Hi All!
Probably everyone here knows the excellent small hot bulb and diesel engines from Find Hansen.
I've already built several IC engines, but all of them running with regular gas and electronic ignition. Actually I don't like electronic ignitions as a battery is always required, and sometimes when I want to run my engines I end up with a empty battery and no fun.
I also made some experiments with piezo ignitions from lighters. They work ok, but are sensitive and usually fail after some few hours of operation.
Of course we all can easily build model diesel engines with regular carbs, running on diethylether fuel, but I don't like the smell of that stuff.
So here my next go to build a real diesel or hot bulb engine running on regular diesel fuel without any electronic components, similar to Find Hansens Engines and of course I want to share my experience.
I already tried to build a 2-stroke hot bulb engine with 30 cc displacement, but totally failed to get a good spray from the injector with such small diesel amounts and it ended up to be a 2-stroke gasoline engine with electronic ignition.
My new project is somehow based on a hit&miss engine I build 2 years ago. It will have a stroke of 60 mm and bore of 46 mm, which makes 100 cc displacement. I thought that a larger diesel engine should be easier to build than a small one.
I got a cast iron base, 2 large flywheels (30 cm diameter, 10 kg each), and some raw bearing supports:
The rest of the engine is my own design. I already started last winter, but production stalled in summer as I prefer to be outside then
I started of to build the crankshaft. I usually make them from several pieces. I use 2 steel blanks for the crank webs, weld them together on several small spots and drill the holes for the crank pin and crankshaft in one setup so they are exactly parallel.
After that I machined the crank shaft and crank pin, separated the two crank webs and put everything together with some loctite just to hold everything in place. I now cross drilled the crank webs and put dowel pins through both crankshaft and crank pin like this:
I now machined the crank webs to their final size and sawed out the piece of crankshaft between the 2 crank webs. Using this method I already prouced many good crank shafts, this one has a run out of less than 0,02 mm from end to end, which is acceptable I think.
I continued to machine the bearing supports, the base and the cylinder angle bracket. The crankshaft runs in cast iron bushings and with good lubrication I think this should run fine. After everything was machined a test fittet everything and was happy that the crankshaft with the flywheels turns smoothly.
Next I machined the cylinder out of some junk metal with a steel liner. The liner will be watercooled.
I continued with the cylinder head which is also made from a junk steel blank. I pressed in bronze valve cages. I made the valves from a piece of drill rod and silver soldered a bronze head onto it. With bronze valve cages and bronze valve heads you will never have any corrosion issues due to moisture or something.
I continued with the connecting rod, which I also make from several parts. First I made a cast iron blank for the big end bearing and drilled all holes and threads for the bearing cap. I basically made the same for the piston pin side. Both bearing blanks were now connected with a piece of steel bar. The steel bar has threads on both sides and threads into the big end and piston pin bearing. The thread is very tight and additionally secured with some loctite. Finally, I drilled the piston pin and crankshaft bearing in one setup so everythin is parallel again.
I was planning to make my own piston and rings, but found a 46 mm piston with rings and pin from an old motorcylce in my shop. As I had no other use for this piston, I decided to use it in this engine.
After putting everything together, I was happy that still everything turned nice and free.
Next, I machined another plate which holds the rocker arms and wich has a cooling water channel at the bottom side, so the cylinder head is sufficiently cooled. I made the rocker arms from some flat steel. The camshaft runs just below the cylinder head and will be driven by a roller chain. I milled the cams similar to some I made for earlier engines. A third cam will drive the injection pump. Currently, the cams are loose on the camshaft, as I need to have the roller chain first to correctly set the valve timing. After that, I temporarly fix the cams with some loctite, then cross drill them and ad a pin.
That's the state of the art right now. The next work will be the correct valve timing, cam for the injection pump, injection pump and injector and A hot bulb. I deciced to build a hot bulb engine, as it requires lower compression and should be better for a first go. Hot bulb engines also don't need a perfectly atomized fuel and the injection timing can be set to whatever timing and the engine should run. I want to try an injection at 180° before TDC, so the diesel fuel has enough time to evapourate.
Of course, I also need a centrifugal governor which controlls the amount of injected fuel.
I'll keep you updated, as soon as I have some more parts finished.
best regards,
Alex
Probably everyone here knows the excellent small hot bulb and diesel engines from Find Hansen.
I've already built several IC engines, but all of them running with regular gas and electronic ignition. Actually I don't like electronic ignitions as a battery is always required, and sometimes when I want to run my engines I end up with a empty battery and no fun.
I also made some experiments with piezo ignitions from lighters. They work ok, but are sensitive and usually fail after some few hours of operation.
Of course we all can easily build model diesel engines with regular carbs, running on diethylether fuel, but I don't like the smell of that stuff.
So here my next go to build a real diesel or hot bulb engine running on regular diesel fuel without any electronic components, similar to Find Hansens Engines and of course I want to share my experience.
I already tried to build a 2-stroke hot bulb engine with 30 cc displacement, but totally failed to get a good spray from the injector with such small diesel amounts and it ended up to be a 2-stroke gasoline engine with electronic ignition.
My new project is somehow based on a hit&miss engine I build 2 years ago. It will have a stroke of 60 mm and bore of 46 mm, which makes 100 cc displacement. I thought that a larger diesel engine should be easier to build than a small one.
I got a cast iron base, 2 large flywheels (30 cm diameter, 10 kg each
), and some raw bearing supports:
The rest of the engine is my own design. I already started last winter, but production stalled in summer as I prefer to be outside then
I started of to build the crankshaft. I usually make them from several pieces. I use 2 steel blanks for the crank webs, weld them together on several small spots and drill the holes for the crank pin and crankshaft in one setup so they are exactly parallel.
After that I machined the crank shaft and crank pin, separated the two crank webs and put everything together with some loctite just to hold everything in place. I now cross drilled the crank webs and put dowel pins through both crankshaft and crank pin like this:
I now machined the crank webs to their final size and sawed out the piece of crankshaft between the 2 crank webs. Using this method I already prouced many good crank shafts, this one has a run out of less than 0,02 mm from end to end, which is acceptable I think.
I continued to machine the bearing supports, the base and the cylinder angle bracket. The crankshaft runs in cast iron bushings and with good lubrication I think this should run fine. After everything was machined a test fittet everything and was happy that the crankshaft with the flywheels turns smoothly.
Next I machined the cylinder out of some junk metal with a steel liner. The liner will be watercooled.
I continued with the cylinder head which is also made from a junk steel blank. I pressed in bronze valve cages. I made the valves from a piece of drill rod and silver soldered a bronze head onto it. With bronze valve cages and bronze valve heads you will never have any corrosion issues due to moisture or something.
I continued with the connecting rod, which I also make from several parts. First I made a cast iron blank for the big end bearing and drilled all holes and threads for the bearing cap. I basically made the same for the piston pin side. Both bearing blanks were now connected with a piece of steel bar. The steel bar has threads on both sides and threads into the big end and piston pin bearing. The thread is very tight and additionally secured with some loctite. Finally, I drilled the piston pin and crankshaft bearing in one setup so everythin is parallel again.
I was planning to make my own piston and rings, but found a 46 mm piston with rings and pin from an old motorcylce in my shop. As I had no other use for this piston, I decided to use it in this engine.
After putting everything together, I was happy that still everything turned nice and free.
Next, I machined another plate which holds the rocker arms and wich has a cooling water channel at the bottom side, so the cylinder head is sufficiently cooled. I made the rocker arms from some flat steel. The camshaft runs just below the cylinder head and will be driven by a roller chain. I milled the cams similar to some I made for earlier engines. A third cam will drive the injection pump. Currently, the cams are loose on the camshaft, as I need to have the roller chain first to correctly set the valve timing. After that, I temporarly fix the cams with some loctite, then cross drill them and ad a pin.
That's the state of the art right now. The next work will be the correct valve timing, cam for the injection pump, injection pump and injector and A hot bulb. I deciced to build a hot bulb engine, as it requires lower compression and should be better for a first go. Hot bulb engines also don't need a perfectly atomized fuel and the injection timing can be set to whatever timing and the engine should run. I want to try an injection at 180° before TDC, so the diesel fuel has enough time to evapourate.
Of course, I also need a centrifugal governor which controlls the amount of injected fuel.
I'll keep you updated, as soon as I have some more parts finished.
best regards,
Alex
