# Another try to build an engine running with diesel fuel



## Chicken (Dec 4, 2014)

Hi All!

Probably everyone here knows the excellent small hot bulb and diesel engines from Find Hansen.

I've already built several IC engines, but all of them running with regular gas and electronic ignition. Actually I don't like electronic ignitions as a battery is always required, and sometimes when I want to run my engines I end up with a empty battery and no fun. 
I also made some experiments with piezo ignitions from lighters. They work ok, but are sensitive and usually fail after some few hours of operation.

Of course we all can easily build model diesel engines with regular carbs, running on diethylether fuel, but I don't like the smell of that stuff.

So here my next go to build a real diesel or hot bulb engine running on regular diesel fuel without any electronic components, similar to Find Hansens Engines and of course I want to share my experience.

I already tried to build a 2-stroke hot bulb engine with 30 cc displacement, but totally failed to get a good spray from the injector with such small diesel amounts and it ended up to be a 2-stroke gasoline engine with electronic ignition.

My new project is somehow based on a hit&miss engine I build 2 years ago. It will have a stroke of 60 mm and bore of 46 mm, which makes 100 cc displacement. I thought that a larger diesel engine should be easier to build than a small one.
I got a cast iron base, 2 large flywheels (30 cm diameter, 10 kg each ), and some raw bearing supports:







The rest of the engine is my own design. I already started last winter, but production stalled in summer as I prefer to be outside then 

I started of to build the crankshaft. I usually make them from several pieces. I use 2 steel blanks for the crank webs, weld them together on several small spots and drill the holes for the crank pin and crankshaft in one setup so they are exactly parallel.






After that I machined the crank shaft and crank pin, separated the two crank webs and put everything together with some loctite just to hold everything in place. I now cross drilled the crank webs and put dowel pins through both crankshaft and crank pin like this:






I now machined the crank webs to their final size and sawed out the piece of crankshaft between the 2 crank webs. Using this method I already prouced many good crank shafts, this one has a run out of less than 0,02 mm from end to end, which is acceptable I think.






I continued to machine the bearing supports, the base and the cylinder angle bracket. The crankshaft runs in cast iron bushings and with good lubrication I think this should run fine. After everything was machined a test fittet everything and was happy that the crankshaft with the flywheels turns smoothly.






Next I machined the cylinder out of some junk metal with a steel liner. The liner will be watercooled.






I continued with the cylinder head which is also made from a junk steel blank. I pressed in bronze valve cages. I made the valves from a piece of drill rod and silver soldered a bronze head onto it. With bronze valve cages and bronze valve heads you will never have any corrosion issues due to moisture or something.






I continued with the connecting rod, which I also make from several parts. First I made a cast iron blank for the big end bearing and drilled all holes and threads for the bearing cap. I basically made the same for the piston pin side. Both bearing blanks were now connected with a piece of steel bar. The steel bar has threads on both sides and threads into the big end and piston pin bearing. The thread is very tight and additionally secured with some loctite. Finally, I drilled the piston pin and crankshaft bearing in one setup so everythin is parallel again.
I was planning to make my own piston and rings, but found a 46 mm piston with rings and pin from an old motorcylce in my shop. As I had no other use for this piston, I decided to use it in this engine.
After putting everything together, I was happy that still everything turned nice and free.











Next, I machined another plate which holds the rocker arms and wich has a cooling water channel at the bottom side, so the cylinder head is sufficiently cooled. I made the rocker arms from some flat steel. The camshaft runs just below the cylinder head and will be driven by a roller chain. I milled the cams similar to some I made for earlier engines. A third cam will drive the injection pump. Currently, the cams are loose on the camshaft, as I need to have the roller chain first to correctly set the valve timing. After that, I temporarly fix the cams with some loctite, then cross drill them and ad a pin.











That's the state of the art right now. The next work will be the correct valve timing, cam for the injection pump, injection pump and injector and A hot bulb. I deciced to build a hot bulb engine, as it requires lower compression and should be better for a first go. Hot bulb engines also don't need a perfectly atomized fuel and the injection timing can be set to whatever timing and the engine should run. I want to try an injection at 180° before TDC, so the diesel fuel has enough time to evapourate.
Of course, I also need a centrifugal governor which controlls the amount of injected fuel.

I'll keep you updated, as soon as I have some more parts finished.

best regards,
Alex


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## Cogsy (Dec 4, 2014)

Very interesting. I'll be following along with this build. Looks good so far.


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## ZAPJACK (Dec 4, 2014)

Great project !!Thm:
 Witch compression ratio you will keep?
 You can fit the "hot bulb" with a glow plug
 Cheers
 LeZap


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## Chicken (Dec 4, 2014)

Thank you!

I want to go with a 10:1 compression ratio. Using this rather high compression for a hot bulb engine should reduce the required heat of the hot bulb. The hot bulb will be heatet with a small propane blow torch. A small propane tank and the blow torch will be permanently attached to the engine.


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## ShopShoe (Dec 4, 2014)

This looks very interesting. I will be following.

--ShopShoe


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## Herbiev (Dec 4, 2014)

Looking great. Following with interest


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## Chicken (Dec 5, 2014)

Hi all,

the valve setup is mostly finished now and working great.






The last days I started with the hot bulb system. Find Hansen says that he uses an indirect injection into some kind of vapourizer tube. My build will be different though with a direct injection into the hot bulb.

I made some kind of hotbulb holder, which threads into the cylinder head, see the following picture.






The threaded bolt you see is actually a tube and will connect the hot bulb and injector holder to the cylinder head. It turns freely in the holder and its an allen screw. The hole opposite the bolt allows me to tighten the screw. I silver soldered a threaded sleeve into the hole. The threads inner diameter is just big enough so I can fit the allen key through there. The hole will be closed with a screw once everything is mounted. The 4 small screw holes you see will hold the actual hot bulb.
Opposite to the hot bulb end there is a thread for the injector which will hopefully inject the diesel fuel directly into the glowing bulb:






I will drill 2 small water channels just next to the injector thread, so the injector will also be watercooled.

I don't really have an idea yet how my injector and injection pump will look like, but I will have a first try this weekend once I've finished the hotbulb.

stay tuned and best regards,

Alex


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## Chicken (Dec 6, 2014)

Today I managed to finish the hot bulb setup, injector and injection pump.

The injector is now watercooled, so it won't overheat during operation. The hot bulb itself is just some normal steel. It's fairly thin walled, so I hope it will stay hot enough to keep the engine running without any additional heat.






The whole assembly attached to the engine. It ended up a little cramped, but just enough space to fit in between the valves 






The injector is an open style injector with a non-return valve, so the compression and combustion pressure does not push any air into the fuel system. The nozzle bore is ~ 0.1 mm. I drilled 0.3 mm, but not completely through. I then removed some material with a good mill until the hole became just visible. The nozzle is threaded into the injector body, so I can replace it just in case the spray is not good enough. If I use a syringe with some diesel and push it through the injector I get a good atomization, so I'll just give it a try with this nozzle.






Here is a picture of the nozzle tip. The thread is 6 mm, the nozzle bore is just visible:






The injection pump is a simple plunger type pump with a 3 mm piston. It has 2 mm ball valves. It's quite difficult to get a good tight, but still easy moving fit of the piston in the pump body. I used a good reamer and it appears to work fairly well. If I fill the pump body with diesel, I can't push the piston in by hand, so I guess the fit is OK.
in 100 cc of air about 10 µL of diesel can be burned. As the plunger is 3 mm, at maximum power it will have to move about 1,5 mm to pump this amount of diesel. At idle speed, the stroke will be much less of course. This will be controlled by a centrifugal governor, which will be the next part that needs machining.






The injection pump in parts and fully assembled:






best regards,
Alex


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## Rustkolector (Dec 6, 2014)

Chicken,
Very ambitious project. I have an old M&W 2 stroke hot bulb engine. It is low compression (~65 psi) and uses injection very early in the compression stroke. It however, injects a solid stream of fuel directed against a splatter plate adjacent to hot bulb port to atomize the fuel. The piston then pushes the fuel mist into the hot bulb. Combustion begins when ever things are right in the hot bulb which would vary greatly with load. Hence the requirement for a very low compression ratio to minimize the hazards of pre-ignition.This system had very low efficiency. It has been estimated that this design pushed about 40% of the fuel up the stack unburnt. However, the design did serve its intended purpose which was to provide an engine that burned less expensive kerosene and was safer to use than gasoline which the insurance companies liked. Later design hot bulb engines used timed injection directly into the hot bulb. With more precisely timed injection, the compression ratio's could be increased providing much higher efficiency. Using injection directly into the hot bulb starts combustion immediately upon injection so it will require injection at or just before TDC, and not at 180 degrees BTC as you suggested. 

Jeff


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## Chicken (Dec 7, 2014)

Thank you for the advice. I will make the injection cam adjustable, so I can change the injection timing.
I'm copying a bit from the hot bulb design of a Lanz Bulldog, here the injection is ~ 130° before top dead center directly into the hot bulb. Pre ignition can't occur as the hot bulb is still filled with exhaust gas during injection. Combustion starts once the piston is pushing fresh air into the hot bulb. Of course the combustion is not really controlled, but still working fine. I think the same will occur in my small engine, so maybe an early injection is not that critical.


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## Rustkolector (Dec 7, 2014)

Chicken,
The Lanz tractor is a 2 stroke engine with compression at about 5:1. That is similar to the M&W engines which used early injection. The 2 stroke FM Y engines used a 10:1C/R and used timed injection near TDC. I am not sure what other differences there might be between those two designs. With your engine design being a 4 stroke, it could allow enough air scavenging within the bulb to allow combustion on injection. Anyway, I think allowance in your design for injection timing variation is prudent. Good luck with your project. I will be watching your progress. 
Jeff


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## Chicken (Dec 7, 2014)

Dear Jeff,

thank you for your fine comments, maybe you are right. I have 2 Lanz Bulldogs, one with a 10,5 liter hot bulb engine (45 hp), the other with a 7,5 liter (60 hp) "Lanz Diesel", which is some kind of hybrid between hot bulb and real diesel engine (direct injecting 2-stroke, but uncooled cylinder head. It's started with a diesel/gas mixture and electric spark and turned to pure diesel after a few minutes of operation, the spark is then turned off). the 10,5 liter hot bulb has a 7:1 compression ratio and injection is 130 ° before TDC, the other is 11:1 and 20° before TDC. Of course, both lanz engines are 2-stroke.
I have no idea how my small 4-stroke engine will behave, so I think the best idea is to make the injection cam adjustable and then find the best timing by trial and error.

best regards,
Alex


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## Chicken (Dec 11, 2014)

Hi!

Today I had some time to start with the centrifugal governor and machined the 2 pivots holding the governor weights.
My governor will be similar to a bosch type diesel governor:






my governor will run directly on the camshaft and change the stroke of the injection pump.
In the meantime I have also recived a roller chain and some chain wheels, so the whole cam setup can also be finished now.






best regards,
Alex


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## Chicken (Dec 14, 2014)

Hi!

The centrifugal governor is now fully assembled. I had to make quite heavy weights, as it runs directly on the camshaft. I want to have the engine running at 400 rpm idle, so the governor needs to work properly at ~200 rpm. Tried it out on my lathe and from 150 rpm onwards it works ok.
In the meantime I have also bored the chain wheels to match my design. After adjusting the cam layout I've pinned them onto the camshaft. The injector cam has a set screw now so I can change the injection timing.






This weekend I could also mostly finish the injection setup. The centrifugal goveror moves a conical bar which then limits the injection pump stroke.
In the following picture you can see the setup with Injection pump, injection pump plunger that is operated by the camshaft, camshaft bearings and conical bar (the cone is in the inside of the plunger housing). The governor will regulate the injection pump stroke between 0 and 1,6 mm.






best regards,
Alex


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## MCRIPPPer (Dec 14, 2014)

this is a very cool build. too bad find hansen wont share how he crated true diesel engines.


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## nowramfg (Dec 16, 2014)

I too am following this..with great interest


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## gus (Dec 18, 2014)

Hi Chicken,
Would love to see this diesel engine running.


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## Chicken (Dec 19, 2014)

Hi!

Today I ran into a problem. I finished the governor setup and tested everything on my lathe. It does actually work, but due to the low rpm on the camshaft, the governor response is very slow. Probably way too slow to have the engine running nicely. I'll see how I can change this over the weekend...

best regards,
Alex


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## Chicken (Dec 20, 2014)

Hi!

Things like that seem to happen when building an engine without any plans 

anyway I have found a solution for my problem. I've made a second shaft just parallel to the camshaft which will hold the centrifugal governor. It will be gear driven from the camshaft with a 1:3 gear ratio. This should solve the governor lag problems.
Now I just need to cut 2 small gears...


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## MichaelWilliams (Dec 20, 2014)

Hi ,

Just a few thoughts :

(1) A true diesel is unlikely to function at all with a compression ratio less
than about 9:1 .

(2) A true diesel engine which is hot requires a lower compression ratio to
keep going than a cold engine does to start up . For this reason
various methods have been devised to make engines start
more easily .

(3) The two most common methods are :

Preheating cylinder head and inlet manifold .

Using a temporary supply of more ignition friendly fuel such as
petrol .

(4) Various high and low tech methods have been devised over the years
to make diesel engines run at lower compression ratios . Some of
these are :

Preheating diesel in hot injector to be quite near ignition temperature .

Flame injection and flame pocket ignition helpers .

Catalytic ignition .

(5) Just a bit of personal history :

I come originally from a country district of South Wales - then an
active farming area . Not long after the war and there were many
and varied diesel/tvo tractors in use - mostly worn out wrecks .

Starting any of these on a winters day was difficult indeed . I
remember seeing one of the more obstinate ones being started by
means of setting the c/o valve to petrol , wrapping petrol soaked rags
about the inlet manifold , setting fire to the rags and then the farmer
cranking the engine the engine like a madman . Took a few goes but
started in the end . Very dangerous and *Not *recommended !

Regards ,

Michael WilliamS .


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## Chicken (Dec 21, 2014)

Michael, my engine will be a hot bulb type engine with preheated hot bulb.

Progress: Finished the 1:3 gear with new governor shaft. the governor response is way better now.
Things left to do before 1st start attempt:

- fuel tank and fuel piping
- throttle lever which changes the tension of the governor spring
- spring loaded roller chain tensioner
- some lubricators
- hot bulb preheating system
- intake manifold












best regards,
Alex


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## Chicken (Dec 26, 2014)

Hi!

Not too much to report over Christmas. But I've managed to finish the roller chain tensioner. It's not spring loaded, but easily adjustable using a screw.






best regards,
Alex


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## Mechanicboy (Dec 26, 2014)

When start up the semidiesel engine, do not rotate the flywheel in direction of rotation. Bunch starting only, also prime the fuel one or two stroke of fuel pump and rotate the flywheel back until it will ignite and rotate in right direction. 

I owned the Sabb semidiesel (hot bulb engine).

 Diesel combustion engines can be divided into three main types:

Semidiesel engine with a glowing hot bulb. Compression ratio is 5-7 and fuel pump pressure ca. 80 kp / cm2

Semidiesel engine with a hot bulb. Compression ratio is 7-10 and the fuel pump pressure between 80 -150 kg / cm2.

Dieselengine: Without hot bulb. The appropriate compression ratio depends on the design of the cylinder head. The figure is usually between 14:1 and 16:1 for direct injection engines, and between 18:1 and 23:1 for indirect injection and fuel pump pressure between 105-650 kg / cm2 (Common rail diesel pressure up to 1500 kg/ cm2, to start up engine the fuel pressure is about 250 kg/ cm2)


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## Mechanicboy (Dec 26, 2014)

To adjust amount of fuel and timing.

White smoke: Too late ignition timing (Blue smoke: too much engine oil)

Black smoke/ hard knocking: Too early ignition timing

Glowing hot bulb under load, in case loss of power: Too much fuel 

Engine is running before it stopped and white smoke: 1: Not enough heat of the hot bulb, need more heat. 2: Loss of heat of hot bulb due the cylinder head is robbing the heat from hot bulb to example the cylinder head is wellcooled by coolingwater. The solvent: 1: Make long and thin wall body between hot bulb and cylinder head to prevent loss of heat in hot bulb. 2: Increase ratio of compression (If the engine is without  knocking under max load and poor/impossible idling means too low ratio of compression, a very weak of knocking under max load and idling is nice = ratio of compression is ok)

The injector in semidiesel is designed to regulate by operator: The atomized fuel is injected into the hotbulb under idling (ignite by hot bulb) and the thin beam of the fuel (unatomized) is injected into the cylinder under high revolution under load (ignite by compression).


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## Chicken (Dec 29, 2014)

Hi!
I recently mounted the engine onto a wooden board. Furthermore I have finished the Diesel tank which rests just below the cylinder. It has a little acrylic glass level indicator. The pressure line between injection pump and injector is also finished. It's made from 3 mm copper pipe.
The cooling water pump is also mostly done. It's an ordinary rotary vane pump and will be belt driven from the camshaft.
If it's finished then all that is left are some lubricators, so I'm getting closer to the first start attempt


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## Herbiev (Dec 29, 2014)

Looking forward to watching it run


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## Chicken (Jan 3, 2015)

Hi!

Ready for first start attempt:






Using a small propane burner I heated my hot bulb to dark red (barely visible).
I flipped the engine several times and got lots of white smoke from the exhaust indicating lots of evaporated diesel. In some cases, I also got some very weak combustion, but no real strong power stroke. I tried several different injection timings, but none was successful.
The injector spray is not the finest, but not too bad in my opinion?

What may be the reason that it never really started?
Some thoughts:

Compression too low. But actually it's a 10:1 compression?
Spray from the injector is too bad?
Bad injection timing, but I've tried many different positions?

Currently, I think the most plausible reason is a bad spray from the injector and thus bad fuel evaporation making it difficult to get a ignitable fuel/air mixture.

Do you have any other thoughs?

best regards,
Alex


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## Mechanicboy (Jan 3, 2015)

When you had the problem to start up the engine, the white smoke out of exhaustpipe (unburned fuel) means not enough compression of ratio or not enough heat by hot bulb. The engine will ignite when fuel is ignited by heat of hot bulb + right compression of ratio.

Try to raise up to 14:1-15:1. The hot bulb will evaporate the bad atomized fuel until it will ignite. Heat up the hot bulb to glowing before start up the engine.

Ignition timing can be varied depending on size of hot bulb and compression of ratio. Set first to 5 degree and for each 5 degree between start test up to 20-25 degree before increasing the compresion of ratio until the engine will run with correct timing and compression of ratio.

Edited due disturb by my childrens..


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## ZAPJACK (Jan 3, 2015)

Hello Eirik,
 On two stroke engine, especialy on "hot bulb" engine. there are theoric and real compression ratio.
 The first one is mesured between TDC and BDC, the second one start when transfer and exhaus port are closed.
 That's perhaps why à Lanz have "only" 1/6 compressio ratio
 LeZap


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## Mechanicboy (Jan 3, 2015)

ZAPJACK said:


> Hello Eirik,
> On two stroke engine, especialy on "hot bulb" engine. there are theoric and real compression ratio.
> The first one is mesured between TDC and BDC, the second one start when transfer and exhaus port are closed.
> That's perhaps why à Lanz have "only" 1/6 compressio ratio
> LeZap



In a small engine such as a model semidieselengine is much difficult due loss of heat is big than in big semidieselengine, need more compression of ratio. In a ship dieselengine to example Sulzer, the compresion of ratio is not high as in dieselengine made for automobile due the heat by compression in big engine is higher than small engine.


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## Chicken (Jan 4, 2015)

Hi!

Made some troubleshooting today. Looks like the intake ball valve of my injection pump is leaking a bit, so the whole system has problems working against the compression of the engine causing the injector to just poorly drip.
Also, the intake valve is not 100 % tight and causing some compression loss.
I'll get these things sorted and try again.


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## Mechanicboy (Jan 4, 2015)

Take the ball and give a light knock with the rod to form the valveseat (both inlet and outlet valveseat) inside the injectionpump. As rule the semidieselengine has a extra valve before entering into injection to prevent leakage caused by compression/pressure by combustion. Also 1 ball in outlet side and 1 ball before entering into injection.


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## Mechanicboy (Jan 4, 2015)

Here is the drawings of the injector who is used in Sabb semidiesel, it is not difficult to make the injector. The deflector is a angled disc who is rotated by operator to run engine in idling or under load. Under load with atomized fuel against hot bulb will make problem with engine, then rotate the deflector away from orifice then the fuel is ignited by compression. The disc is cooled by injector body under load. Forgotten to tell in early post, all the outlet valve is closed by spring, both the pump and injector . The injector is cooled by waterjack in Sabb semidieselengine, in modelengine try with less cooling to better evaporating of injected fuel, but no fuel is boiling inside the injectorbody.


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## Chicken (Jan 5, 2015)

Hi!

I'm struggling with the injection pump. Always, one ball or both balls are leaking. I tried to produce a good valve seat by giving them a light knock, but it doesn't seem to work. What's the best material to machine the valve seats? my first try was brass, But I feel it's not the best material.
My ball valves are 2 mm in diameter. Which diameter should the passage be drilled?

I thought the most difficult part of the injection pump would be a good tight fit of the plunger, but that was very easy. The ball valves are very challenging!

best regards,
Alex


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## Mechanicboy (Jan 5, 2015)

See at the picture how the valveseat is best for ball as valve, use brass or bronce, both is good as material. 2 mm ball is maybe too little for a big engine (unlike the Find Hansen engine who is about big as WEW engine when we are talking about bore/stroke) You can use 3-4 mm ball where the valve seat is not difficult to make with ownmade drill as i showed in the drawings. The angle is 90-110 degree in drill. And last work, give a light wack with rod on ball to make good tight between ball and valve seat. Use valvespring (thin wire, light springload on valve) to keep ball on place if your valveseat is in horizontal where the ball is not on place on valveseat due force of gravity. About passage: For a ball on 3 mm will i use 2-2,5 mm passage, 4 mm ball use 3-3,5 mm passage. And the hole size in valvehouse ballsize + 0,25mm-0,5 mm to example 3 mm ball drill 3,25 mm or 3,5mm hole in halvehouse. Fuelpassage no problem due fuelamount is very little for each stroke of injection.


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## Mechanicboy (Jan 5, 2015)

The other alternative is the valve same as you find in the dieselpump in dieselpowered car. The valve is very reliable and easy to make to your injectionpump. The valve is made of stainless steel from M6 bolt, valve seat in brass or bronce, the spring is made of stainless steel wire. After the job is done, lap the valve on seat with Autosol Chrome polishing paste or similar such as fine diamond lapping paste and clean up the parts free for dirt. Do not make groove on valve by lapping! Use all valves both inlet, outlet and before entering into injector.


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## deverett (Jan 6, 2015)

Rather than give the ball a whack, it may be better to burnish the seat.

Get a spare new ball - steel if your valve seat is bronze/brass - and glue it to a rod of a size that will hold the ball exactly central over the valve seat.  Turn the rod a few times in each direction by hand.  Do not use lapping compound.  This will put a minute flat on the valve seat that will be a mirror image of the ball surface.  Use a new ball for the valve.

Dave
The Emerald Isle


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## Chicken (Jan 6, 2015)

Hi!

It turned out that it's not the valve seats that are leaking! I'm using springs to retain the balls in place. I found that the ball valves will leak if the spring pressure is not 100 % dead on. Even if the spring is only distorted by < 0,1 mm, the uneven pressure on the ball will immediately cause leakage! The leakage is minimal, but already enough to spoil the whole setup. Consider that the maximum pumped volume is only 0.01 mL (10 µL)!
If I turn my pump 90° and just use gravity without any springs, the pump works well and builds up excellent pressure! Unfortunately in this position the pump does not fit into my setup. I will see if I can change this to use the pump without any springs.

best regards,
Alex


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## Chicken (Jan 7, 2015)

Hi!

Allright, I've played around with the injection pump the whole day and I think I came up with a version that is worth tying. I removed any springs and made the pump setup vertical, so only gravity will move the ball valves.
This pump now creates 100 bars easily and holds them several seconds, which is very good I think. I still use the 2 mm ball valves. While working on the pump, I ran into several more issues and I want to share my experience:

- Don't use springs on the injection pump ball valves. If the spring is not pushing perfectly dead on, there will be enough leakage to spoil the pump
- Don't use threads for the valve bodys or other parts of the injection pump. All parts must be soldered. Tiny bubbles of air can catch in the threads and turn the pump unuseable
- Make all passages as small as possible and avoid any sharp corners. Again, tiny bubbles of air can be trapped in narrow corners and they are very difficult to remove
- A tiny bubble of air anywhere in the pump will make it inoperative, bleeding the system almost took me 1 hour.

Now, I must also make a new injector. The current one works OK for larger amounts of fuel. But in the case of very small volumes, a drop may form at the nozzle tip. If a drop has formed, there is no spray anymore. The drop will just keep growing and eventually drip of the injector. I found that 1 drop is about 50 µL, which are 5 strokes of the injection pump at maximum flow rate.
I will now try to build a spring loaded injector that requires a certian pressure to open. This should solve any dripping problems.
Anyway I still have some hope to get this engine running some time!






best regards,
Alex


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## Mechanicboy (Jan 7, 2015)

I saw at the homepage to Find Hansen, there is not drawings. But i learned out by this homepage, the angle at injection valve was at 14 degree and opening pressure at 8 bar. You need the injector tester with manometer to rig up to adjust opening pressure and test the injector before use. The drawings is scematic only. As it works the small injector to inject the engine with high pressure to atomize the fuel. The fuel in Find Hansen hot bulb engine was turpentine or kerosene due thin viscosity (easier to atomize the fuel and ignite by hot bulb)


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## Chicken (Jan 10, 2015)

Hi!

A spring loaded injector is a real challenge. It's quite difficult to machine a needle with little taper that is perfectly round and furthermore drill a tapered hole that holds the needle. All things must be 100 % tight and the injector must make a squeaking sound when pumping fuel through it.
My first attempt is not too bad, but I call it a failure as the spray is one sided, so either needle or tapered hole are not 100 % perfectly round.
I will try again tomorrow...

best regards,
Alex


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## Chicken (Jan 25, 2015)

Hi!

It looks like I'm failing again. No matter what I try, I never get a useable spray from any injector. It doesn't matter if they are open injectors, or spring loaded injectors. Either they are just dripping or the spray is very irregular.

The frustrating thing: If I close the pressure hose by hand and push on really tight, I get the most beautiful spray one could imagine 

slowly running out of ideas now 

br,
Alex


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## Mechanicboy (Jan 25, 2015)

Dripping injector is not good. Lap the valve against valve seat with Autosol chrome paste to be sure the valve is tight against pressure before opening pressure is beginning. With other word, the pressure is build up in the injector before opening pressure to make a fine atomized fuel out of injector.


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## digiex-chris (Feb 12, 2015)

following along because I'm on the edge of my seat watching you troubleshoot. I have a feeling you're very close!


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## Chicken (Feb 15, 2015)

Hi!

There is some progress, but minor. I managed to get a sort of useable injector, but the spray is still too bad. I had the engine running for a minute or so. but excess soot forced my to stop it quickly. after this short time, the hot bulb built up quite some soot deposits. I tried a lighter fuel (kerosene), but that didn't make much difference.
I think the only way to solve this is to get a perfect injector which atomizes the fuel into the finest possible dust.

best regards,
Alex


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## Niels Abildgaard (Feb 15, 2015)

Find Hansen is using turpentine.Maybe easier for troubleshooting.

[ame]https://www.youtube.com/watch?v=UGksYSwFucI[/ame]


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## Chicken (Apr 4, 2015)

Hi!

long time no update, was very busy recently with other work.
I have a new injector now which sprays far more reliable than all my previous ones. It's also spring loaded with a fine needle, but 8 mm piston. The piston has an O-ring seal and the spring tension is adjustable. I'll see if there will be another start attempt in the next days.







best regards,
Alex


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## bigrigbri (Apr 8, 2015)

Nice prototyping there Alex.
Inspires me in my diesel build with this sticky area.


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## Mechanicboy (Apr 8, 2015)

Well done with injector. Hope your engine is running with the new injector. Add film while the engine is running in this forum..


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## Ripcrow (Apr 8, 2015)

Can I make stupid suggestion. Build your cam with four lobes. One for intake one exhaust one for driving injector and one that holds injector closed until firing. The lobe will work opposite to most cam lobes but ensures no leakage until up resource is right and allowed to open. Instead of a extended lobe the lobe just has a indent. Not sure how the governor or throttle works in as it puts a lit of pressure on opening and pumping setups


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## Mechanicboy (Apr 8, 2015)

Ripcrow said:


> Can I make stupid suggestion. Build your cam with four lobes. One for intake one exhaust one for driving injector and one that holds injector closed until firing. The lobe will work opposite to most cam lobes but ensures no leakage until up resource is right and allowed to open. Instead of a extended lobe the lobe just has a indent. Not sure how the governor or throttle works in as it puts a lit of pressure on opening and pumping setups



Same principle as the first diesel engine in 1897 with cam operated injector + airpressure to atomize the fuel into combustion camber. Unuseful in model engine.


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## Ripcrow (Apr 9, 2015)

Not quite. While the injector is still operating on pressure created by the cam driven pump the forth cam operates the opening. This way fuel is under pressure before the injector is allows to open instead of relying on a ball valve to hold pressure to a point before opening. This way fuel is under maximum pressure which should help with atomisation


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## Mechanicboy (Apr 9, 2015)

I discovered in your picture of injector, where is the return pipe from injector? The O-ring is not allways tight and can have leakage where return pipe wil lead the rest of fuel back to fuel tank under use.


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## Chicken (Apr 10, 2015)

Ripcrow, interesting idea, although maybe a little bit hard to regulate, as the pressure will decrease significantly with decreasing fuel amounts under no load conditions.

Jens, currently there is no return pipe. Currently there are no leaks past the O-ring yet, but for further testing  I need to find a stronger spring to increase the injection pressure. Maybe I can improve the spray pattern a little more. But now I'm very close to a running engine. Some new start attempts and hopefully also a video will come within the next few days 

best regards,
Alex


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## Mechanicboy (Apr 10, 2015)

Chicken said:


> Ri
> 
> Jens, currently there is no return pipe. Currently there are no leaks past the O-ring yet, but for further testing  I need to find a stronger spring to increase the injection pressure. Maybe I can improve the spray pattern a little more. But now I'm very close to a running engine. Some new start attempts and hopefully also a video will come within the next few days
> 
> ...



A correct adjusted injector will give a growling sound (sound as rrr-rrr-rrr) when pumping fast with a test pumping set (i am car mechanic). Maybe or no maybe in the model injector can make a growling sound when pumping fast under test, the importand is well atomized fuel out of nozzle.


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## Ripcrow (Apr 10, 2015)

Is your injector a unit injector or a pump separate to injector


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## Chicken (Apr 12, 2015)

Hi!

Today I tried to start it again, but sadly failed again 

I get a nice spray from the injector, engine compression is very good, I also get ignitions, but it just refuses to run.

As fuel, I again tried diesel fuel and a light kerosene, the result is quite comparable, the engine won't start on either, although kerosene produces less soot.

I don't know what else I should try. Maybe my combustion chamber geometry is bad.

Or maybe speed it up with a good power drill. Right now I always tried to hand start it.

Ripcrow: there is a separate injection pump.

best regards,
Alex


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## Ripcrow (Apr 12, 2015)

My thoughts are on a model engine a separate pump and injector won't be successful or at least take a lot of work to get it right


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## Stefan-K (Apr 12, 2015)

Hi chicken

Maybe the amount of fuel that is injected is still too much. Try to reduce the stroke of the injection pump. As a guide line look at the injection pump that Hansen uses. It's very very small. And that has a reason. 
Where are you from? 
Stefan


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## Stefan-K (Apr 12, 2015)

One more thought! 
The differential pressure between the combustion chamber and the fuel pressure must be very high. Otherwise you won't get any spray inside the combustion chamber. I. E. If your compression pressure inside the engine is let's say 20 bar and your fuel pressure is 25 bar, the difference is only 5 bar. That's not enough to form any spray inside the engine. The fuel will just form drops inside.  You must at least have the same difference in pressure that you have when you test your injector at normal room pressure. You can achieve this by adjusting the spring pressure of the injector needle. The bigger the difference the better it is.
Hope I could explain what I mean. 

Stefan


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## Mechanicboy (Apr 12, 2015)

In semidieselengine the fuel is hitting the hot part of hot bulb and there will evaporate and ignite fuel, in fact the semidieselengine is less sensitive for bad atomized fuel and will run. If the exhaust smoke is white, it means too much fuel or not enough compression of ratio. Is the hot bulb glowing before you tried to start the engine?

1: Adjust smaller amount of fuel
2: Increase compression of ratio
3: Reduce loss of heat from hot bulb to cylinder head


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## Mechanicboy (Apr 12, 2015)

Stefan-K said:


> One more thought!
> The differential pressure between the combustion chamber and the fuel pressure must be very high. Otherwise you won't get any spray inside the combustion chamber. I. E. If your compression pressure inside the engine is let's say 20 bar and your fuel pressure is 25 bar, the difference is only 5 bar. That's not enough to form any spray inside the engine. The fuel will just form drops inside.  You must at least have the same difference in pressure that you have when you test your injector at normal room pressure. You can achieve this by adjusting the spring pressure of the injector needle. The bigger the difference the better it is.
> Hope I could explain what I mean.
> 
> Stefan



Stefan..

This is wrote for the real diesel engine. 
In the semidiesel engine do not have adjusted fuelpressure for atomizing the fuel as we find in the diesel engine. 

The semidiesel engine has a pump who has a big diameter and short stoke to inject the fuel in short time, the fuel injector does not have the pop of valve to atomize fuel. The fuel under full load is not atomized and goes direct into cylinder, ignited by heat of compression. The fuel under idling is atomized or directed to hot part of hot bulb to evaporate and ignite the fuel. (Injector has 2 ways to select to inject into cylinder or hot bulb selected by operator depending on load of engine)


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## Chicken (May 4, 2015)

Hi!

Now this is so frustrating, I reduced the compression to 6:1, attached a carb and coil with spark plug, and it fired right away and runs perfectly smooth. Although my left flywheel wobbles quite a bit 

Anyway, here it is running on gasoline:

[ame]https://www.youtube.com/watch?v=7h2mRWFsjmY[/ame]

I will rework my whole hotbulb design. I think my heat isolation was too bad so I never reached the correct temperature to ignite the diesel.

best regards,
Alex


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## ShopShoe (May 4, 2015)

Your engine running as a hotbulb would definitely be interesting.

However, I think what you have achieved is a very nice looking and running engine even when running the way it is now. 

I especially like the way it sounds as it runs steadily on. It reminds me of the Oilfield engines.

Thank you for posting and I hope you keep pursuing the hotbulb idea.

Regards, 

--ShopShoe


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## Niels Abildgaard (May 4, 2015)

At what crankangle did You inject the fuel?
As I remember it was done sligthly after bottom dead center in hotbulb engines.
Try Youtube for         Hundested motor


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## Mechanicboy (May 4, 2015)

Niels Abildgaard said:


> At what crankangle did You inject the fuel?
> As I remember it was done sligthly after bottom dead center in hotbulb engines.
> Try Youtube for         Hundested motor



Niels..

We has still Hundested hot bulb engine in some fishing boats in Norway, these Hundested semidiesel engine has hot bulb or glow plug (to start engine without heat up the hot bulb only) to ignite fuel. Also the engine has high ratio of compression and do not need earlier begins of injection before TDC as you said after TDC who is common in low compression hot bulb engine.

In my earlier Sabb Semidiesel had a fuel injection begins at 5 degree before top dead center. Compression was high, impossible to turn the engine over TDC. 

Some hot bulb engine can have injection begins at 25-30 degree or more degree before TDC and some 10-15 degree or lower degree before TDC depending on how heat is the heat generated by compression depending on size of ratio of compression. 
In older hot bulb engine who has low compression then injection begins long before TDC and hot bulb engine to example after 1950 has high compression need injection begins not far away from TDC. 

Hot bulb engine ---> low compression, ratio of compression 5:1-7:1
Semidiesel---> High compression, ratio of compression 7:1-10:1

In model engine is much difficult to keep enough heat to ignite the atomized fuel by hot bulb due loss of heat via cylinder head and difficult to make the finest atomized fuel. Ratio of compression must be high than in the big engines.


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## Stefan-K (May 4, 2015)

Alex
Too sad that you gave up. 
I am convinced that you were very close to a running engine


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## ChrisLister (May 4, 2015)

Is there a way of using an oil nozzle from a central heating system to evaporate the fuel?
Greetings,
Chris


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## gus (May 5, 2015)

Runs like the old fashion single cylinder Ruston Engine very popular in the Malaysian Rubber Estates and Factories in the 50s and 60s. Made to last forever. No worry about spare parts,the machineshops can make the piston rings, remetal the main bearings and con-rod bearings. The gasket shops can custom make the copper clad outerhead gaskets but they don't come cheap.


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## Chicken (May 5, 2015)

Stefan, I did not give up. I will keep on trying. But I have to rework the whole hot bulb design, as I just loose too much heat to the cylinder head. Maybe some glass ceramic isolation will do the trick, or as with the engines of Find Hansen, a long, very thin walled stainless steel tube.

The test with gasoline was just to see if it runs in principle. And it does...


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