Engine Almost Done Off To NAMESThe engine was completed to this point so I could take it NAMES. The plumbing is not yet complete. I finished it 3pm on Wed and left the next day for NAMES. I had run it once unpainted with an alcohol burner for about 20 minutes just to make sure it would work. I ran it for about 10 min after it was ready to go again just before packing it up to make sure it would at least start and go. So the NAMES show was the first trial runs. In keeping with my original objective on page 1 of the thread of sharing everything ie mistakes, success, and not so success this post gives an overview of how well all my modifications came out during its first outing.
The key testing for me was the burner operation and how well the heat was contained and focused onto the Displacer end cap which I made of copper. Secondary testing was pump operation, linkages, piston sealing as I used graphite string, and that nothing worked its way loose. Unfortunately I got so caught up in running the engine I forgot to shoot a video at NAMES, actually I only took one picture of my setup!
Heat System ResultsThe regulator was purchased at
http://contenti.com/gentec-preset-tank-regulators. It says preset but I was able to adjust it. I will be experimenting more with it and will be reporting later. My gauge only read from about 2# to 30#. The burner worked effectively from the 2# all the way to 15# before it started to jump off the ceramic. At startup I took it up to 15# and it would take off in about 90 seconds. I then turned it way down. It ran nice and smooth at the 2 - 3 # range. I need a gauge that reads to tenths of a pound in order to see just how well the regulator works. Brad Smith lent me his regulator with a tenths reading gauge. He runs his at about .2# pressure. Using his regulator setup the engine ran nice at .8 to .9# pressure. When I used his gauge is when I discovered that I had not set up the orifice as he did. Brad did not understand why I had to restrict the air flow around the inlet. He runs his wide open mine is almost 95% closed. As you may recall from the burner post I used a cutoff burner torch for my burner feed parts and made the burner small ie .700 diameter. When I made my burner I misunderstood Brad when he told me to drill through or remove the screen. I thought he meant the burner guts at the top and not the orifice. So my burner used the propane orifice as it came with the torch - no modifications. I also insulated my furnace with .06 asbestos sheet on its walls (see pictures posted earlier) and the gasket between the engine base and the displacer cylinder was of the same material. The asbestos sheet extended beyond the displacer flange to cover the top of the furnace. My entire objective was to keep the heat in the furnace not on the upper part of the engine. To that end the bottom of my Stainless Steel Displacer Cylinder is capped with copper not Stainless. The heat needs to go into the cylinder not up to the base. This method was suggested by Brad Smith.
The bottom line is the engine ran nice and slow - about 80 to 100 RPM by my watch. It ran the whole day and you could put your hand at the base of the cylinder and just leave it there to there was very little heat transferring up from the furnace. The water never got hot just very slightly warm if anything, I did not have a thermometer to test it. You could put your finger on the furnace and it would not burn you but it was hot, you could leave it there for a bit.
Next Heat System ExperimentsMy next steps are to change out the orifice. I have the one from McMaster Karr with a .010 orifice. I need to figure out an adaptor to put it in the current unit. Next I will take another orifice from another burner and drill out the hole to the #80 and try it. I am also going to get a gauge that reads to tenths - ie a 10#. I should then be able to test out the regulator as well as the different orifices.
The Burner post on page 11 has a PDF with design info on the burner as well as Sandy’s drawings.
Rest of Engine ResultsAs noted above the engine ran just fine. There were no loose bolts , no squeaking or binding I could sense. The piston stayed sealed fine. There is some play in the crank bolt the two links connected to it move a bit. It seems to make definite clank you can hear in the video. If I put my finger on the two links 80% of the clank goes away. I will make a new Crank bolt to see if I can eliminate it or maybe just try some shims. I used silicone oil in the cylinder and down the Displacer piston rod. I used this so there would be no carbon build up of burnt oil at the bottom of the Displacer Cylinder. This would of course reduce heat transfer. I was told I could use Mobil 1 or Marvel Mystery Oil and get the same results. I will likely change. I used 5W hydraulic oil on all the bearings. Given they are oilite I was just trying to get them a bit recharged.
Next Engine Build StepsI need to make the air hammers, stack top, and a tank, along with associated final plumbing. I am going to work on these first as the heating system I have does work for any display setup in the upcoming months.
Bob
Here is a video
