Diesel Cylinder Material

I'm proposing making a small compression ignition diesel as described in ME, Oct. 1977. It's made from bar stock., 3/8" bore. I'm hoping to use materials to hand.

The writer suggests KE805 for cylinder and piston with the piston hardened. This seems equivalent to En24 which I've not got, but I've plenty of mild steel and bits of En8.

I won't want to run the engine, (if it runs at all!), for long periods, it's really a build project. Will mild steel be OK for the cylinder and perhaps En8 for the piston?

Edited By Clive Brown 1 on 23/11/2022 09:19:03

Hello Clive,

Without doubt the best combination for a home built engine is a liner made from free cutting EN1a mild steel with a cast iron piston.

Lap the liner then lap the piston to fit. I have made several diesels using this combination with good success all with good compression and all run well.

There really is no need to use material that requires heat treatment - that will inevitably lead to distortion anyway.

Making a diesel is a satisfying project especially when it runs but the smaller the capacity is the more difficult to get that fit required between piston and liner for successful running. Not impossible obviously as many have been made but easier if it's larger. If you haven't got the right fit for decent compression it's unlikely to start let alone run as also many have found out.

If you haven't started yet may I suggest you start with something around 2 - 2.5cc.

The Owen 'Mate' and Chris Boll's 'Holly' spring to mind as ideal candidates.

If it's of any use I have described the building of mine on Model Engine Maker

Good luck with your project

Regards - Tug

Thanks Ramon for your informative reply. Your advice on materials is very helpful. I follow your point about engine size. I'll have a look at the designs you mention.The one that I was looking at has quite a long stroke at 2 x bore and I thought that, at that, it might be something of a "plodder" and not too temperamental. Perhaps more after the "Mills" engines of my youth. As an aside, the builder refers to filing the exterior of the crankcase to shape and cold chiselling the transfer passages, touch of the traditional LBSC methods there I thought!.

I already knew of your excellent notes on lapping in MEM. I'll look for the build notes that you mention.

Clive

As a youth I had very little luck starting either a DC Super Merlin quickstart or an AM15.  Tug recommended I try making a Dyno from Ron Chernich's drawings in the Motor Boys Plan Book  **LINK**

Video below

Edited By Roderick Jenkins on 23/11/2022 17:45:33

Yes, a good idea there Rod I'd forgotten your build on that - another good candidate for a subject.

Clive might also be interested in perusing this over in similar vein on HMEM ML Midge and these are links to my builds on MEM

The Atomatic, Oliver Tigres ETA 15s and the ED Hunter. All 5cc in size but I'm sure anyone wanting to build a small diesel will get something from all of them on something.

Fuel is always a problem these days but it is available from Leeds model shop though the price might be a surprise.

Gone are the days when all model shops stocked it - in half and one pint tins, 3/6d and 4/9d if memory of my first cans serves correct.

Best - Tug

Brings back memories of my EDB 1cc,which I never managed to start, although the chaps at the flying club could start it very easily. Recommended fuel was aqual parts of ether, diesel and Redex. Boots would sell ether to teenagers back then.