Diesel engine : Kromhout Gardner 4LW 1940

[Steamchick]

In industrial practice, given 8 variants of design, manufacture and materials, it is common practice to select "the one that works best", "best" being "longest without maintenance".
K2

 

[minh-thanh]

Yes .
With this engine I need to clarify a few of my questions about the fuel pump system, the fuel used and the injectors.
Up to this point, I understand more about the fuel used and fuel pump system
About the injectors I'm trying....

 

[Roger B]

Glad to hear you have got some runs from the engine

Shame about the missing bolts but that is a relatively easy fix.

I have been expermenting again with needle style injectors. They seem to run quite well but you always have the problem of fuel leaking past the needle. On one test run the needle jammed open and the engine kept running (although not so well) with just the 0.2mm nozzle. I may do some more experiments with open injectors, other than the very small hole they would be much simpler.

 

[xander janssen]

An open injector works similar as the "spray cup" in the Brons engine patent.

https://en.m.wikipedia.org/wiki/Brons

 

[minh-thanh]

Glad to hear you have got some runs from the engine

Shame about the missing bolts but that is a relatively easy fix.

I have been expermenting again with needle style injectors. They seem to run quite well but you always have the problem of fuel leaking past the needle. On one test run the needle jammed open and the engine kept running (although not so well) with just the 0.2mm nozzle. I may do some more experiments with open injectors, other than the very small hole they would be much simpler.

View attachment 149014

Yes, I have made injectors like yours before
Even though my engine was running with that injector, I had to make the pump cylinder bigger - 3mm, if I remember correctly - to compensate for the fuel lost through the injector body.
There is another problem: make sure the spring force creates enough compression for the needle - otherwise the pressure in the cylinder will blow all the fuel in the system out.

The design is old and wrong at the injector head, I corrected it when building the injector

 

[Roger B]

Here is a run with the needle injector:



The original Eisfeld model aircraft diesel engine used an open injector having also tried needle types. He then moved on to the current carbureted design. I have attached a translation of the original article.

 

[minh-thanh]

Roger !
What material do you use for the gasket of the cylinder head !??
I fixed the injectors, they seem better
But :

 

[Mechanicboy]

You can use soft copper or aluminium ring around the cylinder and the outside to water and oil canals use o- ring.

 

[Roger B]

I use an industrial pipe gasket material, VALQUA No.6500. It was available in small sheets for model RC car engine exhaust sealing. I am using a 1mm thickness.

https://www.valqua.com/product/sg6500/
I am sure there are many similar materials available.

 

[lee webster]

I bought an Isetta buble car once with a blown head gasket. Another owner suggested making a gasket from a thin sheet of aluminium that was then annealed to soften it. I didn't know what I was doing so I never got it to work. You might.

 

[minh-thanh]

Thanks for the comments !
I am thinking and looking for a solution to make head gasket, Because it is a high compression ratio engine, many cylinders and this is the first time I have trouble with it.
A project with many problems to solve

 

[Mechanicboy]

Thanks for the comments !
I am thinking and looking for a solution to make head gasket, Because it is a high compression ratio engine, many cylinders and this is the first time I have trouble with it.
A project with many problems to solve

In our Norwegian "Sabb" boat diesel engine has a round copper cylinder head gasket with 2 rubber gasket left and right side of the cylinder to lead coolant from cylinder to cylinder head. A inspiration for you?

 

[Roger B]

I have used that material on several engines without problems. The compression pressure on my 25mm bore four stroke diesel is around 40 bar and the cylinder head is fixed with 5 M4 studs.

 

[minh-thanh]

In our Norwegian "Sabb" boat diesel engine has a round copper cylinder head gasket with 2 rubber gasket left and right side of the cylinder to lead coolant from cylinder to cylinder head. A inspiration for you?

View attachment 149066

Your way is "hard" to use with design,....on my engine

 

[xander janssen]

I use a cellulose base with NBR rubber binder compound.

https://www.bengs-modellbau.de/material/dichtelemente/abil-dichtpapier
To avoid direct contact between the combustion gasses and reduce peak pressure load, I give the cylinder-head a raised middle section that has a tight slide fit into the cylinder liner. My single cylinder petrol engine even runs without the gasket although less good due to reduced compression.



I understand that this is more difficult in a multi cylinder engine as you then carefully have to control the diameter and position accuracy in order to make all 4 bosses to fit in the cylinder block.

 

[minh-thanh]

I bought an Isetta buble car once with a blown head gasket. Another owner suggested making a gasket from a thin sheet of aluminium that was then annealed to soften it. I didn't know what I was doing so I never got it to work. You might.

A little improvement and Gasket problem solved, engine has good compression and is fine with my many test runs of the engine !!

Hi All !
With the last test run, the engine could not start, I checked and found that the pump camshaft was rotated, it was no longer in the set position .
Everything is inside the engine so it's really hard to tune ...
Until now :
- The pump system is fine but needs a bit of improvement for the 2nd version or another engines
- The injector has been fine with many test runs
With this engine, from the beginning of the test run I use diesel, I will buy and use kerosene for the next time.
I will update when the engine runs that I feel fine

PS : I am designing 2 types of single cylinder diesel engine, I will use my experience with this engine in the new design.

 

[minh-thanh]

Hi All !
I have some work to do so I haven't returned to this project yet
Just a few thoughts:
The self-ignition temperature of kerosene and diesel is the same - about 210 degrees Celsius, how to maintain that temperature during tuning...? Because with this engine the heat loss is quite fast
Or should I change the pump system a bit to use a more self-igniting fuel ??

 

[Mechanicboy]

Hi All !
I have some work to do so I haven't returned to this project yet
Just a few thoughts:
The self-ignition temperature of kerosene and diesel is the same - about 210 degrees Celsius, how to maintain that temperature during tuning...? Because with this engine the heat loss is quite fast
Or should I change the pump system a bit to use a more self-igniting fuel ??

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.

 

[Nerd1000]

Hi All !
I have some work to do so I haven't returned to this project yet
Just a few thoughts:
The self-ignition temperature of kerosene and diesel is the same - about 210 degrees Celsius, how to maintain that temperature during tuning...? Because with this engine the heat loss is quite fast
Or should I change the pump system a bit to use a more self-igniting fuel ??

You might try heating the cooling water with a sous-vide heater or similar? That should keep the block temperature consistent.

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.

 

[Mechanicboy]

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