Diesel engine : Kromhout Gardner 4LW 1940

[Lloyd-ss]

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.


View attachment 149187

Hmmmm. That is an interesting solution. Letting the large spring drive the piston and control the maximum pressure, too. No matter what, It seems that getting the spring forces correct is always difficult and requires trial and error and often winding a spring by hand. Having a supply of various diameter check balls and very light springs could be helpful.

Minh Thanh's pump could incorporate a similar scheme by breaking the single long pressure piston into 2 shorter pistons with a spring in between the two pieces to maintain continuous force on the fuel and to also limit the max pressure. Again, finding the correct springs by experimentation would be time consuming. Minh's solution does show an easy adjustment for the pressure relief valve.

Many solutions to the same problem/pump.

 

[minh-thanh]

I also intend to replace the ball valve with a leaf valve, because the pump only needs to create a small pressure, the pump parts do not need to be too complicated to machine

 

[Mechanicboy]

Hmmmm. That is an interesting solution. Letting the large spring drive the piston and control the maximum pressure, too. No matter what, It seems that getting the spring forces correct is always difficult and requires trial and error and often winding a spring by hand. Having a supply of various diameter check balls and very light springs could be helpful.

You will find this same mode of operation as in the feed pump for diesel pumps and petrol pumps in petrol engines. pump diameter must be larger so it ensures that there is a little overpressure present as long as it is consumed by the engine. pumps less at idle and pumps more at increasing revs. spring force does not need to be so powerful that it delivers enough fuel continuously before it is re-sucked by cam or eccentrics.

 

[minh-thanh]

About the auxiliary pump to increase the pressure of the fuel, I am thinking....
There is another solution: instead of lowering the self-ignition temperature of the fuel I would raise the temperature of the air before it enters the engine's cylinders. and as it is further compressed in the cylinder the temperature of the compressed air will increase further. Just raising the temperature of the air for a short time (about 5 to 10 seconds - I think) is enough
There are 2 methods: 1/using the heat from the torch and 2/using electricity and resistor wires
I am thinking about method 1 , if it is ok then I will think more with method 2

 

[Mechanicboy]

About the auxiliary pump to increase the pressure of the fuel, I am thinking....
There is another solution: instead of lowering the self-ignition temperature of the fuel I would raise the temperature of the air before it enters the engine's cylinders. and as it is further compressed in the cylinder the temperature of the compressed air will increase further. Just raising the temperature of the air for a short time (about 5 to 10 seconds - I think) is enough
There are 2 methods: 1/using the heat from the torch and 2/using electricity and resistor wires
I am thinking about method 1 , if it is ok then I will think more with method 2

You can use a glow spiralwire inside the pipe connected to the intake manifold to heat the air while starting the engine.

 

[Nerd1000]

You can use a glow spiralwire inside the pipe connected to the intake manifold to heat the air while starting the engine.

Full sized diesels have used many methods for this, most commonly an electric intake air heater (as on cummins 6BT) or glow plugs. But there are other more unusual methods, such as a diesel fuelled inlet heater (essentially a device that deliberately starts a fuel fire in the manifold prior to cranking), secondary petrol fuelled combustion chambers attached to the cylinder heads that allow the engine to warm up as a spark ignition engine, and the use of a 'pony motor' plumbed into the same coolant circuit as the main engine to both preheat the whole engine block and provide cranking (old CAT bulldozers did this).

I think the easiest starting method for us hobbyists is careful use of ether based starting fluid. Some old tractors actually had automatic ether dosing systems for cold starts. Using too much can of course lead to engine damage...

 

[Mechanicboy]

Full sized diesels have used many methods for this, most commonly an electric intake air heater (as on cummins 6BT) or glow plugs. But there are other more unusual methods, such as a diesel fuelled inlet heater (essentially a device that deliberately starts a fuel fire in the manifold prior to cranking), secondary petrol fuelled combustion chambers attached to the cylinder heads that allow the engine to warm up as a spark ignition engine, and the use of a 'pony motor' plumbed into the same coolant circuit as the main engine to both preheat the whole engine block and provide cranking (old CAT bulldozers did this).

I think the easiest starting method for us hobbyists is careful use of ether based starting fluid. Some old tractors actually had automatic ether dosing systems for cold starts. Using too much can of course lead to engine damage...

In the model diesel engine the heated air is better due ether isn't cheap and some countries are the ether not available for buyers. I'm car mechanic since 1993 and know how the diesel engine works. And I had repaired the tractor Massey Ferguson and John Deere where my relatives are farmers.

 

[minh-thanh]

You can use a glow spiralwire inside the pipe connected to the intake manifold to heat the air while starting the engine.

similar to mine , but i won't use it until i can get the damage under control , just it breaks and everything will be sucked into the cylinder . And there are many other issues...such as finding an insulator...as well as making sure the air absorbs heat in the best way....

 

[Mechanicboy]

similar to mine , but i won't use it until i can get the damage under control , just it breaks and everything will be sucked into the cylinder . And there are many other issues...such as finding an insulator...as well as making sure the air absorbs heat in the best way....

You can use metal mesh around the glow spiral so pieces do not get into the engine.

 

[Lloyd-ss]

Reading this last series of posts about ways to improve starting (I think that is the point of the current sidebar discussion) it seems like there is plenty of opportunity to be creative.

I ran across these 100 deg C Polyimide film heaters (cheap). These are 12v, 25mm x 50mm 7 watt. Might be a way to easily preheat the head.

 

[minh-thanh]

Reading this last series of posts about ways to improve starting (I think that is the point of the current sidebar discussion) it seems like there is plenty of opportunity to be creative.

I ran across these 100 deg C Polyimide film heaters (cheap). These are 12v, 25mm x 50mm 7 watt. Might be a way to easily preheat the head.

No, this is not a side discussion.
With my 1-cylinder engine it is relatively easy to warm up the head to run with diesel, but with this engine to warm the head for diesel oil is a problem, especially when tuning it. . So I'm thinking and figuring out how to fix it
The capacity of a cylinder is about 9 cc - and 36cc is the capacity of the engine so the area to install additional heaters for the head or inlet air is small. So it is necessary to find a way to heat it that must be compact and...beautiful ..
With a diesel engine, I don't care what fuel it's run on - but I like a little more simplicity in fuel use. and like i said : i will use this engine for testing , the experience gained i will use it in version 2 or other engines
PS :
I am making an inlet air heater
I only tested on one cylinder, if that cylinder is easier to start I will do more with the other cylinder.

 

[Lloyd-ss]

Maybe for a quick and dirty test just feed the air intake with a hair dryer or heat gun to see if it helps?

 

[minh-thanh]

PS :
I am making an inlet air heater
I only tested on one cylinder, if that cylinder is easier to start I will do more with the other cylinder.

Maybe for a quick and dirty test just feed the air intake with a hair dryer or heat gun to see if it helps?

I tried heating up the inlet air heater, but it couldn't get the air hot enough for the engine run, even though the engine felt like it wanted to self-ignite.
I would buy kerosene even though kerosene and diesel auto-ignition temperatures are about the same, but it seems like the engine is easier to run with kerosene

PS: The engine is really easy to run with a mixture of ether and diesel when the engine is at room temperature

 

[minh-thanh]

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

I went out for some work today, I bought a 150 mm can to increase the cetane number for diesel fuel. I hope it will improve the cold start of the engine. I will update more

 

[timo_gross]

Heater cartridges from 3d printers can heat up the aluminium of the engine, if you are able to accomodate a heater block or blind hole.
You get around 40 W out of one. Diameter 6mm and length 20 mm.
No idea if that is useful information, or if i miss the point. At least it is not very expensive (provided you have a power supply already).
Greetings.

 

[Steamchick]

DERV = Diesel Engine Road Vehicle fuel - contains 3 basic components. I don't know the chemical names, but when they mixed "laboratory standard DERV" in the chemistry Lab at work for testing other materials, they took a very large percentage of the correct diesel oil (A heavy paraffin oil?), A lubricant, some "starter" chemical (Aromatic?). (Not Ether, but another something that ignites at a lower temperature and initiates combustion before the base oil flashes...??. This is the stuff that is volatile but gives road fuel it's distinctive "sharp" smell. Compare year-old fuel from a plastic container with fresh fuel, for smell!). I don't really understand Cetane booster, but I found this on the web- "Diesel fuel that readily burns, or has good ignition quality, improves cold start performance. The cetane number of the fuel defines its ignition quality. It is believed that fuels meeting the ASTM D 975 Standard Specification for Diesel Fuel Oils minimum cetane number requirement of 40 provide adequate performance in modern diesel engines. The minimum cetane number in Europe is 51.". So that answers that one!
Also: "Fuel properties can affect combustion noise directly. " "By increasing the cetane number of the fuel, the knock intensity is decreased by the shortened ignition delay. Fuels with high cetane numbers ignite before most of the fuel is injected into the combustion chamber. The rates of heat release and pressure rise are then controlled primarily by the rate of injection and fuel-air mixing, and smoother engine operation results."
I understand that there are seasonal additives, e.g. a de-waxing additive that is used to make "Winter" and cold-climate fuel, and an additive to increase lubricity.... that helps preserve the longevity of the fuel pump and injectors. But these extra things are not always in "basic DERV", as the vary company by company and by season.
Look-up Wiki, etc. for more information. This interested me:
https://www.chevron.com/-/media/chevron/operations/documents/diesel-fuel-tech-review.pdfI watched a programme on TV where they tried Cooking oil replacement for diesel cars... A gallon of your regular supermarket oil, with a coffee cup of regular "turpentine substitute" paint thinners - to act as the "Starter aid". Apparently, cooking oil is only good on hot engines without the cup of "turps"...?
However, I was advised by an engine guy, that cooking oil makes a dirty engine - can produce gum that affects injectors, pump valves, etc. and leaves deposits inside the combustion chamber that you don't see with "proper DERV". The lubricity of vegetable oil may be low, and pump and injector wear can shorten the life of these components by half - or more (!). Do your on-line research first? (I may be wrong, - just what someone said...?).
K2

 

[grahamgollar]

If you look carefully at the full size Gardner engine you will find a 'cold start' button at the free end of the fuel pump which allows extra rack travel on start up. Even the original engines needed some encouragement to start!!
Despite that, an experienced operator could start an engine with a starting crank handle - not the usual 360degree gut wrenching technique but just a gentle back and forth rocking about TDC. I've seen this done on the much bigger 8LW engines.
Graham

 

[minh-thanh]

I went out for some work today, I bought a 150 mm can to increase the cetane number for diesel fuel. I hope it will improve the cold start of the engine. I will update more

Update: I've tried mixing it with diesel oil , although the engine does need to warm up a bit - about 12 seconds - easier to start the engine. That's enough for me . If necessary, I will mix it with a higher ratio .

Heater cartridges from 3d printers can heat up the aluminium of the engine, if you are able to accomodate a heater block or blind hole.
You get around 40 W out of one. Diameter 6mm and length 20 mm.
No idea if that is useful information, or if i miss the point. At least it is not very expensive (provided you have a power supply already).
Greetings.

View attachment 149247

I have looked at the information about it, there is a 12v - 40w type, the temperature is about 350 degrees Celsius, quite cheap, quite ideal for warming up the engine's cylinders. I'll buy one or two for testing... Maybe I'll add it in version 2 or in other designs. . Thank you . !

 

[Nerd1000]

DERV = Diesel Engine Road Vehicle fuel - contains 3 basic components. I don't know the chemical names, but when they mixed "laboratory standard DERV" in the chemistry Lab at work for testing other materials, they took a very large percentage of the correct diesel oil (A heavy paraffin oil?), A lubricant, some "starter" chemical (Aromatic?). (Not Ether, but another something that ignites at a lower temperature and initiates combustion before the base oil flashes...??. This is the stuff that is volatile but gives road fuel it's distinctive "sharp" smell. Compare year-old fuel from a plastic container with fresh fuel, for smell!). I don't really understand Cetane booster, but I found this on the web- "Diesel fuel that readily burns, or has good ignition quality, improves cold start performance. The cetane number of the fuel defines its ignition quality. It is believed that fuels meeting the ASTM D 975 Standard Specification for Diesel Fuel Oils minimum cetane number requirement of 40 provide adequate performance in modern diesel engines. The minimum cetane number in Europe is 51.". So that answers that one!
Also: "Fuel properties can affect combustion noise directly. " "By increasing the cetane number of the fuel, the knock intensity is decreased by the shortened ignition delay. Fuels with high cetane numbers ignite before most of the fuel is injected into the combustion chamber. The rates of heat release and pressure rise are then controlled primarily by the rate of injection and fuel-air mixing, and smoother engine operation results."
I understand that there are seasonal additives, e.g. a de-waxing additive that is used to make "Winter" and cold-climate fuel, and an additive to increase lubricity.... that helps preserve the longevity of the fuel pump and injectors. But these extra things are not always in "basic DERV", as the vary company by company and by season.
Look-up Wiki, etc. for more information. This interested me:
https://www.chevron.com/-/media/chevron/operations/documents/diesel-fuel-tech-review.pdfI watched a programme on TV where they tried Cooking oil replacement for diesel cars... A gallon of your regular supermarket oil, with a coffee cup of regular "turpentine substitute" paint thinners - to act as the "Starter aid". Apparently, cooking oil is only good on hot engines without the cup of "turps"...?
However, I was advised by an engine guy, that cooking oil makes a dirty engine - can produce gum that affects injectors, pump valves, etc. and leaves deposits inside the combustion chamber that you don't see with "proper DERV". The lubricity of vegetable oil may be low, and pump and injector wear can shorten the life of these components by half - or more (!). Do your on-line research first? (I may be wrong, - just what someone said...?).
K2

Cetane improver additive is often amyl nitrate (not to be confused with amyl nitrite, which is a medicine that is often abused for less legal activities) or octyl nitrate. These compounds are essentially milder (non explosive) relatives of nitroglycerin, so it's no surprise they speed up ignition of the fuel...

 

[Lloyd-ss]

Very interesting discussion on diesel fuel, and K2, thanks for the thoughts on the change of fuel properties when diesel fuel is stored for long periods of time. The USA highway diesel fuel I have (No. 2 diesel) has been stored for about a year and has changed color and smell. We also have kerosene, sold generally as No. 1 diesel. It seems like fresh fuel is always important (both gasoline and diesel), but the more I read, the more confused I got. Quite a complex subject. Also, the seasonal differences in highway diesel blends is always there.

This makes me think that, because home built diesels seem to be (generally) a bit difficult to start, that having a fuel with consistent properties from session to session, might be causing more problems than one would expect.
Just a thought.