ESE's works engine tuner

[F5 Dave]

I imagine he wants to fit it inside the cases, because, you
know, why make it too easy?:lol:

[wobbly]

That length guide for a 12,000 rpm reed intake tune is the 3rd harmonic.
In that scenario the intake creates a + pressure ratio at the reeds , just as the case goes - from the piston rising.
This tuning opens the reeds very quickly , with + on one side and - on the other.
If tuning near peak Hp the reed setup is limited , just as a RV is limited by the length of available carbs , the rubber manifold , and the reed block or RV cover length.
Everything is being done now to get this length down , for example , by recessing the rubber manifold into the reed stuffer.

[Flettner]

Or just throw the carburetor / throttle body away.

[andreas]

Vacuum operated gibs?? why are they called gibs?

[Muhr]

Vacuum operated gibs?? why are they called gibs?

I think in this case one refers to a T-shaped linear slide bearing which is usually called Gib.
But of course I hope it refers to Josiah Willard Gibbs Quote:
"The greatest amount of mechanical work which can be obtained from a given quantity of a certain substance in a given initial state, without increasing its total volume or allowing heat to pass to or from external bodies, except such as at the close of the processes are left in their initial condition.

[andreas]

I think in this case one refers to a T-shaped linear slide bearing which is usually called Gib.
But of course I hope it refers to Josiah Willard Gibbs Quote:
"The greatest amount of mechanical work which can be obtained from a given quantity of a certain substance in a given initial state, without increasing its total volume or allowing heat to pass to or from external bodies, except such as at the close of the processes are left in their initial condition.

Aha, I bet this was when he, Maxwell and the Invisible friend was trying to trick entropy?

[Flettner]

Vacuum operated gibs?? why are they called gibs?
???
Not sure if you are pulling my leg or not.
The single sided Sliding Gib could be operated via vacuum or as I did with a sevo run off the Ignitech. Separate throttle body.
The two sided Slding Gib can not as it now becomes the throttle body as well. In the interests of just getting my 360 up and running Ive just connected the Gibs direct to the twist grip. Ultimately these Gibs should be controlled via the ecu. You tell the ecu what you want (twist grip) and it juggles the Gibs to suit.

[andreas]

???
Not sure if you are pulling my leg or not.
The single sided Sliding Gib could be operated via vacuum or as I did with a sevo run off the Ignitech. Separate throttle body.
The two sided Slding Gib can not as it now becomes the throttle body as well. In the interests of just getting my 360 up and running Ive just connected the Gibs direct to the twist grip. Ultimately these Gibs should be controlled via the ecu. You tell the ecu what you want (twist grip) and it juggles the Gibs to suit.

No, I only thought that if the gibs are also the throttle it would be nice if there was an rpm function to the opening. But I didn't know how it worked.

[TZ350]

Vacuum operated gibs?? why are they called gibs?

348756

"gib" is a name for a style of captive sliding device.

[andreas]

Thanks TZ.

[Flettner]

Thanks TZ.

Andreas, a curved sliding Gib, seen here fully in the fully open position.

[andreas]

Andreas, a curved sliding Gib, seen here fully in the fully open position.

It really is an excellent invention.

[F5 Dave]

And still nothing to do with the BeeGees .

[husaberg]

???
Not sure if you are pulling my leg or not.
The single sided Sliding Gib could be operated via vacuum or as I did with a sevo run off the Ignitech. Separate throttle body.
The two sided Slding Gib can not as it now becomes the throttle body as well. In the interests of just getting my 360 up and running Ive just connected the Gibs direct to the twist grip. Ultimately these Gibs should be controlled via the ecu. You tell the ecu what you want (twist grip) and it juggles the Gibs to suit.

Neat so with it fly by wire from the ECu you can then have traction control, or idiot control,wheelie control wet slippery etc right down to gps of parts of the tracks.
if anyone is in doubt of the validity of this drive a late model manual in power ,eco mode etc
its not the power output of the engine that generally changes, its the throttle response to the inputs that do.
In most instances it just opens the throttle further for the same accelerator input.
As a team owner You could also use it to make your number 2 driver slower.

[Flettner]

Neat so with it fly by wire from the ECu you can then have traction control, or idiot control,wheelie control wet slippery etc right down to gps of parts of the tracks.
if anyone is in doubt of the validity of this drive a late model manual in power ,eco mode etc
its not the power output of the engine that generally changes, its the throttle response to the inputs that do.
In most instances it just opens the throttle further for the same accelerator input.
As a team owner You could also use it to make your number 2 driver slower.

Might even help silly old bustard's like me be a little more competitive again, i.e. not so slow on a trail ride.
The ecu throttle with sliding gibs is more useful because there is a difference between throttle opening and gibs valve timing. At the moment the opening timing is just set via the small tooth belt pully tooth numbers.
Its a cool piece of technology, so long as Im the only one entered in the event with it:msn-wink:
https://youtu.be/bhKrRlZxomc

[Muhr]

Aha, I bet this was when he, Maxwell and the Invisible friend was trying to trick entropy?

I suspect that it is your chess interest that shines through. Have never played myself but have heard of some theory that is derived from thermodynamics


Might even help silly old bustard's like me be a little more competitive again, i.e. not so slow on a trail ride.
The ecu throttle with sliding gibs is more useful because there is a difference between throttle opening and gibs valve timing. At the moment the opening timing is just set via the small tooth belt pully tooth numbers.
Its a cool piece of technology, so long as Im the only one entered in the event with it:msn-wink:
https://youtu.be/bhKrRlZxomc

It is great to be able to use it for both port duration adjustment and throttle by running drive by wire. What type of motors do you use, is there a type of stepper to get sufficient accuracy?

[ceci]

Neat so with it fly by wire from the ECu you can then have traction control, or idiot control,wheelie control wet slippery etc right down to gps of parts of the tracks.
if anyone is in doubt of the validity of this drive a late model manual in power ,eco mode etc
its not the power output of the engine that generally changes, its the throttle response to the inputs that do.
In most instances it just opens the throttle further for the same accelerator input.
As a team owner You could also use it to make your number 2 driver slower.


That story of harming other drivers through electronics sounds like an Aprilia 250cc test driver, who only won one grand prix at the world championship (he was the one who tuned the electronics and he knew what was going on)

[Frits Overmars]

That story of harming other drivers through electronics sounds like an Aprilia 250cc test driver, who only won one grand prix at the world championship (he was the one who tuned the electronics and he knew what was going on)Are you talking about Marcellino Lucchi? He was 'the' Aprilia test rider. In fact Lucchi was only a part-time test rider; in the mornings he was the driver of the local garbage truck; in the afternoons he rode a little faster. I remember him lapping the Jerez Grand Prix track on an Aprilia-250 faster than Max Biaggi on a works Honda 500-4, much to the malicious pleasure of the Aprilia mechanics who had have to work with Biaggi in previous years when Max was riding the works Aprilia-250.
Lucchi was not a regular GP participant; enrolling him for one or two GPs a year was Aprilia's way of thanking him for his efforts. He was a great character and certainly not one to disadvantage other riders.
348761

[ceci]

Are you talking about Marcellino Lucchi? He was 'the' Aprilia test rider. In fact Lucchi was only a part-time test rider; in the mornings he was the driver of the local garbage truck; in the afternoons he rode a little faster. I remember him lapping the Jerez Grand Prix track on an Aprilia-250 faster than Max Biaggi on a works Honda 500-4, much to the malicious pleasure of the Aprilia mechanics who had have to work with Biaggi in previous years when Max was riding the works Aprilia-250.
Lucchi was not a regular GP participant; enrolling him for one or two GPs a year was Aprilia's way of thanking him for his efforts. He was a great character and certainly not one to disadvantage other riders.
348761


Hi Frits.
I'm talking about Álex Debon, test pilot, for two years,

https://www.motogp.com/en/news/2005/11/16/debon-lands-testing-role-with-aprilia/139699

He was the one who did the ECU settings for the RSA250.
What he should know is that others were winning with worse times around curves and laps than the ones he had registered in the testing phase (in competition he didn't get them either, his times being even higher than those of the winners. )

[ken seeber]

2 STROKE LUBRICATION

Currently there are 4 commonly known methods of achieving this:
1. Oil in fuel
2. ECU controlled electronic pump, eg Mikuni.
3. Yamaha Autolube / Suzuki Posiforce mechanical pumps
4. OMC VRO
5. Any more?

Another passive way might be the use of the Marvel Inverse Oiler. As its name implies, it relies on vacuum to draw a flow of oil into the inlet manifold, the flow rate increasing as the vacuum diminishes, ie going to a higher load.

Any thoughts on whether it has ever been used (successfully) on a 2 stroke?


348764348765348766

[husaberg]

2 STROKE LUBRICATION

Currently there are 4 commonly known methods of achieving this:
1. Oil in fuel
2. ECU controlled electronic pump, eg Mikuni.
3. Yamaha Autolube / Suzuki Posiforce mechanical pumps
4. OMC VRO
5. Any more?

Another passive way might be the use of the Marvel Inverse Oiler. As its name implies, it relies on vacuum to draw a flow of oil into the inlet manifold, the flow rate increasing as the vacuum diminishes, ie going to a higher load.

Any thoughts on whether it has ever been used (successfully) on a 2 stroke?


348764348765348766

from memory both early Villiers and i think the GTP Velocette had some sort of vacuum oiling system.
Grumph will know he was around then:bleh:

https://lh3.googleusercontent.com/proxy/QmOBzzeCxgbfguQUlRvI0CeuYLlyb8ltvItAhqnm0sswPVH_Ur naX-l1UFM0jgOQsw3YHvmdKs2TB1cbZkYvozCzvVDRhfhnef50Ym0
https://oldtimermoto.nl/wp-content/uploads/2016/02/villiersstory.pdf

https://www.bike-urious.com/1938-velocette-gtp/

[OopsClunkThud]

2 STROKE LUBRICATION

Currently there are 4 commonly known methods of achieving this:
1. Oil in fuel
2. ECU controlled electronic pump, eg Mikuni.
3. Yamaha Autolube / Suzuki Posiforce mechanical pumps
4. OMC VRO
5. Any more?

Another passive way might be the use of the Marvel Inverse Oiler. As its name implies, it relies on vacuum to draw a flow of oil into the inlet manifold, the flow rate increasing as the vacuum diminishes, ie going to a higher load.

Any thoughts on whether it has ever been used (successfully) on a 2 stroke?



Vespa has used a mechanical pump that injects the oil to the carb, just below the slide. The cases have a boss for injecting to the flywheel side main bearing, but as far as I know they never used that in production. there have been a few different pump designs but all deliver increased volume per revolution with increased throttle position.

[ceci]

Hi Frits.
I'm talking about Álex Debon, test pilot, for two years,

https://www.motogp.com/en/news/2005/11/16/debon-lands-testing-role-with-aprilia/139699

He was the one who did the ECU settings for the RSA250.
What he should know is that others were winning with worse times around curves and laps than the ones he had registered in the testing phase (in competition he didn't get them either, his times being even higher than those of the winners. )



What I am suggesting is that having a large fan club and merchandising, in addition to other interests, can influence.

[TZ350]

.
2021 Tokoroa F4 GP.
.
<iframe width="560" height="315" src="https://www.youtube.com/embed/XYuYBpvLp00" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Two warm up laps then the start.

Team ESE's Blair Lambarth on an ESE 110cc Suzuki GP100 powered Team GPR rolling chassis had been fastest all weekend and was on pole position for the GP. But unfortunately crashed out spectacularly on the second lap.

Kieren eventually took the win on a Team GPR bike followed by Paul Ellis (the Bike with the camera) riding his very trick Yamaha powered home built special and Regan Griffiths on another Team GPR bike came in third.

I rode in the F5 GP, and finished last. It was a great weekend. Friendly people, great weather and racing. Loved it.

[ken seeber]

Vespa has used a mechanical pump that injects the oil to the carb, just below the slide. The cases have a boss for injecting to the flywheel side main bearing, but as far as I know they never used that in production. there have been a few different pump designs but all deliver increased volume per revolution with increased throttle position.

Patrick, thanks for that. One obvious downfall of the simple inverse oiler is that it is independent of engine power & speed, unlike fuel oil mix which is essentially proportional to power. Perhaps this shortcoming could be addressed by having a pitot tube in the throttle body, this measuring the air flow. Such a pressure signal could activate some secondary diaphragm in the device to provide some relationship between oil flow and power.

[yatasaki]

I would need ESE thread approval for this chainsaw reed stuffer.

[Peter1962]

Forced lubrication has been used by BRP on their 850 E-tec, and also on the Evinrude outboard two strokes. This method of lubricating the crankshaft bearings, the bigend, could be combinated with the standard lubrication on the KTM TPI, or need I say : the Fletner TPI. And that is where the market in 2021 is : ktm are selling more two strokes then 4 stroke enduro engines.
https://www.youtube.com/watch?v=Jj_lkGjgwR8&t=18s

edit : for better quality pictures, and some interesting schematics, please go to posting number 55 on this thread : https://www.dootalk.com/forums/topic/1573975-pre-mix-in-tank/page-4

[Flettner]

As I said earlier my oil feed system is a little different with the the autolube oil being delivered through a hollow crankshaft but transported by airflow.
Air is continuously being drawn through this hollow shaft and out through the bigend pin into bearing. Drilled with a carbide bit.
The idea being, as the engine loads, power valve opens, this opens the crank driven autolube. Oil is intantly feed into the small continuous airstream through the crankshaft. Oil is deposited at the bigend roller bearing almost instantaneously.
Thats the idea for what its worth, my 360 bigend hasn't seized yet, I guess its working.

[Flettner]

I just installed a small battery on to the 360, might have some independence from the dyno this weekend. Im going to just have to get used to this jolly left boot kick start. Designed way back when I had a rooted right hip. It will be interesting to see how it runs round the back yard.
This would have to be a first, dual sliding gib throttle / mk2 TPI, operating under its own Steam i.e. not tied to a dyno.

[TZ350]

.
More from the Two Stroke Stuffing workshop.
.
<iframe width="560" height="315" src="https://www.youtube.com/embed/IGuF1Uwupcs" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

[ceci]

2 STROKE LUBRICATION

Currently there are 4 commonly known methods of achieving this:
1. Oil in fuel
2. ECU controlled electronic pump, eg Mikuni.
3. Yamaha Autolube / Suzuki Posiforce mechanical pumps
4. OMC VRO
5. Any more?

Another passive way might be the use of the Marvel Inverse Oiler. As its name implies, it relies on vacuum to draw a flow of oil into the inlet manifold, the flow rate increasing as the vacuum diminishes, ie going to a higher load.

Any thoughts on whether it has ever been used (successfully) on a 2 stroke?


348764348765348766


https://patents.google.com/patent/US4411225?oq=inassignee:%22Dell%27orto+S.P.A.%22


https://patentimages.storage.googleapis.com/82/02/36/48a7f0b70ab21e/US4411225-drawings-page-2.png

[lohring]

Has anyone tried this?

https://www.youtube.com/watch?v=xiI_g08H5RY&t=284s

Lohring Miller

[Flettner]

Ready to test.

[Flettner]

It goes under its own power, ripping around the yard.
All good until the chain came off, forgot to put the clip on. Couldn't find the pliers in my haste, I'll do it later I thought, I didnt.
Superficial damage only thankfully. But it runs and reasonably well.

[TZ350]

It goes under its own power, ripping around the yard.....it runs and reasonably well.

...Very Impressed ................it lives.........:wings:

[F5 Dave]

Haha. Inspirational genius foiled by human distraction and impatience. Glad it's not only me. Minus the genius part of course. :rolleyes:

[Muhr]

2 stroke drag racing


https://m.youtube.com/watch?v=eRItqiCFuQE

[RomeuPT]

Hello

Long time, no posting.

Been doing my exhaust's, mostly stainless 304, 1mm

Does anybody have any hacks or tools for getting joint's more acurate without just hamering them? Or even to make the headers round in any other way then a regular hammer?

Arm and moslty Elbow starting to complain seriously... not strong armed :/

I think I already explored my hammer technic wheel and its only with about 450g hammer's but still...

Maybe I should create an electric hammer to beat the header welds or just train the left harm :crazy:?!

Really looking into improving efficiency.

Cheers

[lodgernz]

Hello
Long time, no posting.
Been doing my exhaust's, mostly stainless 304, 1mm
Does anybody have any hacks or tools for getting joint's more acurate without just hamering them? Or even to make the headers round in any other way then a regular hammer?
Arm and moslty Elbow starting to complain seriously... not strong armed :/
I think I already explored my hammer technic wheel and its only with about 450g hammer's but still...
Maybe I should create an electric hammer to beat the header welds or just train the left harm :crazy:?!
Really looking into improving efficiency.
Cheers

Have you tried making the headers by hydroforming?
Avoids multiple welds with potential notches and unplanned section changes.

[wobbly]

I have to ask , why are you using 1mm - I have tested this twice now on completely different engines.
0.8 makes better power.
1mm in SS would be a nightmare to hammer , as you have found.
But if the cuts are shallow enough , and with well purged welds you dont need to hammer them - in this case , no power lost.

Edit - added a un hamered pipe pic

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/-ocIH8rBdJ8" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Where it starts ........

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/-tEeHq8fdq0" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/1dStzgUqv-c" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/r8ocwPRVu-0" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Where it is now....:niceone:

https://youtu.be/4Uv2_0n7NJY

[katinas]

Hello

Long time, no posting.

Been doing my exhaust's, mostly stainless 304, 1mm

Does anybody have any hacks or tools for getting joint's more acurate without just hamering them? Or even to make the headers round in any other way then a regular hammer?

Arm and moslty Elbow starting to complain seriously... not strong armed :/

I think I already explored my hammer technic wheel and its only with about 450g hammer's but still...

Maybe I should create an electric hammer to beat the header welds or just train the left harm :crazy:?!

Really looking into improving efficiency.

Cheers

Hi Romeu, for header section easiest way to use stainless steel 1 mm thick elbows, just cut out them at inside radius, similar to triangle shape, deform, weld and you get conical elbow.
Like Wob said, long time ago racers discovered that for diffuser, belly and baffle sections, thicker than 0.75 mm and power started to drop.

https://www.ebay.co.uk/itm/2-5-63mm-Stainless-Steel-90-Degree-Car-Exhaust-Elbow-Pipe-Welding-Bent-Joint/112750423829

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/woB5Ht-Zuk0" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

[ken seeber]

Was looking up info on air brake dynos and remembered this article in my scrapbook. It is readable, but you might have to persevere a tad.

So interesting is the fact that it is 40 years old and old mate, Barry Hart, is on about things that are still being discussed today.

http://yorkshireferret.blogspot.com/2012/02/barton-motors-sparton-phoenix-and-more.html

348786348787

[husaberg]

Was looking up info on air brake dynos and remembered this article in my scrapbook. It is readable, but you might have to persevere a tad.

So interesting is the fact that it is 40 years old and old mate, Barry Hart, is on about things that are still being discussed today.

http://yorkshireferret.blogspot.com/2012/02/barton-motors-sparton-phoenix-and-more.html

348786348787

Herbert Munro
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130432948&highlight=paddle#post1130432948

348788348789348790348791348792

[RomeuPT]

I have to ask , why are you using 1mm - I have tested this twice now on completely different engines.
0.8 makes better power.
1mm in SS would be a nightmare to hammer , as you have found.
But if the cuts are shallow enough , and with well purged welds you dont need to hammer them - in this case , no power lost.

Edit - added a un hamered pipe pic

Thanks for all answers

I am using 1mm because it's for decent lasting exhaust's. 0,8 cant stand long on engines with shittie ton of vibration that some ignore has normal, then even with 1mm I have occasional header welds cracked which is bad for feedback. Also welds easier.

It's not hard to hammer, its just that I have done alot over the years and its getting heavy.

In some cases 20€ is enought to lose a sell to others, so It wont pay a decent spring adapter either.

The pipes are not for racing but for weekend road use, fun... poeple like to see the header welds and it helps selling.

Looking for tools to keep doing my job not to change the product, but thanks anyway :)

348793348794348795

[Mike Fisher]

Was looking up info on air brake dynos and remembered this article in my scrapbook. It is readable, but you might have to persevere a tad.

So interesting is the fact that it is 40 years old and old mate, Barry Hart, is on about things that are still being discussed today.

http://yorkshireferret.blogspot.com/2012/02/barton-motors-sparton-phoenix-and-more.html

348786348787

Barry Hart has published a book 'Pursuit of Dreams' and an e-book technical supplement that starts with 'How to Win Races' then includes Producing gear change selector drums, Producing crankshafts, Aligning crankshaft gears, Tuning Engines & dyno Testing, Basic Tuning theory , The importance of Torque, Variable true compression pressure Engines (VCE), Specific Time Areas, Twin Firing Order, Power Valves, Exhaust Power Valves, Inlet power valves, etc. available from https://www.pursuitofdreams.co.uk

[Pursang]

Ok!...Burt was able to load nearly 100 bhp with 2 plywood paddles of 8" x 14" rotating at 2000rpm.:eek5:

If one had access to a machinery salvage site and could obtain something like this it might allow a safer setup.
https://www.machineryandequipment.com/pub/media/catalog/product/s/7/s738903_3_.jpg


Rated at 100bhp for mine ventilation, grain drying, lots of uses.

Redirect the outlet for engine cooling.

Cheers, Daryl.

[Larry Wiechman]

Dobeck air dyno.http://www.axisdyno.com/

[OopsClunkThud]

CFD of the exhaust has turned into quite the rabbit hole.

The results on simscale were showing the adding side wall angle was almost always helpful, but kind of all over the map in trying to find "the best" angle. Started looking at 2D simulation of the port roof and piston crown first and have the first insight that I think is useful.

The flow is sonic for most or all of the blowdown. There is clearly separation at the port roof but to keep the same timing any radius there will have to impose on the flow (same at the side wall). That is likely worth it, still need to check that out. But to speed up the flow before it gets to the port needs something inside the cylinder, like a radius on the edge of the piston maybe... At sonic speeds it does not take much of a chamfer to create an expansion fan. This test has a chamfer that is 2mm in from the edge of the piston and angled down only 10° from the tangent line of the piston crown. This lowers the timing edge of the piston by .4mm, far less than a full radius. I was expecting to see two things:

1. The point where the flow goes sonic moves inward from the timing edge of the piston to the edge of the chamfer (result: Yup)
2. The mass flow rate across the port face increases (result: ~5% increase)

348799

The image on the left has a normal domed top piston and the flow goes sonic at the timing edge. Image on the right has a shallow chamfer on the edge of the piston and the flow goes sonic sooner, at the start of the chamfer, while it’s still inside the cylinder.

One other observation is that depending on the shaping of the port walls you can end up with shock diamonds (wasting a lot of the exhaust energy) or a single shock when it drops back to subsonic.

[wobbly]

The CFD results sure are interesting. And looking at EngMod results for the RSA at 13,000 , yes the port face is sonic almost till TPO.
What I have wondered about is the results I have got from two tests.
First was a piston comparison. Normal 4* conical Vs a flat top with a 1mm radius .The flat top was 0.5mm taller so the effective EPO/TPO was the same.
The result , with identical compression and squish , was a good gain to the radius piston up the front side to peak , but an even bigger loss in overev power.
It would be interesting to see what effect the radius has on boost port flow , as it has been reported here that deleting the radius over the boost , and adjusting the timing back to original
gave an increase in power everywhere.
This I have not had time to do as of yet.
My take on it is that the radius over the boost pulls the boost port flow that has stayed attached to the piston , down toward the Exhaust port , instead of up the rear wall.
Be interesting to see what CFD shows in this area.

[andreas]

CFD of the exhaust has turned into quite the rabbit hole.

The results on simscale were showing the adding side wall angle was almost always helpful, but kind of all over the map in trying to find "the best" angle. Started looking at 2D simulation of the port roof and piston crown first and have the first insight that I think is useful.

The flow is sonic for most or all of the blowdown. There is clearly separation at the port roof but to keep the same timing any radius there will have to impose on the flow (same at the side wall). That is likely worth it, still need to check that out. But to speed up the flow before it gets to the port needs something inside the cylinder, like a radius on the edge of the piston maybe... At sonic speeds it does not take much of a chamfer to create an expansion fan. This test has a chamfer that is 2mm in from the edge of the piston and angled down only 10° from the tangent line of the piston crown. This lowers the timing edge of the piston by .4mm, far less than a full radius. I was expecting to see two things:

1. The point where the flow goes sonic moves inward from the timing edge of the piston to the edge of the chamfer (result: Yup)
2. The mass flow rate across the port face increases (result: ~5% increase)

348799

The image on the left has a normal domed top piston and the flow goes sonic at the timing edge. Image on the right has a shallow chamfer on the edge of the piston and the flow goes sonic sooner, at the start of the chamfer, while it’s still inside the cylinder.

One other observation is that depending on the shaping of the port walls you can end up with shock diamonds (wasting a lot of the exhaust energy) or a single shock when it drops back to subsonic.

Excuse the ignorance, but what is, and what is the cause of shock diamonds? Nevermind I just remembered where they explain stuff. But for sure is interesting.

[OopsClunkThud]

...what is, and what is the cause of shock diamonds?

It's a pattern that forms in a supersonic flow that has expanded and dropped to a pressure of its surroundings. Mostly seen in rockets and afterburners, the gas passes through a shock wave that brings it subsonic, then passes through an expansion fan and goes super sonic, creating the pattern. It's not like we want the exhaust to be a rocket (I don't think we do) but we do want to conserve the energy as a pressure wave and not just heat. So if it's not too hard to prevent them I think it may be worth doing.

Wind tunnels have lots of tricks to prevent them, and a taper in the exhaust stub looks a lot like some of those tricks.

https://en.wikipedia.org/wiki/Shock_diamond

Much of this is beyond my pay grade, but rabbit holes... oh and sonic flow is weird

[Muhr]

An explanation for us mortals.

http://franciscoalario.aero/shock-diamonds/

The question is whether this happens to any great extent what is the pressure difference vs velosity?

"They are triggered by the gas pressure at the exit of the engine bell being higher than the surrounding air pressure"

"The mass flow rate for a compressible fluid will increase with increased upstream pressure, which will increase the density of the fluid through the constriction (though the velocity will remain constant). This is the principle of operation of a Laval nozzle. Increasing source temperature will also increase the local sonic velocity, thus allowing for increased mass flow rate but only if the nozzle area is also increased to compensate for the resulting decrease in density."

https://digital.library.adelaide.edu.au/dspace/bitstream/2440/20904/2/02whole.pdf

[ceci]

Upon discovering this patent.

https://patents.google.com/patent/US3289656A/en?oq=US3289656A

The title or name of it made me think about this:


And adding to the effect of having very high exhaust duration you can cut the skirts short such that the port is open a few mm when the piston is at TDC.
Wreaks havoc with the jetting , but in the project i tried that we were using big pumper carbs.
Very easy to adjust the fuel curve as was needed - but I doubt a normal carb could be made to work.
This setup on a " stock " 950 SeaDoo gave an added 8 Hp in about 80 , so 10% - enough for the title at Havasu.
On a 1180 twin race motor the bump was 15 Hp in 120 so a little less.

that is precisely because of this word "crossfeed"

There are structural differences between this and Wobbly's and it may be that in these differences this is the key to success, wobbly if it has shown the increase in power.

Does anyone know if in motoGP 500 and motoGP 250 if they investigated with something similar.
With the multitude of projects that people do multi-cylinder, nobody works on anything like that

[OopsClunkThud]

The CFD results sure are interesting. And looking at EngMod results for the RSA at 13,000 , yes the port face is sonic almost till TPO.
What I have wondered about is the results I have got from two tests.
First was a piston comparison. Normal 4* conical Vs a flat top with a 1mm radius .The flat top was 0.5mm taller so the effective EPO/TPO was the same.
The result , with identical compression and squish , was a good gain to the radius piston up the front side to peak , but an even bigger loss in overev power.
It would be interesting to see what effect the radius has on boost port flow , as it has been reported here that deleting the radius over the boost , and adjusting the timing back to original
gave an increase in power everywhere.
This I have not had time to do as of yet.
My take on it is that the radius over the boost pulls the boost port flow that has stayed attached to the piston , down toward the Exhaust port , instead of up the rear wall.
Be interesting to see what CFD shows in this area.

for the "Normal 4* conical" did that have a flat in the center? if so did the flat extend to the edge of the squish?

[wobbly]

In the radius tests I did the normal 4* conical did not have a flat top.
That design came later as one of the planned updates for the R1 engine.

I tested first the flat top extending right out to the squish edge of the chamber , but in the KZ engines the SAR is only about 34% due to the straight line ignition curve.
Next I made the flat top 50% of the piston area , this combined with lowering the plug/roof as much as possible within the cc constraints , made easily the best power.

For some reason beyond my grasp of Italian tech talk , the factory combined my proven flat top design , with a new piston skirt having a big cutout above the pin to reduce weight.
This almost halves the power gain , given by simply taking the older model light weight design with a 0.8 ring and machining 1.2mm off the conical dome.
That trick proved the dome was too thick to start with , and ends up being much lighter than the new Vertex effort.

[Hoebra]

@Frits Overmars, how is it possible to get some of the Piston Pin Plugs you showed here many times in 12mm version?

[ceci]

https://www.youtube.com/watch?v=qk-OIltQAYE

[OopsClunkThud]

results: The flat top piston with 1mm radius at the edge flows less exhaust than the 4° conical. When the port is open only 5° the radius flows 10% less, and just before the transfers open it's only 2% less. Looking at the images it's clear that relative to the conical piston the radius is shrouding the flow and reducing the area. The radius also does not add much to the ability of the gas to turn the corner at the edge of the piston. At sonic speeds this is driven by the heat and pressure of the gas. If there is enough heat and pressure (as when the port first opens) the gas can turn ~20° around the edge of the piston, and if there is not enough (at the end of blowdown) then the flow separates from the radius.

348825348826

I did some quick tests with a larger radius (keeping the .5mm flat height above the timing edge) and it flowed as well as the conical at the end of blowdown. I'm building out a larger test plan to zero in on an optimal value.

[wobbly]

So I wonder if up the front side the transfer flow Cd effect is greater on power output than the downside of the Exhuast flow Cd.
But in the overev area , the effects reverse efficacy.
Interesting that Jan had to radius the port timing edge to regain lost power in the Aprilia , but a radius on the piston has a negative effect as shown in CFD.

[Frits Overmars]

@Frits Overmars, how is it possible to get some of the Piston Pin Plugs you showed here many times in 12mm version?It was never my intention to start a business with the plugs, which is why I posted both the drawings and the choice of material here, so that anyone who is interested can make them himself or have them made. They are quite simple really.


Interesting that Jan had to radius the port timing edge to regain lost power in the Aprilia , but a radius on the piston has a negative effect as shown in CFD.In the above pictures the piston edge is flush with the exhaust floor. I would like to see the effect of a radiused edge at the onset of blowdown.
I'd also like to see the effect of the radius on the flow from the transfer ducts and the exhaust duct into the cylinder, and the effect it has on piston cooling.

[OopsClunkThud]

In the above pictures the piston edge is flush with the exhaust floor. I'd rather like to see the effect of a radiused edge at the onset of blowdown.
I'd also like to see the effect of the radius on the flow from the transfer ducts and the exhaust duct into the cylinder, and the effect it has on piston cooling.

Frits,

both pictures are at the same same level of zoom, but the exhaust floor is well below the frame of the view. as this is a simple 2D profile, the piston and top of the port/cylinder are all in gray. The subsonic flow in blue and supersonic flow in red.

the first picture is 5° into blowdown, and the second is right at the end of blowdown. Reversing the exhaust is easy enough, I'll pull the pressure values from engmod, the rest of the model is the same (input flow vector is odd, but not hard).

As for the transfers, I'll get to it.

I'm thinking snapshots at 5° increments should be enough, with maybe an extra at 1-2° after EPO.

[Flettner]

Thankyou, thats worthwhile and intetesting work.

[Vannik]

The subsonic flow in blue and supersonic flow in red.


This makes me doubt the software as there is nothing there that can cause supersonic flow, and sonic flow will form a shock and jump back to subsonic. The pressure ratio and duct shape required for supersonic flow does not exist in an engine.

[Muhr]

Sometimes you can be fooled by which wall condition you use, maybe so that you use a slip?
I have been there myself a few times

I had thought to see something similar to below. but I do not have access to so much data power on my simple variant

A little more interesting reading

https://www.e3s-conferences.org/articles/e3sconf/pdf/2020/57/e3sconf_ati2020_06005.pdf

[OopsClunkThud]

I'll be the first to admit that with regards to CFD (and many other topics) I'm no expert. I've been trying to square the "no supersonic" bits of Blair's book with what I was seeing in the 3D CFD on simscale. That's part of what drove me to try some simplified 2D running in SU2. I also very much appreciate the input and help, even (or especially) when I have it wrong.

I was thinking that since the flow is choked, the only way to increase the mass flow rate was to change Cd or A. To decompose the problem, I was looking at the side slice of the 2D flow to see what could be done to improve Cd*A would inform how to shape the port roof and piston, while a top view 2D slice of the side wall angle would inform, well the side wall. Then I could put those back into a 3D and see how it works out.

In both 3D and 2D the walls were modeled as no-slip, but for 2D I made the walls adiabatic. This was all steady state, so that's a known difference from reality.

[Vannik]

Supersonic flow requires a different solving methodology as the waves move in one direction only, as the medium (gas) moves faster than the speed of sound the "rearwards" wave also moves forward because its speed rearwards is less than the gas flow speed. If the numerical method does not do this transition you can get wrong results.

There has been a number of PhD theses in the last few years on the Cd value during sonic flow, it is no longer assumed to be constant. This is very important to 2T engines as the blowdown phase is mostly sonic flow. This is a good area to focus on in my opinion.

[jamathi]

So I wonder if up the front side the transfer flow Cd effect is greater on power output than the downside of the Exhuast flow Cd.
But in the overev area , the effects reverse efficacy.
Interesting that Jan had to radius the port timing edge to regain lost power in the Aprilia , but a radius on the piston has a negative effect as shown in CFD.

Our boss made a new pipe.
It had MUCH better power at intermediate revs.
But the engine did not want to rev anymore.
So I tried to radius the exhaust port:
Max revs got back, same as before
And the power at intermediate revs was the same as with the old pipe......
Nothing gained and nothing lost....
But he could not sell the new pipes to the various teams!!!
Al new cylinders were radiused after this.
So he could sell a new pipe with each new cylinder.
Selling pipes and pistons was a very profitable business.
There were 'light' and 'heavy' pistons.
The light ones had to be changed after each practice, or you would lose a lot of power.
With the heavy ones you could do all practices and the race....
So using light pistons was highly recommended!!!!

[Vannik]

Selling pipes and pistons was a very profitable business.
There were 'light' and 'heavy' pistons.
The light ones had to be changed after each practice, or you would lose a lot of power.
With the heavy ones you could do all practices and the race....
So using light pistons was highly recommended!!!!

We once shared a pit with an Aprillia factory supported team and it was the first time in my life where I saw them removing pistons after each session and checking the dome height in a special jig. Depending on the amount of collapse of the dome they would either bin it or use it with a different head in the next session. Factory support meant they could buy the special stuff, not getting them free.

[wobbly]

Amazing really - if you had not found the solution Jan then the Great Leaders new pipe would have been exposed as being what it was , a flop.
But in the end he came out smelling of Roses as a ton of cylinders and pipes and pistons got sold , and certainly not because he was a clever tuner.

[jamathi]

We once shared a pit with an Aprillia factory supported team and it was the first time in my life where I saw them removing pistons after each session and checking the dome height in a special jig. Depending on the amount of collapse of the dome they would either bin it or use it with a different head in the next session. Factory support meant they could buy the special stuff, not getting them free.

No, nothing for free
On the pistons they had a gain margin of 80%...

[jacobson_se]

Jan did you see any improvments in laptimes with the light pistons?

[F5 Dave]

Did the finance team see an improvement of the lapdancers with an 80% margin? That's fleecing it.

[jamathi]

Jan did you see any improvments in laptimes with the light pistons?

We never tested this difference on a track (as far as I know)
On the dyno there was no difference at all..
I do not see a very light piston as an advantage.
Except vibrations of course!
The difference was 20 grams if I remember well.
The 'light' piston lost power after some 5 dyno runs.
The 'heavy' piston still gave the same power after 30 dyno runs.
And a cast piston was better than a forged one.
But there was no big difference, maybe only 0,2HP

[Muhr]

In both 3D and 2D the walls were modeled as no-slip, but for 2D I made the walls adiabatic. This was all steady state, so that's a known difference from reality.

Hi something that came to my mind. What model do you use for turbulence

https://www.simscale.com/projects/muhr/test_radie-stinger/


An interesting thing is that carbon dioxide has a speed of sound at 267 ms at 20c. do not know if it is right to use it but air also feels wrong.

300 g exhaust gases. The composition is:
180 g of carbon dioxide
70 g water vapor
50 g of other substances (= 36.0 g of carbon monoxide, 9.5 g of hydrocarbon, 3.0 g of nitrogen oxide, 0.25 g of sulfur dioxide, 0.25 g of soot, 0.001 g of lead, 0.0006 g of aldehydes, 0.00025 g organic acids, 0.00025 g ammonia, small amounts of bensopyren.

[OopsClunkThud]

Hi something that came to my mind. What model do you use for turbulence

https://www.simscale.com/projects/muhr/test_radie-stinger/

I'm using SST in both the 3D and 2D. I used air as the fluid, that's another refinement I need to make.

Here's a link to the simscale 3D: https://www.simscale.com/projects/OopsClunkThud/tutorial_2-_pipe_junction_flow/
I set the walls as no-slip, constant temp, and matched the cylinder, piston crown, exhaust header... to the values in engmod
The input pressure and temp were matched to the engmod at the respective crank positions as well.

In the 2D I'm trying to configure things as close as I can to the 3D (SU2 is not as intuitive as simscale)

[Muhr]

I'm using SST in both the 3D and 2D. I used air as the fluid, that's another refinement I need to make.Here's a link to the simscale 3D: https://www.simscale.com/projects/OopsClunkThud/tutorial_2-_pipe_junction_flow/
I set the walls as no-slip, constant temp, and matched the cylinder, piston crown, exhaust header... to the values in engmod
The input pressure and temp were matched to the engmod at the respective crank positions as well.


Nice! I chose to put a reduction instead of a back pressure and that I have a lower temp (it behaves a little strange when you only have one medium).

Here is a simulation with an end time of 0.0002 s

[ceci]

Sorry, I am very insistent but I think that here there are possibilities that the performance of the 2S engine will be improvedhttps://patentimages.storage.googleapis.com/4d/77/de/55f036e5833e93/US3289656-drawings-page-1.png


https://www.youtube.com/watch?v=llDH22x1zl0

[lohring]

The NACA reviewed a very large number of two stroke designs. I don't think they missed many possibilities in the pre tuned pipe era.

Lohring Miller

348856

[ceci]

The NACA reviewed a very large number of two stroke designs. I don't think they missed many possibilities in the pre tuned pipe era.

Lohring Miller

348856

CROSSFEED SCAVENGING FOR MULTI-CYLINDER TWO CYCLE ENGINES
Does this work (I don't mean the US3289656A patent, if not the concept), I don't know, so far only the testimony of wobbly makes me think so.
For this to work of course you need a tuned pipe

[andreas]

CROSSFEED SCAVENGING FOR MULTI-CYLINDER TWO CYCLE ENGINES
Does this work (I don't mean the US3289656A patent, if not the concept), I don't know, so far only the testimony of wobbly makes me think so.
For this to work of course you need a tuned pipe

I didn't read the patent through, but is it not about delaying the charge, with a cylinder that is 90* behind? I don't see the resemblance to Wobblys sea doo.

[ceci]

I didn't read the patent through, but is it not about delaying the charge, with a cylinder that is 90* behind? I don't see the resemblance to Wobblys sea doo.

The video is the same as wobbly, with the difference that express conduits are used for it (wobbly uses the exhaust pipe itself).
Advantages, because you can incorporate some type of mechanism as a valve that controls and closes when the engine needs it.
Where do you think the Wobbly sea doo engine crankcase would have the lowest pressure be it, before TDC, at TDC or after TDC?


https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=339809&d=1544250658

[andreas]

That video, you made it? I'm not sure what you mean. The sea doo engine has a y-pipe I think, the lowest pressure would vary in respect to crank angle, and why it made more power is not really cuncluded either, if I follow.

[ceci]

That video, you made it? I'm not sure what you mean. The sea doo engine has a y-pipe I think, the lowest pressure would vary in respect to crank angle, and why it made more power is not really cuncluded either, if I follow.

If you mean the video of the 3D figures, if I did it, if what you mean if I have done something like that with a real engine, NO, doing it is not within my reach.
The bottom line is: can cross feed work on engine twins?

[andreas]

At least I can't think of any reason why it would be benficial.

[ceci]

And adding to the effect of having very high exhaust duration you can cut the skirts short such that the port is open a few mm when the piston is at TDC.
Wreaks havoc with the jetting , but in the project i tried that we were using big pumper carbs.
Very easy to adjust the fuel curve as was needed - but I doubt a normal carb could be made to work.
This setup on a " stock " 950 SeaDoo gave an added 8 Hp in about 80 , so 10% - enough for the title at Havasu.
On a 1180 twin race motor the bump was 15 Hp in 120 so a little less.


That fact intrigues me, filling (supercharging) supplement volume charge for the exhaust why it happens.
How to get that little supplement volume of cargo to the exhaust:
The depression of the main exhaust creates a venturi effect and attracts it
the inertia of the incoming mixture forces it out through this small slot.
Which of the two causes can it be?


I believe it's the split suction wave from the single diffuser that find it's way into the tdc side crank case. Or it's explained on previous pages.


Can you give both at the same time?

[andreas]

As I said i'm not excactly sure why that engine made more power. And also as I said, I think it had a shared pipe with a y- section to the cylinders, so there is no need to have ducts from one cylinder to the other. If your idea works with separate pipes, I don't know.

[ceci]

As I said i'm not excactly sure why that engine made more power. And also as I said, I think it had a shared pipe with a y- section to the cylinders, so there is no need to have ducts from one cylinder to the other. If your idea works with separate pipes, I don't know.

sorry, I did not say anything that it is for separate pipes, also it can be controlled with a valve that activates or deactivates it.
With a little imagination we can dream of a Yamaha TZ250 type engine, powered by the 24/7 valve system, in addition to cross-feed "supercharging" through the exhaust, with a considerable increase in power.

https://i.ytimg.com/vi/f0ylb4wUKjY/hqdefault.jpg

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/BZlZSZI3L8Y" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>


This is the work I would like to have done myself in my own shed if I was clever enough.....


<iframe width="560" height="315" src="https://www.youtube.com/embed/IGuF1Uwupcs" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

[andreas]

https://www.youtube.com/watch?v=0bYkZYUxW-s

[OopsClunkThud]

started a new thread for geeking out on the CFD details:

https://www.kiwibiker.co.nz/forums/showthread.php/188954-Computational-Fluid-Dynamics-(CFD)-Q-amp-A

Thinking this will make it easier to track and find the boring data like gas properties and how to generate good mesh boundary layers, and then we can just post the results and exciting stuff here.

[TZ350]

More intriguing stuff from the Shed of Two Stroke Stuffing ......

<iframe width="560" height="315" src="https://www.youtube.com/embed/l6E2SkWv9jI" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/pJqRedNVAk4" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

[F5 Dave]

Thanks for posting that Rob. Held 6" from my face my heartrate was going. I love 50s, even on long tracks.

[TZ350]

I love 50s, even on long tracks.

Yes, I am enjoying mine. RG50 in NF4 chassis with a few mods to make it a bit more comfy to ride. I have ridden it at Hampton Downs club track and Tokoroa. Came last every time.... :laugh:

[sniemisto]

Hello everybody,

I've been reading these super interesting topics here and in pit-lane. Thanks everybody for this great knowledge that is shared in here! :yes:
I'd like to introduce myself before posting anything else. I'm 32 years old guy from Finland and been diving inside 2-stroke tuning "rabbit hole" since I started tuning Derbi engine for Finnish moped endurance class. I'v been working as motorcycle mechanic 15 years, but mainly with 4-stroke street bikes.

Our endurance team has Derbi Senda DRD Pro with modified Athena power valve cylinder, original pneumatic PV replaced with electronic Aprilia Rave controlled by Ignitech unit.
I'm now planning new engine version and got new fresh Athena cylinder to avoid mistakes I've done with first one..
Been practicing with EngMod2t and playing with different variations. We have just built inertial dyno and that is starting to be finally set up smooth enough to fine tune simulation model to correspond.

Question:
There has been a lot of discussion about piston pin plugs and how it's benefit varies depending on porting, plug style, ...
I have still missed following point. Is gaining blowdown specific time area by extending auxliary exhaust ports over piston pin until cylinder center line making more gains than what is given away with unplugged pin hole? Yes, depends on many thing, but can we have some rule of thump in case of modern high performance engine?

With best regards,
-Sami-

[jamathi]

Hello everybody,

I've been reading these super interesting topics here and in pit-lane. Thanks everybody for this great knowledge that is shared in here! :yes:
I'd like to introduce myself before posting anything else. I'm 32 years old guy from Finland and been diving inside 2-stroke tuning "rabbit hole" since I started tuning Derbi engine for Finnish moped endurance class. I'v been working as motorcycle mechanic 15 years, but mainly with 4-stroke street bikes.

Our endurance team has Derbi Senda DRD Pro with modified Athena power valve cylinder, original pneumatic PV replaced with electronic Aprilia Rave controlled by Ignitech unit.
I'm now planning new engine version and got new fresh Athena cylinder to avoid mistakes I've done with first one..
Been practicing with EngMod2t and playing with different variations. We have just built inertial dyno and that is starting to be finally set up smooth enough to fine tune simulation model to correspond.

Question:
There has been a lot of discussion about piston pin plugs and how it's benefit varies depending on porting, plug style, ...
I have still missed following point. Is gaining blowdown specific time area by extending auxliary exhaust ports over piston pin until cylinder center line making more gains than what is given away with unplugged pin hole? Yes, depends on many thing, but can we have some rule of thump in case of modern high performance engine?

With best regards,
-Sami-

My answer is a definite YES!
At Aprilia we mostly tested with unplugged piston pins, as the plugged pins were too expensive.
Widening the auxiliar ports was done numberous times, and always gave more power!!!

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/644fAihwgU4" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

[sniemisto]

My answer is a definite YES!
At Aprilia we mostly tested with unplugged piston pins, as the plugged pins were too expensive.
Widening the auxiliar ports was done numberous times, and always gave more power!!!

Thanks Jan for the info!
Now I can start widening auxiliar ports and think about buying torlon bar later [emoji41]

Many sources was telling to avoid relieving to pin bores but that must be now considered as old fashion. That was also reason why I abandoned Athena pistons with relief around pin bore.


Sent from my iPhone using Tapatalk

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/eRItqiCFuQE" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Ok. So its drag racing, but a two stroke drag racer. Great two stroke sound at WOT. And also if you pay attention to the technical talk and trip around the work shop you will pickup that its fuel injected. So the fastest 2T drag bike in the world is fuel injected.

[wobbly]

Widening the Aux ports to bore center does two things , increases Blowdown STA and increases port linking to the A Transfer.
You can reduce the effect of linking by making the Aux duct very shallow in depth at its rear wall next to bore center , and also grinding the port shape with alot of taper upwards from front to back.
This gives alot of area just as the port opens , with the max pressure differential , but reduces the linking time.
With capped pins the duct can have much less of a tangential exit angle on the rear , top , corner wall , with a nice sweeping pocket that improves flow and power.

Be carefull with using Frits idea of using Torlon inserts , that effectively blanks off the pin bore in the piston.
In the TM kart engines this reduced the access of lubrication from transfer flow into the piston bearing surface , and the pin ends turned blue.
Jan said that the Aprilia did the same , but I never wanted to find out if the pin bore became unreliable.
Making tophat CNC steel plugs and having them laser welded into stock pins is cheap , and relaible and just as effective power wise.
Maybe drilling a hole upward in the bottom of the piston pin boss would fix the issue , again I wasnt keen on destroying a motor if this was unreliable.

[jamathi]

Widening the Aux ports to bore center does two things , increases Blowdown STA and increases port linking to the A Transfer.
You can reduce the effect of linking by making the Aux duct very shallow in depth at its rear wall next to bore center , and also grinding the port shape with alot of taper upwards from front to back.
This gives alot of area just as the port opens , with the max pressure differential , but reduces the linking time.
With capped pins the duct can have much less of a tangential exit angle on the rear , top , corner wall , with a nice sweeping pocket that improves flow and power.

Be carefull with using Frits idea of using Torlon inserts , that effectively blanks off the pin bore in the piston.
In the TM kart engines this reduced the access of lubrication from transfer flow into the piston bearing surface , and the pin ends turned blue.
Jan said that the Aprilia did the same , but I never wanted to find out if the pin bore became unreliable.
Making tophat CNC steel plugs and having them laser welded into stock pins is cheap , and relaible and just as effective power wise.
Maybe drilling a hole upward in the bottom of the piston pin boss would fix the issue , again I wasnt keen on destroying a motor if this was unreliable.

The pin ENDS turned blue, but the pin itself not...
There NEVER was a lubrication problem!!!

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/P2hgK-wZ1XA" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Thailand, Drag Racing Motorcycles. 150cc 9 sec pass's on Nitrous and the Motorcycle enthusiasts who come to watch.

[F5 Dave]

Where do they get those helmets?!.

[Frits Overmars]

Where do they get those helmets?!.It looks like a car helmet to me. These have a lower visor opening than motorcycle helmets because the driver leans back.

[F5 Dave]

You learn something new every day.

[pete376403]

I have a Bell Star 120 like that from about 40 years ago. Was made in response to the complaint that a regular Bell Star was limited peripheral vision, so this one has 120 degrees peripheral

[wobbly]

Here is a pic of the small end pin after around 10 dyno sessions in the TM engine with full cover Torlon caps.
I was way too scared of destroying a customers engine to go any further with that setup.
Now I can get enough caps CNC'd and have them laser welded into 5 pins for under $200NZD , cheap for the performance gain , and reliable.

[flyonly]

Here is a pic of the small end pin after around 10 dyno sessions in the TM engine with full cover Torlon caps.
I was way too scared of destroying a customers engine to go any further with that setup.
Now I can get enough caps CNC'd and have them laser welded into 5 pins for under $200NZD , cheap for the performance gain , and reliable.

Who can do the laser welding in NZ?


Sent from my iPhone using Tapatalk

[dtenney]

Here is a pic of the small end pin after around 10 dyno sessions in the TM engine with full cover Torlon caps.
I was way too scared of destroying a customers engine to go any further with that setup.
Now I can get enough caps CNC'd and have them laser welded into 5 pins for under $200NZD , cheap for the performance gain , and reliable.

We have made torlon caps in the same shape as your welded end cap. We see similar signs of heat at the ends of the wrist pin but have not had any failures. Why does the welded cap not show the same signs of heat as a similarly shaped Torlon cap?

[jonny quest]

Foul stroke Ex valves have sodium? Filled hollow stems in some applications for heat dissipation.

May be a good wristpin solution?

[wobbly]

DT , the torlon caps I made ( Kentastic actually ) were held in by the clip and covered the pin hole completely.
But yours colour up , and dont fail ?
The tophat welded pins allow lube into the piston pin bearing surface - and show no heat issues at all , plus identical power.
No other difference , so I can only assume for some reason the TM Vertex piston does not have sufficient rear lube entry ( sounds rude , sorry ).
As I said I aborted the Torlon tests as destroying a customer engine isnt really an option - giant blouse I know.

[wobbly]

Fly - Laser Welding NZ Ltd in Auckland , not hard to remember.

[Condyn]

I have a few photos saved of what appears to be a pin failure possibly propagated by the plugs. Also an interesting method to secure them. Looks almost like a pin holding them in.

[SwePatrick]

I was thinking about torlon, but had an 'way out there' thought.
In modern brakecalipers in often american cars, the pistons are made from some sort of plastic material
Wouldn´t it be able to take the heat as wristpin plugs?

[Frits Overmars]

I was thinking about torlon, but had an 'way out there' thought. In modern brakecalipers in often american cars, the pistons are made from some sort of plastic material. Wouldn´t it be able to take the heat as wristpin plugs?I suppose brake caliper pistons will get hotter than piston pins, so they should be able to take the heat, but taking the heat is no problem for Torlon either;
the problem seems to be with the pins themselves, and using a different synthetic plug material won't change that.

[TZ350]

More progress from Alex at Two Stroke Stuffing.

<iframe width="560" height="315" src="https://www.youtube.com/embed/e4WKOA2jqPg" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

[TZ350]

Reading spark plugs. 2Stroke Stuffing. Alex.

<iframe width="560" height="315" src="https://www.youtube.com/embed/uHbhoX0s5_8" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

[TZ350]

Reading Spark Plugs. Steve Tech.

<iframe width="560" height="315" src="https://www.youtube.com/embed/MecCoercp-s" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

[TZ350]

Reading Spark Plugs to understand general engine condition. Goss Garage.

<iframe width="560" height="315" src="https://www.youtube.com/embed/lVCs5gWLUyI" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

[dtenney]

DT , the torlon caps I made ( Kentastic actually ) were held in by the clip and covered the pin hole completely.
But yours colour up , and dont fail ?
The tophat welded pins allow lube into the piston pin bearing surface - and show no heat issues at all , plus identical power.
No other difference , so I can only assume for some reason the TM Vertex piston does not have sufficient rear lube entry ( sounds rude , sorry ).
As I said I aborted the Torlon tests as destroying a customer engine isnt really an option - giant blouse I know.

We do see the heat issue referred to by Jan at the outer ends of the wrist pin. Having said that, we have not had any failures. We are running methanol in our motors so I do not know if runnning on gasoline would be ok.

[SwePatrick]

I suppose brake caliper pistons will get hotter than piston pins, so they should be able to take the heat, but taking the heat is no problem for Torlon either;
the problem seems to be with the pins themselves, and using a different synthetic plug material won't change that.

I was thinking it as an cheap easy to come by replacement for those who want´s to test the idea =)

[SwePatrick]

More progress from Alex at Two Stroke Stuffing.

<iframe width="560" height="315" src="https://www.youtube.com/embed/e4WKOA2jqPg" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Finally Alex has come to his senses :)
In my eyes the 100% port with no beam to support the ring is a enginedisaster you install.
Not waiting to happen, you install the problem and it is bound to happen very very soon.

And a hot tips for you Alex, do not turn around the engine directly with that drill after it stopped.
Just turn around by hand first and feel it.
Saves you money in the end, i promise!

[wobbly]

The 100% Exhaust port with the Savice patented reversed Dykes type L ring worked perfectly during hours of testing of pistons and rings made by Vertex.
I dont understand why Alex went off on a tangent with the pinned ring idea , all that was needed was attention to the clearance detail of trapping the ring , preventing any bulge out into the port.
This idea certainly isnt an automatic disaster , its been done , and proven.
Of course a point load on a highly stressed thin section retaining hole is going to cause instant issues.
The original reversed L ring had the bulging load spread out over near 1/2 the vertical legs circumference , and thus was no problem mechanically at all.
And the bore edges of the port need to be chamfered properly , before plating , and dressed afterward with cratex/cotton mops in a die grinder , exactly as is required with a normal 72% port - not just rubbed
by hand with a strip of sand paper.
As always , the devils in the detail.

[SwePatrick]

That L-ring test, Was it a highrevving small engine?
As i always will state that the piston rocks due to it´s tapered form.
And i will still belive that´s why the ring always catches the lower part of the port, as the piston is always prone to rock in tdc and bdc.

Due to rocking, the ring needs to have a bit of travel in and out of it´s groove and never be restricted before the piston rocking is halted by cylinderwall, otherwise it will not seal in upper part of cylinder as it should, and with that loose a lot of power.

A 'lowrevving' non highperformance engine can have less taper to the piston and it makes the piston rock less(less friction,less heat), and thereby have more control of the ring.

[TZ350]

That L-ring test, Was it a highrevving small engine?
As i always will state that the piston rocks due to it´s tapered form.

It is true that a piston is tapered, but the taper is calculated so that the piston become more parallel when it is at working temperature. Because the crown and the upper part of the piston has more mass and runs hotter. For both reasons it therefore expands more. Also the same reason pistons are oval and narrower on the sides to accommodate the expansion of the extra mass around the gudgen pin bosses.

Plenty of performance high revving Kart engines had L-ring or Dykes ring configuration.

[Frits Overmars]

More progress from Alex at Two Stroke Stuffing.
<iframe src="https://www.youtube.com/embed/e4WKOA2jqPg" title="YouTube video player" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" width="560" height="315" frameborder="0"></iframe>
I love watching "Two Stroke Stuffing" on YouTube and seeing how Alex Degnes is enjoying his hobby and at the same time is doing a wonderful job at promoting the two-stroke engine. Of course I also enjoy the way he makes good use of information, like the transfer layout in his present cylinder which mirrors my scavenging concept, his plan to incorporate my 24/7 inlet timing, and now his new cylinder with symmetrical scavenging.The latter will give him a lot more blowdown angle.area than his unbridged exhaust port experiment, and a lot more transfer angle.area to go with the enhanced blowdown.
I can't wait to see his next videos. I don't mind admitting that from time to time it's not only a trip down memory lane for me, but also a shameless ego trip :p.
348909348908348906 348907 348910

[Frits Overmars]

Reading Spark Plugs. There is just one thing missing in those spark plug reading videos: reading the price tag on a spark plug. I have never in my life chopped a spark plug just to get a better look at its insulator, and to the best of my knowledge neither has Jan Thiel. A 20x-magnifying glass and some light is all you need.

[OopsClunkThud]

The bottom edge of the exhaust could get a huge radius as it has zero impact on the timing. On the sides and roof of the exhaust adding a radius comes at the expense of port area as it has to be done within the confines of the port width and timing. But the port floor is the only part of the exhaust where adding a radius can be outside of the port area at least down to ~BDC.

[jonny quest]

To make the FOS cylinder work, I really think a dished piston, and a downward transfer roof is the answer.

Too much short circuit issues with transfers directly under exhaust port.

[wobbly]

The reverse L ring tests were done on a Rotax 128 , that reved to 14500 , no failures were seen once the radial clearance holding the vertical leg trapped within the piston groove
was correct.
Too tight and it caused premature blowby , too loose and you could see scuffing beginning on the port corner radi.

[jamathi]

There is just one thing missing in those spark plug reading videos: reading the price tag on a spark plug. I have never in my life chopped a spark plug just to get a better look at its insulator, and to the best of my knowledge neither has Jan Thiel. A 20x-magnifying glass and some light is all you need.

No, I never did!
I always looked at the piston top.....
Even if I had to take off the cylinder head sometimes!!!!
The piston also tells a lot about transfer flow and detonation....
I also looked a lot at the inside of the piston.

[ken seeber]

“What’s is this Ken, another one?”
“Yep”
“Care to explain”
“OK”
Something that has been in the mind for ages. Did make a post about it, see 29 May, 2015. See a couple of pics around a KZ port model
This time, it will be trialled on an ARC watercooled cylinder. (The ARC kart engine was Australian made kart engine that was closely based on the Yamaha KT100S engine, Ø52 *46.1. Many parts were interchangeable. Versions were made with both air and watercooled cylinders and heads, both being piston ported inlet).

Had one kicking around, so why not. Welded on some sideplates at a reasonably appropriate angle and in conjunction with my newest best friend, Devcon F, filled and created two passages aligned and connected to the A ports, no connection to the crankcase at all. This means all flow through the original carb’d inlet, through the crankcase and into the cylinder will be via the small B ports.

The whole operations will depend on all that huffing, blowing and sucking that Wob, Neels and Frits go on about :yes:. . The key one here will be the sucking.

Just so many questions:
• Will the small B ports be enough to get to the tuned speed?
• Will it be incredibly noisy?
• Are you going to add more lube to the crankcase inlet when the direct inlets are working?
• Will it possibly create some spectacular fires?
• How to control a mixture into the intakes?
• Will the transition to opening the inlets will be interesting or very interesting?
• How to even test it?
• Do you need a special exh system rather than the regular kart header and muffler?
• Etc.
Unfortunately not enough answers.

Watch this space.

348911348913348914348915

[ken seeber]

More happy snaps:

348916348917348918348919

[pete376403]

No, I never did!
I always looked at the piston top.....
Even if I had to take off the cylinder head sometimes!!!!
The piston also tells a lot about transfer flow and detonation....
I also looked a lot at the inside of the piston.

Gordon Jennings wrote that he jetted according to the charred carbon (or lack of) on the underside of the piston crown. Wrote that was a very good indicator of the heat going into the piston crown, and how close it was to tipping over the ragged edge.

[wobbly]

We dont see any charred carbon on piston undersides nowdays , as the oils are much , much better and cleaner. The rare time would be with too much advance , colouring up the middle only.
A couple of really good oils have lost favour in karting due to being so clean , they hardly colour up the piston top after a couple of practice sessions. Vroom is one.

In KZ and classic bike racing I know exactly the egt/RAD that makes best power , just short of detonation on the piston inlet side timing edge , trapped by the squish band.
So by using the the local airport weather station info on my phone , I dont even need to take the plug out - except to check occasionaly that my calculation is correct .
I just look at the graph made from 3 data points of RAD ( Density Altitude ) and jetting size that achieved the desired egt previously - and fit the correct jet - absolutely repeatable and reliable.
All this is doing technically is replicating the best power bsfc. More air , needs more fuel , makes more power , but will achieve axactly the same egt on the day.

One additional tuning aid not mentioned is that using plugs with Platinum fine wire ground electrodes , the colour heat change point on the leg gives a very accurate metric of the tune.
The very distinct line , when its around 3/4 back from the tip , indicates the combination of jet and timing is on the money.
This point will change much , much quicker than poking your nose down inside the plug insulator , looking for the depth of soot ring with a x20 glass - as this takes quite a few Km of hard running to be
distinct enough , again , more especially with the soot free oils we have now.

When tuning a new setup , I like to use a castor based oil such as Maxima 927 or even the real old but real good Castrol 976 , as the castor esters colour up the piston and plug very quickly.

[sniemisto]

I have not seen any sign of brown ring on insulator after WOT run with fresh spark plug, even with having main jet slightly on rich side. I have tought this is because of 5% ethanol in fuel, but reason might also be good modern synthetic oil (Castrol Power 1).

I was just going to test effect of widening auxiliarys, but I was facing blown head gasket issue I need to deal up first.
Gasket blow up second time after just 3 hrs of racing. Head is not wrapped so I assume it is too flexy, as its only 8,2mm thick compared to 12,2 thick Malossi head.

348925

Time to fabricate new head insert and also start using KTM SX50 viton o-ring gasket instead of original steel. Steel gasket is coolant flow restrictor from head to cylinder and I'm making new head like Malossi, with skirt going over water channels. I have 130mm bar of 6082-T6 aluminium so I will have enough material to leave skirt to manually grind to fit over transfers.

348926

Need to think bit about coolant holes, maybe having slightly bigger holes on back for cooler water around transfer, but that can be restricting amount of water going over head insert.

This is also good time to machine fins on water side of combustion chamber. Thinking about DEA style steps or horizontal fins. I'm doing it in manual lathe, it would be possible to have vertical fin over squish band area if I make some thin tool for it.

348927

[wobbly]

Why do you want steps or fins on the back side of the combustion chamber.
This is one of those old Monkey see Monkey do scenarios.
Cooling the chamber , does nothing but pull heat out of the combustion process.
The more heat in the chamber , the greater the gas expansion , the greater the power.
Throwing away heat into the water , is throwing away horsepower.
The better thing to spend time or money on is to arrange water to get close to the plug threads , and ceramic coat just the chamber , not the squish band , to retard heat loss into the water.

[ken seeber]

Just looked, and relooked, at Alex’s latest 2 stroke stuffing vid and he showed a “sketch” of a possible future engine design. At around the 11 min stage in the vid.

It shows 6 of axisymmetric scavenge/transfer passages. Nothing new there. No conventional exh outlets though? Yet to be drawn in?

No. he is going to rotary valve the exhaust. Early exh valve closure combined with a supercharged crankcase will potentially allow the cylinder pressure to rise above the usual pressure in the cylinder at the time of EPC = increased trapped mass = more power.

Watch his space.

[Vannik]

Early exh valve closure combined with a supercharged crankcase will potentially allow the cylinder pressure to rise above the usual pressure in the cylinder at the time of EPC = increased trapped mass = more power.

My experience with supercharging a 2T is to NOT charge the crankcase but use external scavenging chamber. You end up doing a double amount of pumping work, first by driving the supercharger and then again by compressing it further in the crankcase, it does not make sense.

You will also need the early closing exhaust port otherwise it just pumps everything into the exhaust. And a tuned pipe does not work unless you only charge a few kPa.

[ceci]

My experience with supercharging a 2T is to NOT charge the crankcase but use external scavenging chamber. You end up doing a double amount of pumping work, first by driving the supercharger and then again by compressing it further in the crankcase, it does not make sense.

You will also need the early closing exhaust port otherwise it just pumps everything into the exhaust. And a tuned pipe does not work unless you only charge a few kPa.

That depends on the type of supercharging used.
If you use the auxiliary pump piston, depending on the configuration, you can have both circumstances or just one, example: motobecane 99Z in this one there are both, montesa alcor xlv only the first.

[katinas]

"Sulzer" used rotating exhaust valve in pair with intake reed valve on the two stroke turbo charged old marine engine.

[SwePatrick]

It is true that a piston is tapered, but the taper is calculated so that the piston become more parallel when it is at working temperature. Because the crown and the upper part of the piston has more mass and runs hotter. For both reasons it therefore expands more. Also the same reason pistons are oval and narrower on the sides to accommodate the expansion of the extra mass around the gudgen pin bosses.

Plenty of performance high revving Kart engines had L-ring or Dykes ring configuration.

Yes, and when piston crown is growing the tolerances changes in the ringgroove also, pushing the ring even harder into a port.
not on ordinary pistons as they have room, but that locating ping maybe didn´t.

[Vannik]

That depends on the type of supercharging used.

He plans to use this:

348929

[yatasaki]

"Sulzer" used rotating exhaust valve in pair with intake reed valve on the two stroke turbo charged old marine engine.

And they were disaster to maintain and work with

[ceci]

He plans to use this:

348929

My thoughts are: best supercharger out there for the 2S, it's a tuned pipe.
This Konstantin Starodetko engine doubles the power compared to the same one without supercharging, but it does not get more KW than a yamaha tzr 250

https://media-exp1.licdn.com/dms/image/C4E12AQEXJKCtGwUIQw/article-inline_image-shrink_1500_2232/0/1520177425330?e=1625097600&v=beta&t=OcMbWoXZtA1rUb_E_0yWyyUyFP6X-0c6uCN7WlrCzzw

https://media-exp1.licdn.com/dms/image/C4E12AQHf_ul0VswqLg/article-inline_image-shrink_1500_2232/0/1520147243816?e=1625097600&v=beta&t=kXMZjlbccKNhm83CU6Tn8y3JBF5Ffh6Tv04b-W_xSqM

https://i.ebayimg.com/images/g/A48AAOSwT6pVyzPB/s-l400.jpg

[lohring]

As I've posted before, supercharging a two stroke requires raising the exhaust pressure along with the intake pressure. Unlike in a four stroke, this doesn't produce negative work on the piston since it all happens at BDC, not during a full upstroke of the piston. Tuned pipes supercharge the cylinder in this way as do turbochargers. Mechanical superchargers alone without some exhaust restriction will blow everything out the exhaust without raising the cylinder pressure. The blowers in most two strokes are just a more efficient substitute for crankcase pumping. Snowmobile engines are the most noted for taking advantage of all this, see below. I think there are small enough turbochargers today for this system to work on engines as small as 50cc.

Lohring Miller

348933 348934

[TZ350]

More brilliance from 2Stroke Stuffing.

<iframe width="560" height="315" src="https://www.youtube.com/embed/Q_48YIOSedc" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

[wobbly]

The problem is the Devil is in the detail.
Alex has given up on the 100% exhaust concept because he never got the detail correct regarding the trapping of the reverse L ring.
The concept has been proven , and patented , so it can be done .
Now we have a new concept - just because the old one was " too hard ".
Currently we have carbon fibre rorary valve discs , with a ton of lubrication being applied with cold intake fuel/air and even with lots of development , this system
has wear issues.
What is going to happen to a stainless ( I assume ) rotary valve subject to 650* C and virtually no lubrication at all - yea sure , plastering ceramics all over the place may help.
Hate to be negative , but read again the first line.

[SwePatrick]

Why invent the wheel twice?

There are already twostroke supercharged engines out there with more efficient scavenging.

Twostroke diesels!

The same design is ofcourse usable with petrol, just lower the compression and change the glowplug with a sparkplug.

348935

Problem is that a small 50cc twostroke probably doesn´t have power enough to turn it on idle.
This complicates it all, magnetic clutch might be an answer.
And, no you don´t need any reedvalve.
Lastly, it also need an oilpump to lubricate the bearings in crankhouse and lubricate the bearings in the supercharger.

[ceci]

The only thing I agree with is his suspenders.
Simplicity in mechanism, complexity in materials.
Renault has been researching this type of engine for many years, supercharged and with valve-controlled non-asymmetric exhaust.

https://3.bp.blogspot.com/-YE8_5EBIosw/VIw8A32fn_I/AAAAAAAAS3A/q7YI4VFpCnU/s1600/renault-730cc-two-stroke-two-cylinder-super-charged-turbo-charged-diesel-engine01.jpg

[husaberg]

Why invent the wheel twice?

There are already twostroke supercharged engines out there with more efficient scavenging.

Twostroke diesels!

The same design is ofcourse usable with petrol, just lower the compression and change the glowplug with a sparkplug.

348935

Problem is that a small 50cc twostroke probably doesn´t have power enough to turn it on idle.
This complicates it all, magnetic clutch might be an answer.
And, no you don´t need any reedvalve.
Lastly, it also need an oilpump to lubricate the bearings in crankhouse and lubricate the bearings in the supercharger.

I could be wrong but i am not so sure the detroits are operated above the pressures of what a conventional 2 stroke is unless it's supercharged and turbocharged.
The roots blower just makes up for the lack of crankcase.

[ceci]

As I've posted before, supercharging a two stroke requires raising the exhaust pressure along with the intake pressure. Unlike in a four stroke, this doesn't produce negative work on the piston since it all happens at BDC, not during a full upstroke of the piston. Tuned pipes supercharge the cylinder in this way as do turbochargers. Mechanical superchargers alone without some exhaust restriction will blow everything out the exhaust without raising the cylinder pressure. The blowers in most two strokes are just a more efficient substitute for crankcase pumping. Snowmobile engines are the most noted for taking advantage of all this, see below.
Lohring Miller

348933

I return to expound, the concept that to increase the power of a 2S parallel twin, a turbocharger is not necessary.
I accompany it with enlightening images.
From my point of view, the brake for the crankcase feeding is the pressure in the crankcase and the later it starts, it is the more favorable for the use of a 24/7 valve.

[SwePatrick]

I could be wrong but i am not so sure the detroits are operated above the pressures of what a conventional 2 stroke is unless it's supercharged and turbocharged.
The roots blower just makes up for the lack of crankcase.

That´s why you add a turbo on top of everything.

Alex setup is no different that an old diesel as for trapping air.

[Peter1962]

More brilliance from 2Stroke Stuffing.

<iframe width="560" height="315" src="https://www.youtube.com/embed/Q_48YIOSedc" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Will a rotary valve by this design be able to cope with the extreme pressure and heat that is coming from an exhaust chamber ? Maybe a solution like RCV designed, would be more suitable ? (not for intake, but possibly for exhaust it could work ?
https://www.rcvengines.com/technology/

[Norman]

Regarding turbocharging of two stroke engines.

Lennarth Zanders work.

Power up to ~70 hp was seen on dyno (125cc) as I understand reading the paper.

https://www.sae.org/publications/technical-papers/content/2021-01-0642/preview/

[lodgernz]

Will a rotary valve by this design be able to cope with the extreme pressure and heat that is coming from an exhaust chamber ? Maybe a solution like RCV designed, would be more suitable ? (not for intake, but possibly for exhaust it could work ?
https://www.rcvengines.com/technology/

Alex drew a disc valve, but he mentioned it could be a drum valve, which would handle the pressure much better.

[F5 Dave]

Didn't Lotus piss around with barrel valve 2 stroke in, erm. . . 2000ish?

[ken seeber]

Didn't Lotus piss around with barrel valve 2 stroke in, erm. . . 2000ish?

Dave they certainly did, in the late 90s. Called the Lotus Omnivore. Orbital made some of the pistons for their first prototypes.

Such a simple mechanism: https://www.youtube.com/watch?v=fIG9pWldO8U

[TZ350]

Didn't Lotus piss around with barrel valve 2 stroke in, erm. . . 2000ish?

Lotus sleeve or rotary valve two stroke development. https://www.jstor.org/stable/44611314?seq=1

[lodgernz]

Back in the 1950s, when I was about 12, I tried to make a 4-stroke engine. This is the head:
348949

Would never have worked.

[lohring]

Really high power two strokes were investigated starting in the 1930s by Sir Harry Ricardo. His testing resulted in the Rolls Royce Crecy (https://en.wikipedia.org/wiki/Rolls-Royce_Crecy). However, gas turbines were going to be the obvious choice for all but the smallest aircraft engines, so development stopped. In the end he got a BMEP of 325 psi with an intake pressure of 36 psi and an exhaust back pressure of 12 psi. That was more than enough exhaust pressure to power a compressor. Napier took the concept even farther with the Napier Nomad (https://en.wikipedia.org/wiki/Napier_Nomad). There a significant amount of turbine power could be fed back into the crankshaft.

Lohring Miller

348952

[F5 Dave]

I'm confused. What are suspenders for?

Also why not just make a 250? Light weight, small size and fuel frugality seem to have been jettisoned, so. . . ..?

[Flettner]

Forget all this nonsense, just go Uniflow. 175cc

[yatasaki]

Forget all this nonsense, just go Uniflow. 175cc

Transfers tangentialy directed or other options?

[Flettner]

Transfers tangentialy directed or other options?

This one in the video, two tangental, four central collision, each cylinder. Transfer pistons 56 dia, exhaust pistons at 50 dia. So a little squish.
https://youtu.be/BPr694nlUKE

[Flettner]

Transfers tangentialy directed or other options?

This one in the picture, other.

[wobbly]

But Flettner , the desire was to make the most powerfull 2T /cc on the planet , not a tractor engine.

[TZ350]

But Flettner , the desire was to make the most powerfull 2T /cc on the planet.

That would be best done with a super or turbo charged Creasy style two stroke sleeve valve engine.

348983 Sleeve valve arrangement Flettner made a while back.

[Flettner]

Cant argue with 325 BMEP.
https://youtu.be/6keqpL3rmwk

[wobbly]

So using the usual formulae , starting with BMEP = 150.8 x Torque ( ft lbs ) / Cubic inches and transposing Hp = T x rpm/5252 into this for a 50cc engine pulling 17,000 rpm
we end up with ( 50cc = 3.05 cu in )
bmep ( 325 ) x 3.05 x 17,000 /150.8 x 5252 = 21.28 Hp.
This would give us something worthwhile - making the assumption of course that the sleeve and its associated mechanism can survive at 17,000 rpm.
This is a modest 22M/sec piston speed for a square 50cc engine.
Achievable , dunno , you tell me.

[Flettner]

No, Harry Ricardos supercharged sleeve valve twostroke engine running in his back yard for 1000 hours. 325 BMEP, Id be happy with that. Open ended sleeve, no sealing ring.
Not my one, dont know what BMEP it is. Probably 5.

[andreas]

So using the usual formulae , starting with BMEP = 150.8 x Torque ( ft lbs ) / Cubic inches and transposing Hp = T x rpm/5252 into this for a 50cc engine pulling 17,000 rpm
we end up with ( 50cc = 3.05 cu in )
bmep ( 325 ) x 3.05 x 17,000 /150.8 x 5252 = 21.28 Hp.
This would give us something worthwhile - making the assumption of course that the sleeve and its associated mechanism can survive at 17,000 rpm.
This is a modest 22M/sec piston speed for a square 50cc engine.
Achievable , dunno , you tell me.

Is this still the two stroke forum? 75.4 ~42.6 hp

[Frits Overmars]

So using the usual formulae , starting with BMEP = 150.8 x Torque ( ft lbs ) / Cubic inches and transposing Hp = T x rpm/5252 into this for a 50cc engine pulling 17,000 rpm
we end up with ( 50cc = 3.05 cu in )
bmep ( 325 ) x 3.05 x 17,000 /150.8 x 5252 = 21.28 Hp.
This would give us something worthwhile - making the assumption of course that the sleeve and its associated mechanism can survive at 17,000 rpm.
This is a modest 22M/sec piston speed for a square 50cc engine.
Achievable , dunno , you tell me.Wob, good news: lately we have a wonderful system of units available: the kilogram-meter-second system. It functions in the same way as your trusted hundredweight-furlong-fortnight system, but without your precious constants. It may also save a few cubic feet of aspirin.
By the way, if your desire is to make the most powerful 2T /cc on the planet, the bad news is that 21,28 hp out of a 50cc engine won't cut it. In the Netherlands alone, there are already various 50cc machines with 24 hp on board, not at 17,000 rpm but well below 16,000 rpm. And looking a bit further, there was an Aprilia engine you may have heard of, called the RSA, with 54 hp at 13.000 rpm from 125 cc. A 50 cc engine with the same BMEP ought to deliver 29,6 hp at 17.800 rpm, so our 24 hp bikes are not really that special; they still have some way to go.

Either way, 'most hp per cc' is a pointless endeavor. I have a 6,5 cc engine lying here that produces 5 hp without supercharging, without nitro, without nitrous oxide, simply with 80% methanol and 20% oil (which is far too greasy for good power), and with glow plug ignition. With spark ignition it would probably reach 1000 horsepower per liter.
Hp per cc per 1000 rpm would be a better yardstick (or should that be meterstick nowadays)? :msn-wink:

[ken seeber]

Frits, just saw your post....your proposed specific power index looks more meaningful and relevant.

Still, I'll post what I was going to post

Below, as a refresher, is link to explain BMEP:

http://www.epi-eng.com/piston_engine_technology/bmep_performance_yardstick.htm

Not sure if this below covers the full history:

https://en.wikipedia.org/wiki/Rolls-Royce_Crecy

However, if it was going to seize, I’d take it in a tractor rather than 25,000 feet in the air…just a simple pain avoidance preference though…

[Frits Overmars]

Frits, just saw your post....your proposed specific power index looks more meaningful and relevant.
Still, I'll post what I was going to post
Below, as a refresher, is link to explain BMEP:
http://www.epi-eng.com/piston_engine_technology/bmep_performance_yardstick.htm
Not sure if this below covers the full history:
https://en.wikipedia.org/wiki/Rolls-Royce_Crecy
However, if it was going to seize, I’d take it in a tractor rather than 25,000 feet in the air…just a simple pain avoidance preference though…Ken, my proposal is no better than the BMEP-approach. I only left out the constants, so everybody should be able to do the math.
Speaking of which, I translated the Crecy's 5.1" bore x 6.5" stroke into 129,54 x 165,1 mm, giving 2175,93 cc per cylinder and 26.111 cc altogether.
I could not discover at what rpm the Crecy produced its maximum of 2729 hp, so I assumed it to be at the 2500 rpm that was quoted for its fuel consumption.
This would give 0,0418 hp per cc per 1000 rpm, 26% better than the 0,0332 hp/cc/1000rpm of the (unblown) RSA.
Makes me wonder what the RSA would do at the 100 kPa supercharger boost of the Crecy....
https://ww2aircraft.net/forum/threads/rolls-royce-crecy.50534/
348990

[husaberg]

Ken, my proposal is no better than the BMEP-approach. I only left out the constants, so everybody should be able to do the math.
Speaking of which, I translated the Crecy's 5.1" bore x 6.5" stroke into 129,54 x 165,1 mm, giving 2175,93 cc per cylinder and 26.111 cc altogether.
I could not discover at what rpm the Crecy produced its maximum of 2729 hp, so I assumed it to be at the 2500 rpm that was quoted for its fuel consumption.
This would give 0,0418 hp per cc per 1000 rpm, 26% better than the 0,0332 hp/cc/1000rpm of the (unblown) RSA.
Makes me wonder what the RSA would do at the 100 kPa supercharger boost of the Crecy....
https://ww2aircraft.net/forum/threads/rolls-royce-crecy.50534/
348990

The last version based on a single slave engine produced an estimated 5000HP from its 26 liters.


Only six complete examples were built when the research was terminated in December 1945. An additional eight vee twins were built. Serial numbers were even, Rolls-Royce practice being to have even numbers for clock-wise rotating engines when viewed from the front. Crecy number 10 achieved 2500 hp on 21 December 1944. Subsequently single cylinder tests achieved the equivalent of 5000 bhp for the complete engine.



no idea re the revs

but

The thrust produced by the two-stroke exhaust was estimated as being equivalent to an additional 30% increase in power at the propeller on top of the rated power of the engine, and was exceptionally loud.

[Flettner]

However, if it was going to seize, I’d take it in a tractor rather than 25,000 feet in the air…just a simple pain avoidance preference though…[/QUOTE]

😁 I soon learnt to test the uniflow jet boat upstreem in the river.

[wobbly]

So , apart from ignoring all the hideous cubic inches and ft/lbs etc , it would appear that even running the 50cc at 17000 , using sleeve valve and other of the planet
ancient technologies has no advantages , power density wise , over SOTA done properly.
If only NoLuc was 1/2 way right , sigh.

[andreas]

325psi/22.4 bar x 17000 rpm x 50cc = 42 hp

[Flettner]

325 BMEP , supercharged.
Actually last versions of Crecy were compound turbo / supercharged. Exhaust turbine added to crank power.
Im guessing that was more than 325 BMEP. However that is calulated?

[sniemisto]

Why do you want steps or fins on the back side of the combustion chamber.
This is one of those old Monkey see Monkey do scenarios.
Cooling the chamber , does nothing but pull heat out of the combustion process.
The more heat in the chamber , the greater the gas expansion , the greater the power.
Throwing away heat into the water , is throwing away horsepower.
The better thing to spend time or money on is to arrange water to get close to the plug threads , and ceramic coat just the chamber , not the squish band , to retard heat loss into the water.

Thanks Wobbly!
New head is now almost ready. I followed advice and focused getting water closer to the plug. Original plug hole o-ring was changed from axial to radial style and is now smaller diameter.

https://uploads.tapatalk-cdn.com/20210505/377f94a435633b1b40b66b646ca8656e.jpg

[Flettner]

Id still tend to run a uniflow OP setup. One advantage, (and there are many), even though its got two pistons, its still a single cylinder. One combustion chamber. Good for where you are allowed only one cylinder. Or for that matter twin cylinder racing. Four pistons.

[husaberg]

Okay, i found some RPM data.
348993

[lohring]

The single cylinder test I referenced was run at 3750 rpm. The speed was increased to 4000 rpm but some sleeve damage resulted, shutting down the program. The Bosh style fuel injection pump was a limiting factor at its maximum pumping volume. This is an engine with a 5.5 inch stroke.

Lohring Miller

[Peter1962]

I found this historic overview of the sleeve valve engine, interesting reading i think.
The engineers who build engines like that were ahead of their time.
file:///C:/Users/peter/AppData/Local/Temp/energies-14-00616.pdf


It is so sad, that after the war, the company destroyed the existing crecy prototypes... :no:

[Peter1962]

And this looks like a modern incarnation of the incredible Junkers Jumo from WW II : the Achetes 3 cylinder opposed piston engine. https://www.youtube.com/watch?v=UF5j1DvC954

[Peter1962]

This is interesting from start to end, but the real message is in the last 30 seconds of the video.
https://www.youtube.com/watch?v=zf6OH4iVUkY

[koenich]

Thanks Wobbly!
New head is now almost ready. I followed advice and focused getting water closer to the plug. Original plug hole o-ring was changed from axial to radial style and is now smaller diameter.

https://uploads.tapatalk-cdn.com/20210505/377f94a435633b1b40b66b646ca8656e.jpg
I changed the water flow through the MHR cylinder by closing the holes above the exhaust and opening a passage in the back of the cylinder in the insert. this requires relocating the water outlet to the front and a vent in the cover. helped quite dramatically with power stability over time...

[Flettner]

This is interesting from start to end, but the real message is in the last 30 seconds of the video.
https://www.youtube.com/watch?v=zf6OH4iVUkY

All diesels though. Completely different to a petrol OP uniflow.

[lohring]

I love that engine. I plan to learn CFD to help refine my design for a 60cc opposed piston engine. I wish someone had "discovered" opposed piston engines in my youth. Then the GM two stroke was the most advanced two stroke diesel. There would definitely have been a place then for a better design. Today, I'm afraid it's too late for new IC engines. Most of the work is toward electrics with battery and/or fuel cell power. A similar opposed piston engine by Eco Motors has died. They considered a gasoline small version. See below for their engine and ignition solution. That company is dead, and my friend who worked there has moved on. Achates does have some significant government contracts. I hope it works out.

Lohring Miller

348999349000349001349002

[TZ350]

2Stroke Stuffing.

<iframe width="560" height="315" src="https://www.youtube.com/embed/CaVssihAwkY" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

[ceci]

2Stroke Stuffing.

<iframe width="560" height="315" src="https://www.youtube.com/embed/CaVssihAwkY" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>



The only thing I agree with is his suspenders.


I keep thinking the same

[lohring]

If you use an efficient, screw compressor and can seal the exhaust with the disk, it can work. Will it really be better than the tuned pipe engine that's a lot simpler and lighter? People have tried almost the mechanical solutions to the two stroke's problems you can imagine. Today they only show an advantage in the big marine engines.

Lohring Miller

[jonny quest]

I'm just not a fan of anything other than naturally aspirated.

Really not even a fan of methanol or nitro.

[koenich]

His enthusiasm and go for it approach are admiring most of the time but this will be a nightmare to get somewhere near durable plus the blower will eat so much power to deliver enough air doubt it'll make it.

[Muhr]

2Stroke Stuffing.

<iframe width="560" height="315" src="https://www.youtube.com/embed/CaVssihAwkY" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Will it not take 9.86 kw to spin that pump 300cc 1.7bar at 17000k?

Feels like he needs to squeeze out a bit if he is to reach the world's most powerful 2-stroke

[Pagi]

Hello everyone,

this is my first message on Kiwibiker, i am very grateful to all of you who shared your knowledge ( sorry for my bad english....:rolleyes: ).
I have a question about the transfert duct, Mr Overmars, Wobbly, could it be beneficial to have the exit of the inner radius straight with the same angle like the outside radius on A and B transferts ? i ask the question, because i do not see it on the drawing of the rsa ducts .......

[Frits Overmars]

Hello everyone, this is my first message on Kiwibiker, i am very grateful to all of you who shared your knowledge ( sorry for my bad english....:rolleyes: ). I have a question about the transfert duct, Mr Overmars, Wobbly, could it be beneficial to have the exit of the inner radius straight with the same angle like the outside radius on A and B transferts ? i ask the question, because i do not see it on the drawing of the rsa ducts .......Welcome here, Pagi. The inner and outer radius of the RSA A-duct have the same exit angle, as indicated by the parallel upper yellow line and upper blue line in the picture below. But unlike the Honda transfer ducts, the RSA A-duct has no straight at its inner exit. A straight section here would inevitably lead to a reduction of the radius, and keeping the inner radius as large as possible is paramount for good flow.
By the way Pagi, your English is fine, but I can see one point for improvement. I do appreciate you addressing me as Mr. Overmars, but as I keep saying, Mr. Overmars was my beloved father. Just 'Frits' is fine by me :D.

[Pagi]

thank you very much 'frits':laugh::laugh:

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/Q_48YIOSedc" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>


In the Aprilia RSA the cylinder pressure at exhaust closure is about 2,6 bar. At TDC this pressure exceeds 80 bar as Wobbly mentioned, and 20° later it exceeds 120 bar. At exhaust opening it still exceeds 11 bar.

Alex is aiming to have the exhaust and transfers opening at the same or pretty much the same time. But it looks to me that 2Stroke Stuffings supercharged 2S engine will still need normal blow down time area. Because with the transfer and exhaust ports at the same height the supercharger would not develop enough pressure to hold the exhaust gases back from entering the transfer ducts/chamber.

My pick would be to have a normal Blow Down Time Area, an exhaust that assists with purging the cylinder but without the normal 2Stroke return pressure pulse and a rotary valve that closes somewhere before BDC when the cylinder pressure is at its lowest to trap the incoming clean supercharged air/fuel mixture.

The rotary valve timing can be adjusted to close when the pressure in the cylinder is at its lowest. The bonus is avoiding any hot exhaust gas and the pipe has assisted the supercharge to purge the cylinder. The rotary valve can open again well before TDC in fact any time after the piston has closed the exhaust port. Arranged properly there is no need for the rotary valve to see any real pressure on the blade or exhaust heat.

The rotary valve blade does not have to close Top Down either, it could close Bottom Up and in that way it would act like an exhaust port dam and as a bonus get cooled and lubricated by any blown through air fuel mixture.

The blade would also look different. Pretty much the reverse of a conventional blade. The blade parts shape would look much like the shape of the cut out in a conventional blade. It might even be possible to run a double sided blade at half speed to reduce power robbing drag.

At first I thought Alex's idea was crazy but now it looks very interesting, possible even, although I would probably look at a Turbo instead of a Supercharger just to get away from the superchargers power drag too.

[Vannik]

At first I thought Alex's idea was crazy but now it looks very interesting, possible even, although I would probably look at a Turbo instead of a Supercharger just to get away from the superchargers power drag too.

Supercharging a 2T for performance is not easy and the Aisin AMR300 is a Roots type, not a screw type so very inefficient. Attached is the best map for it I could find. It does not have a high pressure or high rpm rating, and in the top right hand corner is already absorbing over 5kW.

349082

I would not go this route, thermodynamics is against you.

[Muhr]

Supercharging a 2T for performance is not easy and the Aisin AMR300 is a Roots type, not a screw type so very inefficient. Attached is the best map for it I could find. It does not have a high pressure or high rpm rating, and in the top right hand corner is already absorbing over 5kW.

349082

I would not go this route, thermodynamics is against you.

Yes, that was an easier path than the one I tried. :weird:
http://www.jmcampbell.com/tip-of-the-month/2015/07/how-to-estimate-compressor-efficiency/

[SwePatrick]

I would probably look at a Turbo instead of a Supercharger just to get away from the superchargers power drag too.

Won´t work.
Turbo isn´t pumping at low rpm, therefor you have nothing that pumps into the cylinder.

This whole project is just a waste of time and money.

You have superior scavenging in a twostroke diesel, there are valvetrains that can take over 20000rpm, no need to re-invent the wheel.
But there are no compressor aviable that can pump from zero rpm and upwards except roots and screws.
And by that you might need throttle half open just to make it run on idle....
twostroke diesels don´t even have a throttle, they adjust the poweroutput and demand by the injectorpump.

If Alex only wouldn´t fly away in his thoughts and keep his feet on the ground he might acheive something, and by that don´t need to chop wood for a half year to heal his soul ;)

[TZ350]

Won´t work. Turbo isn´t pumping at low rpm, therefor you have nothing that pumps into the cylinder.

Yes. I hadn't thought about the issue with no pumping at start up. Good Point.

Alex is using a CVT transmission so once the engine is running it pretty much stays near a constant speed. Certainly it could be kept in the zone where the turbo is pumping.

Starting could possibly, be accomplished by a squirt from a compressed air bottle or a good puff from a blower.

Basically a decent blower or compressed air starter pack. A couple of dive bottles maybe. This is after all a land speed bike and once its running it is a one way trip across the salt before refuelling and doing a return trip. The blower or starter bottles could be stacked in the back of the support truck.

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/raT_8B7kP38" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Starting a pulse jet with a blower.

<iframe width="560" height="315" src="https://www.youtube.com/embed/NR5vczw5jZ0" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Starting a turbo jet with a blower.

Maybe the next thought experiment to try, is starting Alex's turbocharged two stroke with a decent blower.

[ceci]

A year ago we were analyzing this:


A 2 stroke...….no smoke and no expansion chamber


https://www.facebook.com/StrangeDevelopmentAndDesign/videos/277816313608614/

https://www.facebook.com/watch/StrangeDevelopmentAndDesign/

https://www.facebook.com/116160916434310/videos/569186610461804


https://www.youtube.com/watch?v=ZhqFbFGP5hs

What is the difference: which is better the disc valve?

[lohring]

Eco Motors ran turbochargers with electric motors.

349083

Formula One has a motor/generator in their turbos. I have one of those motors, but I have no idea how it's hooked up. Today there are low cost, high power model motors that could easily spin up a turbocharger. The model turbojets (https://www.turbinesolutions.co.uk/wren-turbines-by-ts)use an electric start system.

Lohring Miller

[ceci]

At the intake it is clear that the rotary disc valve wins over the cylindrical rotary valve (only QUB has operated at high levels).
In the exhaust the same thing or the opposite happens, which of the two solutions is better, Alex with a disc valve or StrangeDevelopment with a cylinder valve.

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRp8Z6tcg25iBRNVOrDs8Ye1a-xsAWWGIuanA&usqp=CAU

[Frits Overmars]

At the intake it is clear that the rotary disc valve wins over the cylindrical rotary valve (only QUB has operated at high levels).
In the exhaust the same thing or the opposite happens, which of the two solutions is better, Alex with a disc valve or StrangeDevelopment with a cylinder valve.I would not say that QUB has operated at high levels with the half-speed drum inlet valve in their QUB-250; it produced 42 hp at a time when the disc-valve MZ-250 produced 60 hp, despite the very modest financial possibilities in the German Democratic Republic, compared to the deeper pockets of Queens University Belfast.
However, for a valve working in hot exhaust gases I would prefer the drum type, like StrangeDevelopment is doing.

[ceci]

I would not say that QUB has operated at high levels with the half-speed drum inlet valve in their QUB-250; it produced 42 hp at a time when the disc-valve MZ-250 produced 60 hp, despite the very modest financial possibilities in the German Democratic Republic, compared to the deeper pockets of Queens University Belfast.
However, for a valve working in hot exhaust gases I would prefer the drum type, like StrangeDevelopment is doing.

42CV was already delivered by OSSA of SANTIAGO HERRERO and was single cylinder and air-cooled

[wobbly]

I tend to agree with SwePatrick , the vast majority of people that we see getting into developing a " new " way of operating a 2T , cant manage to build one that operates
at the currently accepted SOTA levels , so are doomed from the getgo.
I fear Alex is going to end up like NoLuc - continually making huge promises his ability cant match in reality.

[ceci]

However, for a valve working in hot exhaust gases I would prefer the drum type, like StrangeDevelopment is doing.

I may be wrong, but I think we share the same choice, we prefer physical barriers to solid barriers for the containment of loss of load due to the exhaust

[TZ350]

I tend to agree with SwePatrick, the vast majority of people that we see getting into developing a " new " way of operating a 2T , cant manage to build one that operates at the currently accepted SOTA levels , so are doomed from the getgo.
I fear Alex is going to end up like NoLuc - continually making huge promises his ability cant match in reality.

There are some issues here. Alex's stated aim is to build the worlds most powerful 50cc two stroke and prove it on the Bonneville salt flats.

Alex has already made a pretty successful conventional 2S. Just some of the things he has done along the way. He has made his own dyno to test his original engine and on going development work. He then moved on to exploring the 24/7 concept. He made his own cylinder plating system to plate his own home made cylinder. A cylinder that has a layout based on the Aprilia RSA and his knowledge of modern two stroke design.

Then super wide exhaust ports to acheve the port time area needed to get to the next level. To get the big ports he had to go to new ideas about ring and piston design. He built his own CNC maching centre to make things for this project. Now he is musing about better ways of improving the BMEP of his creation. Like Burt Munro, maybe Alex will not totaly realise his dream on the salt. But like Burt, Alex's efforts, energy and dedication to the cause are sure a cut above most mortals.

If Alex was a Bucket racer here in New Zealand we would all be in awe of his energy and inventiveness. And is the reasion I post his YouTube clips. Basically he is doing what I wish I could. I guess a lot of us would have loved to do what he is if we had been talented or skilled enough.

Un like secrative NoLuc, all take, boastful, with no generosity at the dinner table. Alex has always been open about his dream, what he is doing, how he is doing it, his progress, his successes and failures and is why he is welcome here. Maybe it all wont work out succesfully for him but he does make an interesting dinner guest.

[Frits Overmars]

Unlike secrative NoLuc, all take, boastful, with no generosity at the dinner table, Alex has always been open about his dream, what he is doing, how he is doing it, his progress, his successes and failures and is why he is welcome here. Maybe it all wont work out succesfully for him but he does make an interesting dinner guest.Amen to that. I couldn't agree more :niceone:.

[wobbly]

I fully agree with you as well TeeZee , I wish him the best of luck - but get frustrated when he bounces around from one tangent to the next instead of fully exploring one avenue
and proving/disproving its validity.
The reverse L ring in a 100% bore / port is the best example .
I know it works perfectly , I was there , and it was me who suggested for Makr to try it in his new two piece piston design.
But this somehow ended up as a flat ring with a retaining hole that failed instantly - and resulted in the concept being totally dumped.
In this case it wasnt the concept that was flawed , it was the execution.

[breezy]

i really enjoy Alexs you tube 2stroke stuff... hes built up a good bit of kit and learnt how to use it... maybe with supercharging he could have more controlled exhaust ports and more radial transfers in the conventional way.:calm:

[Muhr]

Quite an interesting site on compressor on small engines, especially if you like old engines. https://www.elsberg-tuning.dk/supercharging.html

[Condyn]

Here is something I whipped up today. My plan is to use it as a tool when changing stroke and rod length to find what piston and or spacer is necessary. It has a slotted hole so the carriage bolt that is brazed to an extra rod pin can slide to adjust the stroke. Similar to Jan Bros killer spreadsheet, the "old" engine can be documented on the tape before increasing the stroke and rod. It is very crude in version 1. The idea is to have a quick visual of the situation. Doubt this is the first of its kind, but I figured I would share with you kind gentlemen.

[lohring]

Quite an interesting site on compressor on small engines, especially if you like old engines. https://www.elsberg-tuning.dk/supercharging.html

I don't get the feeling that that author really understands the concept of two stroke supercharging. As I've said many times, you can supercharge a two stroke by raising both the intake and exhaust pressure. A tuned pipe does this as does a turbocharger. Both have limitations. Of course you can do this with a mechanical supercharger and an exhaust valve. I would pick an efficient screw compressor over a Roots blower if you want significant boost. The entire cycle pressure can be raised in this way.

This same issue applies to Stirling engines. There the cycle can be closed in a chamber. At atmospheric pressure, the cycle needs a really big engine for significant power. You need to raise the cycle pressure to thousands of psi in a commercial engine. This creates seal issues, especially when hydrogen is the working fluid. Even so, engines with a generator enclosed in the pressure vessel are being used in several current applications (https://en.wikipedia.org/wiki/Kilopower).

Lohring Miller

[andreas]

Regarding turbocharging of two stroke engines.

Lennarth Zanders work.

Power up to ~70 hp was seen on dyno (125cc) as I understand reading the paper.

https://www.sae.org/publications/technical-papers/content/2021-01-0642/preview/

Lennarth Zander, really nice fellow lives close to me, I've visited him a couple of times in educational purpose. It isn't enclosed in the article what performance this engine had, but the engine before was a tzr 125 close to standard and it made 55 hp at the sprocket I think.

[TZ350]

.
<iframe width="560" height="315" src="https://www.youtube.com/embed/Oxj_OAb5bqk" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Turbocharged Yamaha TZR125 Two Stroke being run up on the dyno.

[andreas]

Yes, that is him talking in the other, am6 video.

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/gv377_f3cvU" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Turbo 50cc two stroke being dyno tested.

[ken seeber]

Well, the DCI (Direct Cylinder Induction) thing is moving slowly along, but still moving.

Finally got a piston from some joint over here. :laugh:

Made up some cover plates to go over the entry flange faces, one with a pressure tapping. The gauge, which shows both +ve and -ve pressures, will be connected to this tapping. The broad plan is that the engine will be run up with just the B ports only, the original A ports being converted into the DCI intake ports.

The big hope is that the gauge will show -ve at some point in the rev range. Nary a supercharger in sight.

More to come.

349104

[Vannik]

.
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Turbocharged Yamaha TZR125 Two Stroke being run up on the dyno.

This work is done by Lennarth Zander, a Swedish engineer that works at Scania. Even though the video is old, I understand he has resurrected this project and is doing his PhD at Chalmers University of Technology. The interesting thing he does is between the tuned pipe and the turbine he fits an oxidation catalytic converter which reacts with the unburnt oxygen and the fuel and ups the temperature quite a bit to improve the turbine running. The converter works so well he has to control the amount of gas being converted to prevent temperature damage to the turbine.

One of the issues with a turbine after the tuned pipe is the loss of temperature, this reverses that for no extra penalty, the fuel and oxygen is already there.

This is partially how I would do the "Worlds strongest two-stroke".

[SwePatrick]

The turbosystemZander has engineered is nothing to use in real life though.
It takes ages for the catalytic to build heat/pressure.

A guy in Sweden has copied Zanders system and runs it on an 100cc moped engine, it has dynoed nice numbers(from my mind ~58hp), but it never hits the track for some reason....(he has run it in an earlier version)
The reason is he needs to make either a HUGE LONG(about 3-5minutes long) burnout or stand in the pit on his rolling pad and run engine for a loooong time(he stood about 10 minutes) to light up the cat.
Then hit the lineup and wait for staging, while the cat cools down....

In bonneville it might work thou ;)

[SwePatrick]

Found a video:


https://www.youtube.com/watch?v=DU29wgvJFHk

[Niels Abildgaard]

This work is done by Lennarth Zander, a Swedish engineer that works at Scania. Even though the video is old, I understand he has resurrected this project and is doing his PhD at Chalmers University of Technology. The interesting thing he does is between the tuned pipe and the turbine he fits an oxidation catalytic converter which reacts with the unburnt oxygen and the fuel and ups the temperature quite a bit to improve the turbine running. The converter works so well he has to control the amount of gas being converted to prevent temperature damage to the turbine.

One of the issues with a turbine after the tuned pipe is the loss of temperature, this reverses that for no extra penalty, the fuel and oxygen is already there.

This is partially how I would do the "Worlds strongest two-stroke".

See the powerpoints here

https://research.chalmers.se/publication/522865/file/522865_Fulltext.pdf

[SwePatrick]

Here are a pic of what's what in one of Zanders project:

349105

And here´s a video of it, take notice about the lag before the turbo inlet get any heat.
Notice how he let´s off the throttle when headertemp is getting north of 650c, it is actually not in control.

https://www.youtube.com/watch?v=zybsu4Mwato

[SwePatrick]

I actually tested turbo myself on my 212cc kawasaki engine, but i set it up different.
I used a draw through system(turbo between the reed and the carb.
No catalythic converter as i had a bigger engine.

I tuned the pipe to about 7500rpm, to get some exhaustmasses early and relied on the turbo to do the scavenging in the upper rpm band.
It actually worked really nice, but the piston couldn´t take it, i dynoed 96hp after just a couple of pulls.
But i gave it up as i figured the engine couldn´t take it in the long run, and needed constant piston service after every run on the strip.
It was a bit laggy, but spooled quite nicely in higher gears.

One importent thing is to balance the pressure delta over the inlet and the outlet.
If making it not differ from an NA engine the engine never know it´s been boosted.

This is impossible to reach with supercharger, thereby Alex is fiddeling with rotating disc in exhaust.

[andreas]

Regarding turbocharging of two stroke engines.

Lennarth Zanders work.

Power up to ~70 hp was seen on dyno (125cc) as I understand reading the paper.

https://www.sae.org/publications/technical-papers/content/2021-01-0642/preview/

Pardon, it says right in the beginning 400kw/liter, =67 hp.

If there is too much lag in this engine, maybe it is possible to use the system used in rally cross cars and maybe elsewhere, I forgot what it's called, but it burns fuel in front of the turbo when the engine isn't making enough pressure itself.

[Muciek]

Normal two step used these days in cars (delaying ignition a lot ) might not be best for bike? This one was used years ago by subaru
https://www.youtube.com/watch?v=ms3U7Ztoip8

[Norman]

Pardon, it says right in the beginning 400kw/liter, =67 hp.

If there is too much lag in this engine, maybe it is possible to use the system used in rally cross cars and maybe elsewhere, I forgot what it's called, but it burns fuel in front of the turbo when the engine isn't making enough pressure itself.

Maybe one of these: https://en.wikipedia.org/wiki/Antilag_system

Here is another design version for a rotational exhaust valve.

[Frits Overmars]

This work is done by Lennarth Zander.... between the tuned pipe and the turbine he fits an oxidation catalytic converter which reacts with the unburnt oxygen and the fuel and ups the temperature quite a bit to improve the turbine running.
...the exhaust gases contain both air- and unburned fuel (HC) which can be converted to heat upstream the turbine using an oxidation catalyst, hereby also named afterburner.Fuel need not be a problem; one can inject as much fuel in the exhaust system as one likes. But what about oxygen?
In his paper ( https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131186140&posted=1#post1131186140 ) Lennarth Zander only states that the exhaust gases contain air; there is no explanation how this air could pass through the combustion engine without all of its oxygen being consumed.
Is he deliberately running a very lean mixture? That would not make the piston of a turbocharged engine very happy. Have you got information beyond the paper, Neels?

[ken seeber]

Maybe one of these: https://en.wikipedia.org/wiki/Antilag_system

Here is another design version for a rotational exhaust valve.

Interesting stuff. The valve shaft, rotating at crank speed, also doubles as a balance shaft.

349109

The good news is also that BRP are still thinking about 2 strokes.

[Vannik]

Is he deliberately running a very lean mixture? That would not make the piston of a turbocharged engine very happy. Have you got information beyond the paper, Neels?

No extra info, sorry.

[andreas]

Fuel need not be a problem; one can inject as much fuel in the exhaust system as one likes. But what about oxygen?
In his paper ( https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131186140&posted=1#post1131186140 ) Lennarth Zander only states that the exhaust gases contain air; there is no explanation how this air could pass through the combustion engine without all of its oxygen being consumed.
Is he deliberately running a very lean mixture? That would not make the piston of a turbocharged engine very happy. Have you got information beyond the paper, Neels?

"The afterburnerassistedturbocharger system makes it possibleto ”over scavenge” the engineto lowerthe exhaustport temperaturewhilethe pre turbinetemperaturecanbe maintainedat a decent800 degCtemperature. Not bad for an engineputting outaround50 [kW]."

Frits, maybe this is what he means. Copy paste didnt work so well, but it's to be found further down in the text.

[SwePatrick]

It pops and bangs a little before it´s cleaned up, then it pops and bangs when it hits the revlimiter.(13000rpm)
I sat down in seat and had only about 12psi in rear tire to get some traction on 4th gear(i actually tested a thing)
The smoke laid thick in the house for a couple of hours, but burnt rubber is a good smell ;)


https://www.youtube.com/watch?v=SzbHj6-CJSQ

I tested new carb jetting as i had a HUGE hole in fuel delivery just before it hit the pipes, now it seems good.
Special grinded the metering rods and changed the emulsionpipes.

[Norman]

"The afterburnerassistedturbocharger system makes it possibleto ”over scavenge” the engineto lowerthe exhaustport temperaturewhilethe pre turbinetemperaturecanbe maintainedat a decent800 degCtemperature. Not bad for an engineputting outaround50 [kW]."

Frits, maybe this is what he means. Copy paste didnt work so well, but it's to be found further down in the text.

I think that he in this particular set up is using an afterburner and "port injection" (not TPI) or carburator (in actual test). Then he states that an oxidation catlyst can be used to increase exhaust temperature before turbine if the exhaust/short circuit is lean/air. I am thinking that if a DI system is used, the short cut will be mostly air.
On the set up picture from the Charlmers presentation it looks as if they are using one intercooler and then a water cooled charge air section. I can imagine it is important to keep the inlet temp down. The quite large compressor to carburetor intake tract on the test set up must also affect pressure build up. Should be quite easy to optimize by using one charge air cooler (small) and a low temperature radiator circuit with a dedicated pump (of course all about where the engine is to be used)
Interesting concept and of course still room for much optimization.

[Frits Overmars]

"The afterburnerassistedturbocharger system makes it possibleto ”over scavenge” the engineto lowerthe exhaustport temperaturewhilethe pre turbinetemperaturecanbe maintainedat a decent800 degCtemperature. Not bad for an engineputting outaround50 [kW]."
Frits, maybe this is what he means. Copy paste didnt work so well, but it's to be found further down in the text.If I understand you correctly, the engine runs on a normal air-fuel mixture (Lambda somewhere between 0,8 and 0,9) and the air that makes it to the afterburner was blown straight through the engine before exhaust port closure. That sounds plausible and simple :niceone:.

It reminds me of a proposal by Keith Duckworth (or was it Colin Chapman?) back in the day when two-strokes were not yet forbidden in Formula 1. He envisaged a two-stroke engine with an extremely high exhaust timing, feeding a turbocharger that was geared to the crankshaft. Whether the crankshaft was going to drive the turbo or the other way around did not matter; what mattered was the power generated by this compound layout. I don't know why Duckworth did not take the idea further. Maybe it was the specific fuel consumption that put him off, or maybe he got the rulebook thrown at him.

[Muhr]

I guess it's not a regular catalyst we'm talking about? To me, a catalyst is just a lump of stainless steel with honeycomb structure dipped in palladium or something similar. Wondering if he is thinking of something similar below.
https://patentimages.storage.googleapis.com/7a/dd/ed/e487f5293cc08a/US3220179.pdf
https://www.researchgate.net/publication/325799021_Catalytic_Oxidation_of_Synthesis_Gas_on_ Platinum_at_Low_Temperatures_for_Power_Generation_ Applications/fulltext/5b25074f458515270fd386d7/Catalytic-Oxidation-of-Synthesis-Gas-on-Platinum-at-Low-Temperatures-for-Power-Generation-Applications.pdf?origin=publication_detail

[andreas]

If I understand you correctly, the engine runs on a normal air-fuel mixture (Lambda somewhere between 0,8 and 0,9) and the air that makes it to the afterburner was blown straight through the engine before exhaust port closure. That sounds plausible and simple :niceone:.

It reminds me of a proposal by Keith Duckworth (or was it Colin Chapman?) back in the day when two-strokes were not yet forbidden in Formula 1. He envisaged a two-stroke engine with an extremely high exhaust timing, feeding a turbocharger that was geared to the crankshaft. Whether the crankshaft was going to drive the turbo or the other way around did not matter; what mattered was the power generated by this compound layout. I don't know why Duckworth did not take the idea further. Maybe it was the specific fuel consumption that put him off, or maybe he got the rulebook thrown at him.

Colin Chapman it seems. Was it a uniflow? I found random discussion here: https://www.f1technical.net/forum/viewtopic.php?f=4&t=10966&start=15

[SwePatrick]

I guess it's not a regular catalyst we'm talking about? To me, a catalyst is just a lump of stainless steel with honeycomb structure dipped in palladium or something similar. Wondering if he is thinking of something similar below.
https://patentimages.storage.googleapis.com/7a/dd/ed/e487f5293cc08a/US3220179.pdf
https://www.researchgate.net/publication/325799021_Catalytic_Oxidation_of_Synthesis_Gas_on_ Platinum_at_Low_Temperatures_for_Power_Generation_ Applications/fulltext/5b25074f458515270fd386d7/Catalytic-Oxidation-of-Synthesis-Gas-on-Platinum-at-Low-Temperatures-for-Power-Generation-Applications.pdf?origin=publication_detail

As i understand, it is just regular ones, but small cores.

[Vannik]

A "normal" catalytic converter as on gasoline fueled passenger cars are "three way" catalytic converters requiring stochiometric AFR.

The oxidation catalytic converter is a different type that operates in an excess level of oxygen, typically found on diesel engines.

[41juergen]

A "normal" catalytic converter as on gasoline fueled passenger cars are "three way" catalytic converters requiring stochiometric AFR.

The oxidation catalytic converter is a different type that operates in an excess level of oxygen, typically found on diesel engines.

And the trick is how to use the washcoat to get the fine precious metal particles distributed and "in place" during the catalysts life time... :msn-wink: