ESE's works engine tuner

[lucf]

The link is public on Facebook but in case it doesn't work, here is a part of this note which contains much replies from all over the world, incl. Jan Thiel, Frits Overmars and Ken Seeber.

FST a new twostroke design
Foekema Symmetric Twostroke


Forword
The first FST text was published on 19 january 2008. 3 month later on 16 March 2008 at 20.00hr the first FST engine was started in my home and my wife Hetty did make the movie on YouTube. One day later Jan Thiel called me to congratulate me, that was close before he went to Thailand.

first start of the engine March 16, 2008 https://www.youtube.com/watch?v=jtTc7sk8WS8

Now, more than 10 years later it is still not successful, yes it runs, but not in the way it should do. Partly due to the speed defined by the mixing of fresh and burnt gases, the fresh gases thus go too far directly into the exhausts. Therefore the temperature of the exhaust stays to low and so the speed can not increase further. It is therefore far from optimal cylinder filling and so it can have no power. Yes this was directly be heard during the first start and it was with adjustment, what I initially thought, not to get out. The solution must be sought in the process. The scavenging is also expected as very critical and needs to be improved in some way. And may be some day it will run, with new idees it is not impossible, I'm still working on it.

What do we know at this moment
1. In the 20s of the last century there were already engines with this system,
2. In the 50s there were Russian coxmotortjes model for this system,
3. In 1986 a patent for granted in England, but without a sequel,
4. Rotax has tested it expanded in 1989, without success
5. Frits Overmars has published his idee more than a month after my FST, and still he only has a printed cylinders. While he wrote in his publication: " Luc it is all about who has the first running engine "
6. He called it FOS, but should have called it VDS, because he got the idea from Cees van Dongen in 1969, that's why it took 30 years like he wrote.
7. Ken Seeber 29 July, 2013 wrote he had the idea in 1984, but not 100% TA, read below

And what about those engines in the 20's of mr Dolf. That answer is quit simple, those engines are not 100% TA and had no expansion exhaustpipes and therefore only runs in low engine speed with very low power. My prototype that runs after 2 months, had much more speed, but not enough, what it should be. Even without proper exhaust pipes like those Russian glowplug motors it can run for sure. However, in both cases, with much less port surface, with less engine speed and so very low power is available, what the real reason was to start this project.

What actions now?
Seen together it seems that it is never going to work. Does it still feel like there's still time to stabbing? From Frits I have not heard that he is going to stop it, much hurry he did not seem te have, after what is now known. Does it still make sense for me? No and Yes, No, because I do not have the impression that I could do it better than Rotax. Yes because I do have the engine, the cylinder and the exhaust pipes, so why not try something else? I am now 70 and still do not feel to be too old to learn. I'm looking for new idees to solve the current problems. Read below how it all started.


First publication of this new 2 stroke process
website: http://www.geocities.ws/lucfoekema/FSTsystemNL.html


Original text of January 19, 2008

FST a new twostroke scavenging system. About 2 years ago I got the idea to change the way of scavenging of the twostroke engine. The current way of scavenging exist almost from the beginnng of the 2-stroke history and never changed, unless the many other systems which had been founded. But thinking to get more power you automaticly come to new ideas. So to me it came about two years ago, and that is the Foekema Symmetric Twostroke (FST).

It was not my intention to announce this new idea before making and testing it, but I was supprised when reading the magazine of Kickstart of january this year. Frits Overmars also got a new idea, which he called the FOS system. When reading, I thought: "I'm not sure, but it could be the same". Lucky for me he didn't explain the system, otherwise he would be the first. May be it is different, than we will have 2 new systems at almost the same time. The idea is not very difficult, but realising ideas like this is not that easy, because it has to be made very precisely.
Many things in two-stroke tuning has been made since the beginning of the two stroke. That is why I thought that someone else already did the same in the past. Till sofare I didn't want to spend time for this because there are many more important things to do when you wanted to be the fastest 50cc sprinter in the world on the 150 meter and the 1/4 mile.

The only thing I did was an announcement on the Kreidler.nl site, but without an explenation. Also I did tell it to some friends. But because in the current circumstances, I can't wait to explain my new system. That's why I like to introduce you the "Foekema Symmetric Two-stroke" (FST)
Who would be the first realising the idea in a working prototype is another question. Althought this system should produce more power than the current way, it still is the question, if in practice this will be prooven.

FST scavenging
Symmetric is one part to explain the system, but most important is the 100% Time Area. The whole scavenging will proceed in a symmetric way. After burning the gasses, when the piston goes down, the 4 exhaustducts opens first at the same time and the burned gasses leaves the cylinder. These ducts are fully symmetric around in the cylinder, so the gasses can flow into the 4 exhaustpipes very fast. After that, all symmetric transfers opens also at the same time and fresh gasses flows from all directions right over the piston to the center of the cylinder. This result in a flow of the gasses in the direction of the chamber, while pressing the last burned gasses to the edge of the cylinder. In the chamber the fresh gasses will turn around in the direction of the four exhaust ducts, behind the burned gasses.
So two rows of fully symmetric and 100% Time Area ports. The upper 4 ports are exhausts, the lower row are transfers. Which results in much maximum Time Area capacity, which is 100%. There is no more room left for ducts.

Advantage of FST scavenging
The big advantage is that the whole scavenging will proceed much faster than in the current two-stroke way, because of the maximum TA capacity. That is why a much higher rpm is reacheable with the same or even a lower duration of exhausts and transfers.
Beside this there is another great advantage the symmetric scavenging keeps the temperature in the cylinder completely the same all arround. In the current way there are always risks that one side of the cylinder is more hot than the other side.

There is much more to read and to see if you follow the link, which is public, in Dutch and English
https://www.kiwibiker.co.nz/forums/s...post1131082527
https://www.facebook.com/notes/luc-f.../4085704360035
or here website, which is not up to date, because I don't have access anymore: http://www.geocities.ws/lucfoekema/FSTsystemNL.html

[SwePatrick]

The whole story after exact 10 years:
FST-twostroke-design https://www.facebook.com/notes/luc-f.../4080202582494

I can´t actually see how you could solve the problem, the column of air is far different from ordinary twostrokes.
As the column rises in the center of bore the it will be pulled down into exhaust both due to pipe suction and also by itself.
When column hits the combustionchamber and start heading downwards again near cylinderwalls it will actually decrease incoming column(because it 'rubs' against eachother) in speed hard and thereby it will be chaos and it all ends up in the exhaust with or witout suction from pipe.
Maybe it could be a little bit better if aiming all transfers the same way all around to build a swirl upwards in cylinder.

In my eyes, not worth spending money on.

[Haufen]

The link is public on Facebook but in case it doesn't work, here is a part of this note which contains much replies from all over the world, incl. Jan Thiel, Frits Overmars and Ken Seeber.

FST a new twostroke design
Foekema Symmetric Twostroke

Thanks for posting the information here. And thumbs up for your effort in daring to try the unknown in building and testing something new.

So, ten years later, could you show us some dyno graphs of the engine from testing? And a comparison between this engine and one with a conventional layout?
What were your findings? And how do you rate the potential of such an engine after your first hand experience? Which are the critical areas from your point of view?

In the best case, you might get some new input from the discussion here, in the worst case, you would have passed on your experience.

[lucf]

The link is public on Facebook but in case it doesn't work, here is a part of this note which contains much replies from all over the world, incl. Jan Thiel, Frits Overmars and Ken Seeber.

FST a new twostroke design
Foekema Symmetric Twostroke


Forword
The first FST text was published on 19 january 2008. 3 month later on 16 March 2008 at 20.00hr the first FST engine was started in my home and my wife Hetty did make the movie on YouTube. One day later Jan Thiel called me to congratulate me, that was close before he went to Thailand.

first start of the engine March 16, 2008 https://www.youtube.com/watch?v=jtTc7sk8WS8

Now, more than 10 years later it is still not successful, yes it runs, but not in the way it should do. Partly due to the speed defined by the mixing of fresh and burnt gases, the fresh gases thus go too far directly into the exhausts. Therefore the temperature of the exhaust stays to low and so the speed can not increase further. It is therefore far from optimal cylinder filling and so it can have no power. Yes this was directly be heard during the first start and it was with adjustment, what I initially thought, not to get out. The solution must be sought in the process. The scavenging is also expected as very critical and needs to be improved in some way. And may be some day it will run, with new idees it is not impossible, I'm still working on it.

What do we know at this moment
1. In the 20s of the last century there were already engines with this system,
2. In the 50s there were Russian coxmotortjes model for this system,
3. In 1986 a patent for granted in England, but without a sequel,
4. Rotax has tested it expanded in 1989, without success
5. Frits Overmars has published his idee more than a month after my FST, and still he only has a printed cylinders. While he wrote in his publication: " Luc it is all about who has the first running engine "
6. He called it FOS, but should have called it DOS, because he got the idea from Cees van Dongen in 1969, that's why it took 30 years like he wrote.
7. Ken Seeber 29 July, 2013 wrote he had the idea in 1984, but not 100% TA, read below

And what about those engines in the 20's. That answer is quit simple, those engines are not 100% TA and had no expansion exhaustpipes and therefore only runs in low engine speed with very low power. My prototype that runs after 3 months, had much more speed, but not enough, what it should be. Even without proper exhaust pipes like those Russian glowplug motors it can run for sure. However, in both cases, with much less port surface and therefore also with less engine speed and so very low power is available. What for me was the real reason to start this project.

What actions now?
Seen together it seems that it is never going to work. Does it still feel like there's still time to stabbing? From Frits I have not heard that he is going to stop it, much hurry he did not seem te have, after what is now known. Does it still make sense for me? No and Yes, No, because I do not have the impression that I could do it better than Rotax. Yes because I do have the engine, the cylinder and the exhaust pipes, so why not try something else? I am now 70 and still do not feel to be too old to learn. I'm looking for new idees to solve the current problems. Read below how it all started.


First publication of this new 2 stroke process
website: http://www.geocities.ws/lucfoekema/FSTsystemNL.html


Original text of January 19, 2008

FST a new twostroke scavenging system. About 2 years ago I got the idea to change the way of scavenging of the twostroke engine. The current way of scavenging exist almost from the beginnng of the 2-stroke history and never changed, unless the many other systems which had been founded. But thinking to get more power you automaticly come to new ideas. So to me it came about two years ago, and that is the Foekema Symmetric Twostroke (FST).

It was not my intention to announce this new idea before making and testing it, but I was supprised when reading the magazine of Kickstart of january this year. Frits Overmars also got a new idea, which he called the FOS system. When reading, I thought: "I'm not sure, but it could be the same". Lucky for me he didn't explain the system, otherwise he would be the first. May be it is different, than we will have 2 new systems at almost the same time. The idea is not very difficult, but realising ideas like this is not that easy, because it has to be made very precisely.
Many things in two-stroke tuning has been made since the beginning of the two stroke. That is why I thought that someone else already did the same in the past. Till sofare I didn't want to spend time for this because there are many more important things to do when you wanted to be the fastest 50cc sprinter in the world on the 150 meter and the 1/4 mile.

The only thing I did was an announcement on the Kreidler.nl site, but without an explenation. Also I did tell it to some friends. But because in the current circumstances, I can't wait to explain my new system. That's why I like to introduce you the "Foekema Symmetric Two-stroke" (FST)
Who would be the first realising the idea in a working prototype is another question. Althought this system should produce more power than the current way, it still is the question, if in practice this will be prooven.

FST scavenging
Symmetric is one part to explain the system, but most important is the 100% Time Area. The whole scavenging will proceed in a symmetric way. After burning the gasses, when the piston goes down, the 4 exhaustducts opens first at the same time and the burned gasses leaves the cylinder. These ducts are fully symmetric around in the cylinder, so the gasses can flow into the 4 exhaustpipes very fast. After that, all symmetric transfers opens also at the same time and fresh gasses flows from all directions right over the piston to the center of the cylinder. This result in a flow of the gasses in the direction of the chamber, while pressing the last burned gasses to the edge of the cylinder. In the chamber the fresh gasses will turn around in the direction of the four exhaust ducts, behind the burned gasses.
So two rows of fully symmetric and 100% Time Area ports. The upper 4 ports are exhausts, the lower row are transfers. Which results in much maximum Time Area capacity, which is 100%. There is no more room left for ducts.

Advantage of FST scavenging
The big advantage is that the whole scavenging will proceed much faster than in the current two-stroke way, because of the maximum TA capacity. That is why a much higher rpm is reacheable with the same or even a lower duration of exhausts and transfers.
Beside this there is another great advantage the symmetric scavenging keeps the temperature in the cylinder completely the same all arround. In the current way there are always risks that one side of the cylinder is more hot than the other side.

There is much more to read and to see if you follow the link, which is public, in Dutch and English
https://www.facebook.com/notes/luc-f.../4085704360035
or here website, which is not up to date, because I don't have access anymore: http://www.geocities.ws/lucfoekema/FSTsystemNL.html

The reason to post this is:
1. That the whole story should be known and not some details.
2. I did not work on the system for many years, but this doesn't mean that it stays that way.
3. I got hundreds of ideas from all over the world how to do, but I never saw one which was bright enough to try.


.

[Muhr]

The temperature drop... can this be explained? would it be different if it misfired?

I suppose pipe length to the sensor is devastating for reaction time!?
something more that came to mind was Bernoulli's principle

The faster air moves the lower pressure it has (Bernoulli's principle). So when you blow faster, your stream of air is lower pressure than the surrounding air. Thus the surrounding air fills in the stream. The surrounding air is probably cooler than the exhaust gas.

Just want to clarify that the cooling effect occurs when you release into the atmosphere.

[Haufen]

The reason to post this is:
1. That the whole story should be known and not some details.
2. I did not work on the system for many years, but this doesn't mean that it stays that way.
3. I got hundreds of ideas from all over the world how to do, but I never saw one which was bright enough to try.

1. that is always the best way.
2. I understand, I've got projects like this, too. Most people have, I think.
3. So you would like to discuss and get fresh ideas?

[Pursang]

Re stinger size and pressure.I have measured several engines and found that 2.5psi at full noise seemed to be a constant.
But the process is a bit counter intuitive in that less pressure in the pipe ( ie a big stinger ) renders the pipe less "efficient " at low rpm.
Thus when the return wave comes back to the piston face too early at lower speeds this reduced pressure also reduces the power loss due to the wrongly timed stuffing process.
Increasing the pressure ( a smaller stinger ) makes better power higher up.
This is used in the Jetski world to good effectby having a oversize stinger, and using a rpm controlled solenoid, water is than dumped into it to increase the back pressure at higher engine speeds.
PWM valve control makes it even better.
Easy way to size a stinger ( or nozzle settup ) is to look at the Mach number in the restriction using EngMod, 0.8 Mach works best every time.

What about an undersized stinger/nozzle and a blow-off valve regulating pipe bleed pressure to maintain (say)2.5 psi at all engine speeds?
Often thought about it, never found any reference, anywhere. More bottom end and over-rev without ignition retard.

Cheers, Daryl.

[breezy]

The faster air moves the lower pressure it has (Bernoulli's principle).

Just want to clarify that the cooling effect occurs when you release into the atmosphere.

ok thanks.... just seems weird... as your sampling the gases in the cylinder at a higher rpm, with the heat increasing with more fuel combusting and yet the stream of gas at that sensor hole sending out cooler air just before the exhaust port opens. i would have expected to burn my finger

[lohring]

The FOS system still seems promising. I've run a lot of simulations on EngMod and still get more power with it than Aprilia style porting in a 26 cc disk valve engine. However, EngMod's scavenging model may not give the correct scavenging efficiency. One slightly off topic question: Can you plate a laser sintered cylinder?

Lohring Miller

[SwePatrick]

Does even programs calculate how aircolumn is movin in cylinder?

I think they are only calculating areas vs areas, and how 'much' it flows' etc etc.

The column is very complicated to calculate.

[FastFred]

Thanks Lucf for posting the information here. And thumbs up for your effort in daring to try the unknown in building and testing something new.

Plus One for that, very interesting project.

[wobbly]

Pursang - you have it arse about face.You dont want 2.5 psi at low rpm , less is better.
So a small stinger would need a blow off that dumped pressure at low rpm, then closed off to raise the pressure as speed went up.

And as for anyone asking Luc to produce a dyno graph of his FOS setup, that is like asking Jesus for a sign that he is planning on coming back.

[lucf]

And as for anyone asking Luc to produce a dyno graph of his FOS setup, that is like asking Jesus for a sign that he is planning on coming back.

It seems to me that you have to read it over again !

.

[Grumph]

It seems to me that you have to read it over again !

.

I tend to agree. This system must be looked at quite separately from the Ryger debacle. You've been very frank about what you've seen as the failings of this layout - and at this point I think it is probably a blind alley. But if someone does not at least shine a light up these alleys we'll never know if they're worth pursuing.

From where I'm sitting it looks like both the Bradshaw/Ryger and the FOS type systems have basic faults with scavenging. Pressure pulse or enhanced velocity scavenging seems to clear the cylinder unevenly (Bradshaw's published results). The FOS system with it's multiple exhausts would seem to evacuate the cylinder too well, leading to probable charge loss.
Neither system would seem to develop the rising column of fresh charge shaped to drive out the residual exhaust gases as has been pointed out by SwePatrick.

[lucf]

Maybe it could be a little bit better if aiming all transfers the same way all around to build a swirl upwards in cylinder.

That was 10 years ago the first thing I did, but at that time no result !
This doesn't mean it was a bad idea.