Injected Diesel 56cc 2 Stroke, Will it ever work?"

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Pump diesel will not be a problem, many common rail engines circulate the fuel through the injectors. Plant oil based fuels can be a problem as they break down at high temperatures. Using cooking oil as a fuel for a conventional jerk pump system is ok, for common rail expect problems.
 
Hi Lloyd,

I was recently reading about old "Field Marshall" tractors, and I think they might be of interest as a source of ideas for your project. They use a single cylinder 2 stroke diesel, scavenged by crankcase compression like your engine will be.

First point regarding lubrication, they use oil fed to the bearings by a pump and drillings rather like a 4 stroke. A non return valve placed at the bottom of the crankcase allows excess oil to be forced out by crankcase compression and returned to the tank. If you used that strategy you wouldn't need to worry about seals on the big end.

Second point regards starting. They have a 'glow plug' in the form of a holder for a piece of smouldering paper that is screwed into the cylinder head. I think this would be a good system for our models, no need for electric heaters. Apparently the original paper for this purpose was soaked in potassium nitrate and would smoulder even in the absence of air, but modern owners say a piece of egg carton works just as well.

American readers may also be pleased to hear that the starting system on these tractors involves a blank shotgun shell... the shell is placed into a breech mounted to the cylinder and the engine rotated just past tdc. Then the firing pin is struck with a hammer. The ensuing explosion is directed into the cylinder where it kicks the engine over. I'm not sure if this system could be replicated on a model scale. Perhaps one could use a Ramset cartridge as the shell?
 
The Ruston-Hornsby single cylinder diesel in the grain elevator my father managed had the same paper glow plug, from memory, it was a tightly wrapped cylinder of paper about 1/4 to 5/16(6-8mm) in diameter x about 2.5 inches(63mm) long and was fitted in a plug that was drilled on the piston end for the 'glow plug' and screwed into the head.
 
For a model, has anyone ever used a gas lighter filling valve and a shot of butane gas to turn over an engine? With a glow plug it could ignite and give a suitable kick to start the engine?
I guess a 56 cc diesel really wants a decent starting handle or rope starter? A bicycle crank (6in?) is about the right size I guess?
The last car I had with a starting handle was a 2l, 4 cylinder petrol Volvo with fuel injection. 500cc per cylinder, 10.5:1 compression. C 1972. Of course, I have had many different motorcycles with kick-starters.
K2
 
For a model, has anyone ever used a gas lighter filling valve and a shot of butane gas to turn over an engine? With a glow plug it could ignite and give a suitable kick to start the engine?
I guess a 56 cc diesel really wants a decent starting handle or rope starter? A bicycle crank (6in?) is about the right size I guess?
The last car I had with a starting handle was a 2l, 4 cylinder petrol Volvo with fuel injection. 500cc per cylinder, 10.5:1 compression. C 1972. Of course, I have had many different motorcycles with kick-starters.
K2
For mine I was planning to rope start.
 
I would suggest that you look at a suitable drive dog or free wheel so you can turn it over with an electric drill, especially in the early stages. This allows you to adjust settings whilst the engine is turning.
 
Hi Lloyd,

I was recently reading about old "Field Marshall" tractors, and I think they might be of interest as a source of ideas for your project. They use a single cylinder 2 stroke diesel, scavenged by crankcase compression like your engine will be.

First point regarding lubrication, they use oil fed to the bearings by a pump and drillings rather like a 4 stroke. A non return valve placed at the bottom of the crankcase allows excess oil to be forced out by crankcase compression and returned to the tank. If you used that strategy you wouldn't need to worry about seals on the big end.

Second point regards starting. They have a 'glow plug' in the form of a holder for a piece of smouldering paper that is screwed into the cylinder head. I think this would be a good system for our models, no need for electric heaters. Apparently the original paper for this purpose was soaked in potassium nitrate and would smoulder even in the absence of air, but modern owners say a piece of egg carton works just as well.

American readers may also be pleased to hear that the starting system on these tractors involves a blank shotgun shell... the shell is placed into a breech mounted to the cylinder and the engine rotated just past tdc. Then the firing pin is struck with a hammer. The ensuing explosion is directed into the cylinder where it kicks the engine over. I'm not sure if this system could be replicated on a model scale. Perhaps one could use a Ramset cartridge as the shell?
Thanks for the ideas, N1000. I am temporarily stalled on the project due to other obligations, but it is still sitting on it reserved workbench in the middle of the shop.

Actually, this model will have a roots blower, which is one of the few parts that is actually finished and working obediently. Post #99 of this thread shows it in operation filling up a 130 liter plastic trash bag. So, there will be no combustion air passing through the crank case.

You aren't trying to get me in trouble suggesting those ramset blanks for a starting trick, are you? Like using ether and a match for re-seating the bead of a tire on a rim? That process never worked for me, and a little scary, too.
A high torque battery powered drill and a little over-running clutch might be easier on the heart (mine). I have had my share of uh-ohs where it took me a minute before I got the courage to look at my hand. Luckily, the only bad one was at age 15, and it was just my pinky. Didn't need it anyway, LOL. But at my age now, all parts that are still working are too valuable to risk too much.

I was wondering about the possibility of using a 2 stroke engine glow plug. I have a couple of them and they have a 1/4-32 thread an I can squeeze it into the head. But I am not sure if they will stay incandescent (a bad thing??) after the engine is running. Don't they rely on methanol or nitro to stay glowing? Just wondering if they will cool down after the voltage is remove from them. Or maybe it doesn't matter, but it does sound a little bit like cheating. Or maybe its just using technology to your advantage??

Lloyd
 
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Thanks for the ideas, N1000. I am temporarily stalled on the project due to other obligations, but it is still sitting on it reserved workbench in the middle of the shop.

Actually, this model will have a roots blower, which is one of the few parts that is actually finished and working obediently. Post #99 of this thread shows it in operation filling up a 130 liter plastic trash bag. So, there will be no combustion air passing through the crank case.

You aren't trying to get me in trouble suggesting those ramset blanks for a starting trick, are you? Like using ether and a match for re-seating the bead of a tire on a rim? That process never worked for me, and a little scary, too.
A high torque battery powered drill and a little over-running clutch might be easier on the heart (mine). I have had my share of uh-ohs where it took me a minute before I got the courage to look at my hand. Luckily, the only bad one was at age 15, and it was just my pinky. Didn't need it anyway, LOL. But at my age now, all parts that are still working are too valuable to risk too much.

I was wondering about the possibility of using a 2 stroke engine glow plug. I have a couple of them and they have a 1/4-32 thread an I can squeeze it into the head. But I am not sure if they will stay incandescent (a bad thing??) after the engine is running. Don't they rely on methanol or nitro to stay glowing? Just wondering if they will cool down after the voltage is remove from them. Or maybe it doesn't matter, but it does sound a little bit like cheating. Or maybe its just using technology to your advantage??

Lloyd
I think it is the methanol that keeps them glowing in glow motors. There are some special glow plugs made for running glow motors on petrol, though I don't know how they differ. Not cheating to use one in my opinion, you are just finding a engineering solution that works!

I wasn't being serious about the ramset starter, way too risky and there's no advantage over an electric start with a drill anyway. I just found the concept of starting your engine with an explosive charge amusing.
 
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I wasn't being serious about the ramset starter, way too risky and there's no advantage over an electric start with a drill anyway. I just found the concept of starting your engine with an explosive charge amusing.
Well, I am glad you didn't present that starting method as a dare, LOL.
 
Hi Lloyd,
snip

American readers may also be pleased to hear that the starting system on these tractors involves a blank shotgun shell... the shell is placed into a breech mounted to the cylinder and the engine rotated just past tdc. Then the firing pin is struck with a hammer. The ensuing explosion is directed into the cylinder where it kicks the engine over. I'm not sure if this system could be replicated on a model scale. Perhaps one could use a Ramset cartridge as the shell?

We had one of those tractors. IIRC it was an unusually sized shell - - - 10 ga - - - but then that is from information some over 50 years ago and no way to corroborate it today. (source is dead for some 11 years already)
 
Off of dead center
I am finally off of dead center on this project and have a top end, including a unit injector working like I think it should. There are a half dozen injectors in the scrap box, but this one, with its synchronized low pressure pump seems pretty close. I had to turn the fuel volume up way too high to get a cloud that was easy to see for the video. There is an electric motor powering the cam shaft. All rocker tips are rollers. Only the injector lifter is a roller lifter, because the loading is quite significant. The 1/4" dia black plastic handle at the top is just an extension of the fuel control lever that twists the helical plunger. It will eventually be controlled by a governor.... I think.


 
PISTON
Now that I am past the injection (an almost fatal consumer of good shop time), I can have fun again. I made the piston last night, but it still needs ring grooves, after I have the rings. There are lots of 39mm rings available, and after the injector debacle, I will be buying the rings.

This is a two cycle engine of 39mm bore and 50.8mm stroke so the piston has to be very tall to seal the inlet ports when at TDC. Also, the wrist pin hole has to be very low in the piston so that the rod has clearance to the cylinder walls when the rod is at its most extreme angles. That also means a very long conn rod and the resulting balance problems.

But I am getting back into the fun.
I did have a near disaster when making the piston. I was using an internal 3 jaw to hold the piston inside the skirt to take the final clean-up cuts on the piston O.D. And of course, with the long cantilever, the tool grabbed and yanked the piston off the jaws. I was afraid to dig the piston out of the chip pan, but luckily, there was just enough cleanup material left to fix the boo-boo. One of the rings will have to be positioned over the one gouge that was a bit too deep.

Thinking back on this, many of the mishaps where I do, or almost do, ruin a part, are because of inadequate fixturing. Hmmmmm.

Piston-1.png
 
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