# Mini diesel engine.

### Help Support HMEM:

#### Mechanicboy

##### Well-Known Member
But modern engines use a common rail at 3 to 5 bar, with piezzo- electric injectors that boost injection pressure
K2
3 to 5 bar??? Not correct, common rail diesel engine has a maximum 1200-1500 bar. To start up the engine 200-250 bar and normal use can be varied between 300-500 bar depending on the brand of common rail diesel engine.

#### Mechanicboy

##### Well-Known Member
To find correct compression ratio to get high air temperature to ignite the fuel (kerosene autoignition approximately 295 degree celsius) then you need higher heat temperature who are more than 295 C, let us say 300-350 degree to start the engine without to heat up the cylinder head or use ether, then read here the link how to calculate and find the correct compression ratio if you want higher temperature than autoignition of the kerosene.. Or the other alternative instead calculate: Increase compression ratio with thickness of cylinder head gasket and try how easy the engine will start up.

Calculating heat of compression?

#### Mechanicboy

##### Well-Known Member
Found the compression calculator in this link Compression Ratio Calculator (Static and Dynamic)

Use syringe with 1 or 2 milliliter/cubic centimeter with needle + fluid to measure how much are milliliter/
cubic centimeter in the combustion camber with piston on TDC.
Milliliter = Cubic centimeter.

As you wrote your engine has about 15:1, also the engine has about 0,77 cubic centimeter, then you can adjust the height of gasket and measure how much is the compression ratio with measured amount of milliliter or cubic centimeter. If you need 20:1, then the combustion camber will take 0,567 milliliter (nearest 0,57 milliliter).

Note: The fluid must not be higher than the edge of the hole in the combustion camber where the injector will be there.

0,77 ml and 0,567 ml are not very big difference in volume, then add thickness in millimeter in the calculator "Head gasket thickness(t)" + "Gasket bore (g)" to learn how thick you need to set the required compression ratio in your engine.

With fixed 0,5 cc (without gasket) in combustion camber with the thickness of gasket will give the compression ratio:

0,96 mm gasket --> 14,95:1
0,24 mm gasket --> 19.95:1

Last edited:

#### Steamchick

##### Well-Known Member
HMEM Supporter
3 to 5 bar??? Not correct, common rail diesel engine has a maximum 1200-1500 bar. To start up the engine 200-250 bar and normal use can be varied between 300-500 bar depending on the brand of common rail diesel engine.
Thanks for the correction...
K2

#### Steamchick

##### Well-Known Member
HMEM Supporter
Just browsing the web... as when I worked in the factory lab, my colleagues made diesel fuel for exacting test purposes by blending a base oil (Paraffin/Kerosene?) with a "10%" cocktail of napthaline stuff, and other aromatic stuff, and some lubricating oil.... I don't know the recipe but one single jar of stuff was the strong aromatic smell of DERV you get from fresh pump fuel. I noticed that some Derv I have had in the garage for a few years, no longer has the sharp aromatic smell, and I was told that the chemical was the bit that made DERV easier to ignite when injected. (I'm sure someone will know the stuff?).
More info... https://www.chevron.com/-/media/chevron/operations/documents/diesel-fuel-tech-review.pdf

I saw a TV presentation where to use cooking oil in a diesel car, they added a cup-full (250ccs?) of "Turps substitute" to each Imperial gallon (4.5Litres) of cooking oil... "for easy starting"....
SO knowing that road fuel has additives for "easy starting" and "home-made" alternative fuels need the same, maybe the arguement about Minh-Thahn's using a bit of Ether in the paraffin for easier running isn't such an issue?
I would suggest that any way the the ignition is initialised by the heat of compression qualifies as a "diesel" combustion - defined by the combustion cycle determined by Rudolf Diesel I.E.

Should this be assisted by a "hot-zone" in the engine caused by a hot glow-plug (even when not electrified) or by a "special zone" in the combustion chamber (such as the Ricardo pre-combustion injection chamber?) it still qualifies as "a diesel" as without the major heating of the gas by compression, the ignition of the fuel-air mix cannot be created.
Considering that "Diesels" (compression ignition engines) run on everything from Ether-paraffin mixes (as for model aircraft - without glow-plugs) through to heavy oils that need steam/electrical pre-heating in order to flow in the pipework and injectors (as used on large ships), then maybe a comment about the use of ether is just a little prejudiced?
I'm sure this will cause some reaction, but "in my naivety" I hope I don't offend anyone?
K2

#### minh-thanh

##### Well-Known Member
Mechanicboy ,Steamchick !
Thanks !

Hi Mechanicboy !

Until now, I can tell you: Maybe the way my diesel engine is built and the way it runs is different from him
Don't give his data or videos as a reference...for me.
Don't ask me why, but please
Again, I always welcome, appreciate and thank you for your comments , of all people , but beyond what I just said above

This is probably my most stupid statement and I'll probably get hate for it
Find Hansen diesel engine has a pump stroke at 0,03 mm under idling.
Ser at this engine how to set timing..
should be between 45 and 55 degrees before TDC. His diesel engine is set at 45 degrees before TDC can set up to 55 degrees, but the lever with excenter at the fuel pump (see at the movie) can be adjusted 15 degrees in the area where it runs best without getting an ignition knock.

Last edited:

#### lennardhme

##### Well-Known Member
Hi all,
In Oz we have a great spray product called , 'Start You Bastard', mostly ether I think.
Lennard

#### Mechanicboy

##### Well-Known Member
About compression ratio, do not jump right away from 15: 1 to 20: 1, start with one step up at a time 16: 1-17: 1-18: 1 and so further to 20: 1 to find how big is the compression ratio is what you get the fuel to ignite by compression heat. So that you do not damage the engine by making a big leap direct from 15: 1 to 20: 1. Each engine construction is different when we talk about settings, compression conditions etc etc.

#### Mechanicboy

##### Well-Known Member
Just browsing the web... as when I worked in the factory lab, my colleagues made diesel fuel for exacting test purposes by blending a base oil (Paraffin/Kerosene?) with a "10%" cocktail of napthaline stuff, and other aromatic stuff, and some lubricating oil.... I don't know the recipe but one single jar of stuff was the strong aromatic smell of DERV you get from fresh pump fuel. I noticed that some Derv I have had in the garage for a few years, no longer has the sharp aromatic smell, and I was told that the chemical was the bit that made DERV easier to ignite when injected. (I'm sure someone will know the stuff?).
More info... https://www.chevron.com/-/media/chevron/operations/documents/diesel-fuel-tech-review.pdf

I saw a TV presentation where to use cooking oil in a diesel car, they added a cup-full (250ccs?) of "Turps substitute" to each Imperial gallon (4.5Litres) of cooking oil... "for easy starting"....
SO knowing that road fuel has additives for "easy starting" and "home-made" alternative fuels need the same, maybe the arguement about Minh-Thahn's using a bit of Ether in the paraffin for easier running isn't such an issue?
I would suggest that any way the the ignition is initialised by the heat of compression qualifies as a "diesel" combustion - defined by the combustion cycle determined by Rudolf Diesel I.E.

Should this be assisted by a "hot-zone" in the engine caused by a hot glow-plug (even when not electrified) or by a "special zone" in the combustion chamber (such as the Ricardo pre-combustion injection chamber?) it still qualifies as "a diesel" as without the major heating of the gas by compression, the ignition of the fuel-air mix cannot be created.
Considering that "Diesels" (compression ignition engines) run on everything from Ether-paraffin mixes (as for model aircraft - without glow-plugs) through to heavy oils that need steam/electrical pre-heating in order to flow in the pipework and injectors (as used on large ships), then maybe a comment about the use of ether is just a little prejudiced?
I'm sure this will cause some reaction, but "in my naivety" I hope I don't offend anyone?
K2
When Minh Thanh added ether in paraffin, he has increased the cetane number which makes it easier to start his diesel engine.

The cetane number
Cetane is the term that shows the ignition of the diesel, and note that most engine manufacturers require a cetane number of 50. This number is a limit value, but numbers lower than 50 give a poorer ignition of the diesel and in addition the ignition process will be disturbed. Modern engine constructions have, however, partly managed to remedy the fact that the diesel construction has not been able to follow up the development that has taken place in the area of the engine construction. Additives that increase the cetane number improve cold start properties, reduce white smoke during start-up and even reduce engine noise!

However, not all countries have access to ether due to strict laws in connection with ether being used for drug production.

Ether is not cheap to obtain and costs a portion per quantity. Paraffin is the cheapest and is more liquid than diesel oil that it atomizes more easily in the smallest model diesel engine with injection equipment (do not think of model diesel engine with compression screw to adjust compression ..).

In Norway, we have winter diesel to make it easier to start the cold diesel engine.
Diesel has a very high boiling point (180-360 degrees), but it is worse when it is cold. This is about something called the fog point (when the fuel starts to get foggy). This is because in the cold wax crystals begin to form. Fuel system, with filters. pipes and pumps, do not benefit from solids. The crystals are so small that they pass system filters with ease. As the temperature drops, the problems increase - until there is so much wax that a blockage occurs. This is why diesel is adapted to the seasons with summer diesel and winter diesel. Winter is therefore a challenge for diesel engines. Therefore, a larger proportion of hydrocarbon molecules are mixed with shorter carbon chains and lower fog points. In the old days, paraffin was often added to diesel, but this is no longer possible due to the paraffin's high sulfur content. Self-mixing of paraffin is strongly discouraged, as this can lead to breakdowns of high-pressure pumps and injection nozzles and damage to the particulate filter and catalyst due to the sulfur content. Flow-improving substances are also added to the diesel which prevent the wax crystals from clumping together.

In ordinary diesel, 7% biodiesel is mixed in based on rapeseed oil (winter diesel). The diesel used in construction machinery and leisure boats does not have biodiesel, because such a mixture absorbs water more easily, and it can pose a risk of bacterial growth in the fuel system. The element of biodiesel also means that the diesel "goes out of date". A diesel car should not stand still for more than half a year without a new tank filling.

Glow plugs are used to start up when the temperature becomes too low for the engine to suck ice-cold air into the cylinders and be controlled by the temperature sensor in modern cars. Common rail diesel engine has glow blug due cold weather in Norway in winter and controlled by ECU.

Richardo precamber needs high compression ratio up to 23: 1 to 25: 1 and it has glow plugs to start the engine. The injection needle has a pin outside the injector to distribute around inside the precamber. Also not practical in model engines due dimension is too small.

#### ajoeiam

##### Well-Known Member
When Minh Thanh added ether in paraffin, he has increased the cetane number which makes it easier to start his diesel engine.

The cetane number
Cetane is the term that shows the ignition of the diesel, and note that most engine manufacturers require a cetane number of 50. This number is a limit value, but numbers lower than 50 give a poorer ignition of the diesel and in addition the ignition process will be disturbed. Modern engine constructions have, however, partly managed to remedy the fact that the diesel construction has not been able to follow up the development that has taken place in the area of the engine construction. Additives that increase the cetane number improve cold start properties, reduce white smoke during start-up and even reduce engine noise!

In Norway, we have winter diesel to make it easier to start the cold diesel engine.
Diesel has a very high boiling point (180-360 degrees), but it is worse when it is cold. This is about something called the fog point (when the fuel starts to get foggy). This is because in the cold wax crystals begin to form. Fuel system, with filters. pipes and pumps, do not benefit from solids. The crystals are so small that they pass system filters with ease. As the temperature drops, the problems increase - until there is so much wax that a blockage occurs. This is why diesel is adapted to the seasons with summer diesel and winter diesel. Winter is therefore a challenge for diesel engines. Therefore, a larger proportion of hydrocarbon molecules are mixed with shorter carbon chains and lower fog points. In the old days, paraffin was often added to diesel, but this is no longer possible due to the paraffin's high sulfur content. Self-mixing of paraffin is strongly discouraged, as this can lead to breakdowns of high-pressure pumps and injection nozzles and damage to the particulate filter and catalyst due to the sulfur content. Flow-improving substances are also added to the diesel which prevent the wax crystals from clumping together.

In ordinary diesel, 7% biodiesel is mixed in based on rapeseed oil (winter diesel). The diesel used in construction machinery and leisure boats does not have biodiesel, because such a mixture absorbs water more easily, and it can pose a risk of bacterial growth in the fuel system. The element of biodiesel also means that the diesel "goes out of date". A diesel car should not stand still for more than half a year without a new tank filling.
Re: cetane number
Can find docs for the minimum cetane number - - - - can't find any regarding the recommended range.
There was some mention that a higher cetane number increases the flammability and the likelihood of greater explosiveness.
My guess would be that mixing to get a very high cetane number would negatively impact the longevity of the engine - - - you would be creating pre-combustion when comparing to a standard #2 diesel.
Biodiesel also increases the likelihood of bacterial contamination. The recommendation that I was told was diesel shelf life is now approximately 3 months (with gasoline being maybe a month). Some fuel additives are useful - - - - most of such are snake oil.

Dunno about Norway but in north western Canuckistan there is NO bio-diesel in winter fuels. Biodiesel (that made from canola (likely also rapeseed) that from soy oil gels at slightly higher temperature which I don't remember) gels (coagulates) at some -18 C (IIRC) and some of the biodiesel variants can gel at far warmer temperatures ( ie those made from rendered fats). So winter fuels contain NO biodiesel. Dunno about every refinery or for every area but what was available was diesel in the following (from summer to the lightest grades)
1. #2 summer diesel rated to -20 C
2. (dunno if it was still called #2) fall diesel rated to -30 C
3. winter diesel rated to -40 C
4. arctic diesel rated to -60 C

I have experienced it only a few times but have seen very long lines of semis parked idling in very cold windy weather as when they started moving the effective temperature on the tank lines was so low that gelling occurred. Usually lasted less than 24 hours but if you've ever had the joy of needing to change the fuel filters (all of them) and then bleed everything, one step at a time from lift pump to filters to injection pump (sometimes needing to do well more than one line) and ending at the injectors (again sometimes needing to do more than one line) you just really don't want to ever have to do that again. Can't remember how long it took in my worst instance but I do know that I very carefully track my fuel characteristics and make very very sure that my fuel is fit for intended use characteristic.

I have a complete copy of the ASTM standards for all the fuels and lubricants here in my collection. There are 4 volumes in total - - - some 6" stack of office paper sized pages. These are not to hand or I would check for 'official' standards.
No idea when fuels move from #2 to #1.
Also don't remember the characteristics for jet fuel either.
Remember that #5 and #6 diesel or bunker fuel seemed to me to be far closer to crude oil than anything actually refined. Thought it interesting that such needed to be heating and run through a separation system before use - - - the stuff doesn't move at 'normal' operating temperatures.

#### Mechanicboy

##### Well-Known Member
Biodiesel from vegetable oil sources have been recorded as having a cetane number range of 46 to 52, and animal-fat based biodiesels cetane numbers range from 56 to 60. Dimethyl ether is a potential diesel fuel as it has a high cetane rating (55-60) and can be produced as a biofuel.

Generally, diesel engines operate well with a CN from 48 to 50. Fuels with lower cetane number have longer ignition delays, requiring more time for the fuel combustion process to be completed. Hence, higher speed diesel engines operate more effectively with higher cetane number fuels.

In Europe, diesel cetane numbers were set at a minimum of 38 in 1994 and 40 in 2000. The current standard for diesel sold in European Union, Iceland, Norway and Switzerland is set in EN 590, with a minimum cetane index of 46 and a minimum cetane number of 51. Premium diesel fuel can have a cetane number as high as 60.

In Finland, premium diesel fuels sold by Filling station chains St1 (Diesel Plus), Shell (containing GTL) and ABC (Smart Diesel) have a minimum cetane number of 60 with the typical value being at 63. Neste MY Renewable Diesel sold in Finland has a minimum cetane number of 70.

Winter diesel..

Norway has adopted the European standard into its national NS-EN 590 standard. In the mid winter period the standard diesel fuel must meet the arctic winter diesel class 2 conditions (Vinterdiesel Arktisk Grad 2). The time frames may be extended in some regions by about ±14 days.

For the "arctic" climatic zones, the EN 590 standard defines five classes from 0 to 4. In Scandinavian countries, the winter diesel (Vinterdiesel) must meet Class 2 conditions. Some refiners offer both standard winter diesel and arctic winter diesel in parallel, commonly differentiated as Winter Diesel (Winterdiesel, diesel d'hiver) and Arctic Diesel (Polardiesel, diesel polaires). The low cloud point (CP) of EN 590 ensures that wax particles do not precipitate to the bottom of the tank upon standing because daytime temperatures might melt them together. Properties beyond Class 4 would require a kerosene type fuel with a low cetane number (at least 45 in EN 590).

Biodiesel fuels are unsuitable for use in colder regions because they have a higher measure of saturated fatty acid methyl esters. To be utilized in low-temperature conditions, the biodiesel fuels should have both lower CFPP values and less saturated fatty acid content

#### Steamchick

##### Well-Known Member
HMEM Supporter
I was thinking about this too .
Do you know how much more effective it can be ?
Try this? - or research the "Ricardo Comet pre-combustion chamber".

K2

#### bluejets

##### Well-Known Member
For example kero is quite expensive over here in Australia as it’s only available in 1 or 2 litre bottles. It used to be available at the bowser in service stations years ago but it’s not used all that much here anymore.
1 litre Bunnings ...\$4.60

20 litre drums available at any fuel depot such as BP. (around \$70)

Some tractors still run on kero and I wouldn't be surprised to see 44 gallon drums at the same depots.

#### moose4621

##### Member
1 litre Bunnings ...\$4.60

20 litre drums available at any fuel depot such as BP. (around \$70)

Some tractors still run on kero and I wouldn't be surprised to see 44 gallon drums at the same depots.
Jet A1 at your local aerodrome.

#### Steamchick

##### Well-Known Member
HMEM Supporter
1 litre Bunnings ...\$4.60

20 litre drums available at any fuel depot such as BP. (around \$70)

Some tractors still run on kero and I wouldn't be surprised to see 44 gallon drums at the same depots.
I bought 4 litres for £7 at my local camping shop... (It is used in old designs of cooking stoves and blow-lamps.) - I use it as a cleaning fluid, and as fuel for my paraffin blow-lamps for silver soldering boilers. - as many as 3 for general furnace heating,. than a propane lamp for the actual joint raised to a higher temp for soldering. - The Propane costs £35 for 7kg (~10l).
Road diesel fuel is £1.42 per litre for comparison: Paraffin leaves a dry metal surface (EG. for painting) when used for surface cleaning. Road diesel fuel leaves an oiled surface - which doesn't rust so quickly - but doesn't accept paint.

K2

#### Steamchick

##### Well-Known Member
HMEM Supporter
More Ricardo combustion chamber original designs.
He developed better combustion chambers to reduce knock:
And swirl chambers to increase power and good combustion:

enjoy.
K2

#### minh-thanh

##### Well-Known Member
Hi All !
An update:
I have conquered a real challenge : Diesel engine 10 cc .

Thanks everyone !

#### Steamchick

##### Well-Known Member
HMEM Supporter
Minh Thanh: A brilliant conclusion. Just needs a generator and lamp to use all that power...!
When will you publish final plans?
I'd like to also express my thanks as I have learned a lot about diesel engines from the input from many experts.
K2

Very nice !!!

.

#### ShopShoe

##### Senior Member
minh-thanh,

Congratulations on getting this engine completed and running. I have been following along and I wasn't sure how it would turn out.

Your skills are getting up with the top buiilders now.

I appreciate your sticking with this project and bringing it to this point.

--ShopShoe