one or heard of one even. I am not talking about the alloy plane engines running on ether mixes and I realise the problems associated with high injection pressures, etc. but what is the smallest true diesel anyone has heard of?
Thanks George.
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The last couple of issues of Model Engineer have had details of a model of Rudulf Diesels early prototypes in 1:10th scale. Bore is 30mm, stroke 40mm, the injector pump works at over 150bar :eek: Fantastic bit of model engineering
Hopefully the following link should take you to some pictures of the model, its the one towards the bottom and starts with an etching of the original
http://www.model-engineer.co.uk/albums/member_album.asp?ag78
Jason
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Suggest starting with this months "Model Engineer", but it's not tiny, but it is a true Diesel Diesel!
30mm bore x 40mm stoke
Steve
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Hope I'm not trying to teach granny to suck eggs but the problem with small diesel engines is the cylinder volume/surface area ratio and the heat loss that takes place. Go small enough and it'll lose too much heat to self ignite. That's why very large diesel engines are so fuel efficient because the cylinder volume is massive compared to the surface area and very little heat loss takes place.
I have no idea where the limit lies on how small you can go though. I imagine the compression ratio would have to increase substantially as cylinder size goes down to compensate for heat loss and eventually the pumping losses would be so high it would produce little power. Car sized diesels use CRs of 18 to 22. Big ship diesels can go as low as 14:1 and still self ignite ok. That's barely more than a petrol engine compression ratio. I imagine at model engine sizes you might need closer to 30:1 to generate ignition.
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Dave Baker



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Do a search for the Dux built by Martin Alewijn. The plans were published in Simply IC magazine.
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