Diesel engine : Kromhout Gardner 4LW 1940

[minh-thanh]

Kerosene is easy to atomize than diesel oil due difference of the viscosity in kerosene and diesel oil. The gasoline engine can run on kerosene but not so easy to use diesel oil in gasoline engine.

Yes I know kerosene is easier to "atomize", But still make sure the compressed air inside the cylinder has to reach the temperature limit where the injected fuel has to self-ignite.

What compression ratio did you end up using for this engine? I think original gardener diesels were something like 15:1 which is probably too low for a model scale with greater heat losses relative to the mass of air in the cylinder.

I increased the compression ratio to 20-1, as you can see my engine loses heat very easily - especially at the cylinder head , which makes tuning and testing very difficult.

Find Hansen used compression ratio 20:1 and kerosene with 2% oil to lubricate the injection pump.

For the fuel - kerosene - to self-ignite, the temperature of the compressed air in the cylinder must reach a limit of about 200 degrees Celsius. That makes me feel strange and confused...with the system and the fuel he uses !!!?? Because the temperature of 200 degrees Celsius of air is compressed in the cylinder it is not a small number and is not easily achieved.

 

[Lloyd-ss]

Would a Cetane booster additive from the auto supply store be helpful?

 

[minh-thanh]

Would a Cetane booster additive from the auto supply store be helpful?

Yes , that could be a solution .
Thank you!
I am also thinking and looking for a solution to prevent the vaporization of volatile and low temperature fuels in the pump system. , because I need the engine running before I can make further adjustments

 

[Roger B]

20-1 compression ratio will work with a compact combustion chamber with minimal heat loss. My diesel has, I think, a higher ratio. The compression pressure is around 30-35 bar when cranked at 2000 rpm with the drill.

For volatile fuels you will need a feed pump for the injection pump. For petrol (gasolene) a pressure of around 0.8 bar (10 psi) is required. This is used on full size engines with mechanical fuel injection.

 

[minh-thanh]

My diesel has, I think, a higher ratio. The compression pressure is around 30-35 bar when cranked at 2000 rpm with the drill.

A question that I was going to ask you a long time ago but forgot, Do you just install the pressure gauge directly on the head Cyl of the engine / the fuel pump ??

For volatile fuels you will need a feed pump for the injection pump. For petrol (gasolene) a pressure of around 0.8 bar (10 psi) is required. This is used on full size engines with mechanical fuel injection.

This is probably the right solution and I'm thinking about it too.
Thank you !

 

[minh-thanh]

For those who need more information !

 

[Lloyd-ss]

I finally gave up on trying to rely on a gravity feed to my unit injector and added a simple pump with 2 ball checks. Driven off the cam shaft. I ended up putting a bushing in the pump cyl because it was pumping way too much fuel and a lot of agitation from the return line from the injector. I have no idea what pressure it puts out. I used an o-ring on the little piston rod rather than fight to get a leak-proof fit metal-to-metal piston fit.

 

[Lloyd-ss]

Minh-Thanh,
Also take a look at Cetane ratings, which is quite important also, maybe more important, especially for fuel blends.

edit- added this- But I haven't actually tried to get mine running yet, so you can just ignore what i say, LOL.

 

[minh-thanh]

edit- added this- But I haven't actually tried to get mine running yet, so you can just ignore what i say, LOL.

That's a pretty cool pump
I'm planning to use a worse pump than yours ----hope it will be ok with the oil -,Adjust the pressure by varying the voltage to the motor

 

[Lloyd-ss]

Are glow plugs an option for model diesels? Just curious.

 

[minh-thanh]

Are glow plugs an option for model diesels? Just curious.

I tried glow plugs on a single cylinder engine, but it was too short to reach the combustion chamber


Hi All !
A short video when the engine runs, no water cooling system
There's still a lot of tweaking to do, but when the engine runs it tells me everything is fine and going as planned
The fuel pump system and injectors are fine, the most important thing is still the ability of the crankshaft
This engine has a lot of things that I am not satisfied with so I will use the engine to test ....and the results and experience I will apply it in the new version

 

[Roger B]

Excellent

 

[Roger B]

A question that I was going to ask you a long time ago but forgot, Do you just install the pressure gauge directly on the head Cyl of the engine / the fuel pump ??



This is probably the right solution and I'm thinking about it too.
Thank you !

My compression gauge fits in place of the injector. It has a non-return valve as close to where the injector nozzle would be as possible so as not to affect the combustion chamber volume. The valve currently doesn’t seal as well as I would like.

In the video clip the pressure is reaching more than 40 bar but there was no clearance between the valves and the piston. I have since added a 0.5mm copper shim gasket which has reduced the pressure to 30-35 bar which is still sufficient for a cold start.

I have used two different types of fuel feed pump. One is a diaphragm pump based on full size practice where the pressure is maintained by a spring.

The other is an electric pump like you are thinking of using with a pressure relief valve mounted on the injection pump to allow the fuel to circulate. The pump is rated for 12V and delivers more than enough fuel with a 5V supply.

 

[Basil]

I tried glow plugs on a single cylinder engine, but it was too short to reach the combustion chamber


Hi All !
A short video when the engine runs, no water cooling system
There's still a lot of tweaking to do, but when the engine runs it tells me everything is fine and going as planned
The fuel pump system and injectors are fine, the most important thing is still the ability of the crankshaft
This engine has a lot of things that I am not satisfied with so I will use the engine to test ....and the results and experience I will apply it in the new version

Thank you for sharing the build. That's quite an achievement.

 

[minh-thanh]

Hi @Roger B !
Thank you for the pictures and information !
One more question, is that also how you measure the pressure of the fuel pump? I am planning to make a gauge like yours to measure and check the pressure of the cylinder and the fuel pump . I'm also looking for a way to measure the average fuel per injection...I need a relative number for all, that's part of the reason I made this engine, 4 cylinders and 4 pumps. I will have a pretty accurate number

 

[kuhncw]

Minh,

It's good to see your diesel run in the video. Building a multicylnder model diesel of your own design is a great accomplishment.
Congratulations and keep up the good work.

Chuck

 

[Lloyd-ss]

Minh-thanh,
I have seen some folks collect the atomized fuel, but I have instead used a gravity feed to the pump from a clear skinny plastic container with some markings on it. If you know the rpm you can figure the injector strokes and the total volume used. It can work.
+++++++++
And of course, congrats on the successful building and running of the 4 cylinder diesel engine.
I wonder how many model engine builders in the world have achieved that in a 4 cylinder!?
Lloyd

 

[minh-thanh]

Minh-thanh,
I have seen some folks collect the atomized fuel, but I have instead used a gravity feed to the pump from a clear skinny plastic container with some markings on it. If you know the rpm you can figure the injector strokes and the total volume used. It can work.
+++++++++

Lloyd

I think that would be the best way to measure the fuel for my engine. Instead of measuring the amount of fuel at the outlet which depends on quite a few factors, I can measure the amount of fuel at the inlet. A great solution
Thank you !
--------------

Hi .
Thanks for the compliments, encouragement and likes !
Thank you so much .

 

[minh-thanh]

Hi All !

With the pump I was going to use, I tried it pumping some diesel and left it overnight and the rubber valves started to fail in the oil, so I'm going to make a pump.
My two ideas for a fuel "booster" pump system
The pump camshaft will have 2 lobe , it will help maintain a more stable pump pressure - just my thoughts - , it can be assembled on crankshaft or camshaft , but for this engine I will use it with the motor electricity
It only has the function of maintaining a small pressure, so it probably doesn't need it to be too sealed

 

[Mechanicboy]

Here is the better solution. The spring is pumping the fuel into the injection pump, if pressure is enough then the spring is feeding the fuel before the cam is pushing the lever to suck more fuel. The spring is maintained to keep the continuous fuel feeding. The pump piston diameter must be large enough, but not to inject the fuel into the combustion chamber, injection pump only.