Ed Huntress wrote:
"Nick Müller" wrote in message
...

Ed Huntress wrote:


Do you have any experience building diesels?

No. But this is another story: My next project is a big stationary
Diesel engine that is located in Passau (somewhere between Munich and
Salzburg; to give you some reference). It was built 1906. Rudolf Diesel
personaly adjusted it. When I was there to have a first look at, I also
took the chance to visit the local second hand book seller*). And there
I found a book (1936 IIRC) about diesel engines that convinced me, that
it could be possible to build ones with say about 100 ccm. I didn't try
it yet, but sure sometime. Not with my current project.
I didn't decide on the scale yet, so don't know about the ccm's I will
have.
The problem is the injection pump (you guessed it), not the jet. To make
the engine running in idle you have to inject 0,5mm^3 for every 100ccm.
Well, that ain't really much.
I have seen someone who has built a real diesel with just a few ccm (I
guess less than 10) who claims to have an injection pressure of 80 atm.
Unfortunately I'm unable to contact him anymore and to squeeze him out.


This is a question that's interested me for some time: how small can you
make a diesel, one that runs on real diesel fuel (cetane +/- 45)?

I asked the question here before, and the consensus was that the smallest
*commercial* diesels were around 300 - 400 cc per cylinder. I didn't check
that out because it was far larger than I was interested in, so I suppose
the model making community is the place to ask.

There are, as I'm sure you know, some very small model diesels that run on
ether (ether/castor oil mixes for the 2-strokes). Someone in Pennsylvania
makes such a kit for home machinists.

But the cetane rating of ether is around 85 - 90, so it's not a good basis
on which to judge how one would run on conventional diesel fuel. Biodiesel
has trouble reaching a cetane rating of 40, so that's probably out.

Do you have any other ideas? I'm thinking of something around 100 cc.

--
Ed Huntress


I've made and burned a bit of biodiesel, Ed, and its cetane runs quite a
bit higher than 40. Here's a quote from one of the abstracts on the
biodiesel.org's site:

"A typical cetane number range for #2 diesel fuel is 40-45 while #1
diesel is 48-52.
Biodiesel from vegetable oils have been recorded as having a cetane
number range of 46
to 52, and animal fat based biodiesels cetane numbers range from 56 to 60."

Run your model diesel on processed bacon grease.

Dale Scroggins