ESE's works engine tuner

[RAW]

As far as I know all 250 cc Superkart-twins use that type of inline engine. But those are all counter-rotating simultaneously-firing twins, perfectly balanced with 100% balance factor for each crankshaft. The discussion with Wobbly was about inline twins that were not counter-rotating and/or not simultaneously-firing.
Did Dolph say anything about those cases?

Hello Frits, sorry I failed to provide adequate information
I was referring to taking an in-line engine such as the Rotax 256 or any of the modern variants such as the ( BRC, DEA, PVP, FPE & or VM ) counter rotating engines and phasing the crankshafts & firing to be 180* as opposed to the Big Bang configuration for use in a superkart.
My conversations with Dolph upon this concept & his subsequent crankshaft balance equations upon this with the crankshaft data I supplied him, he suggests that a reworking of the crankshafts counterweights would produce a satisfactory configuration by which performance in both power & component longevity would be not detrimental against the standard configuration.
I have touched upon this subject with yourself on the pit lane forum previously,
I like the idea of something different ( a screener engine ) however if there is to be a power & or reliability loss I do not see a point to it,
You have an elegant way of explaining thing as an integrated unit for itÂ’s intended use that a layman can envisage, would you enlighten me given your knowledge & intellect upon this concepts pros & cons etc.

[RAW]

[QUOTE=ken seeber;1131182602]Rick,
I seem to remember someone, was it Jan, say they were laser welded and very expensive. Assuming they were hollow, then they must have been made in multiple parts which are then welded, pressed or bonded together. Maybe there is some other magic out there though. I think Wob’s design is utilising the standard pin, so some form of retention is required and, in his case, no distortion of the OD of the pin

Hi Ken, I have several of the Pankle pins ( non stepped variant ) Inspection / reverse engineering informs me that laser welding was not used with the flat ended versions, perhaps the stepped ended variant was however I doubt it given what I have seen & understanding the cost of manufacturing a pin the way Pankle has Vs a laser process.
Subsequent usage & inspection at regular periods of the Pankle pin shows the superior performance of this pin over numerous other manufacturers pins. As I indicated there is more to the Pankle pin than the closed ends that is responsible to any performance gains in my opinion.

[Frits Overmars]

Hello Frits, sorry I failed to provide adequate information
I was referring to taking an in-line engine such as the Rotax 256 or any of the modern variants such as the ( BRC, DEA, PVP, FPE & or VM ) counter rotating engines and phasing the crankshafts & firing to be 180* as opposed to the Big Bang configuration for use in a superkart. My conversations with Dolph upon this concept & his subsequent crankshaft balance equations upon this with the crankshaft data I supplied him, he suggests that a reworking of the crankshafts counterweights would produce a satisfactory configuration by which performance in both power & component longevity would be not detrimental against the standard configuration. I have touched upon this subject with yourself on the pit lane forum previously, I like the idea of something different ( a screener engine ) however if there is to be a power & or reliability loss I do not see a point to it. You have an elegant way of explaining thing as an integrated unit for itÂ’s intended use that a layman can envisage, would you enlighten me given your knowledge & intellect upon this concepts pros & cons etc.

The left side of the left-hand picture shows the classic counter-rotating simultaneously-firing inline twin. When both pistons are in TDC or in BDC, their inertia forces V are 100% balanced by the forces B from the crank web masses. This requires a 100% balance factor per crankshaft, as the heavy-metal concentrations in the photograph demonstrate.
When both pistons are about halfway down, their inertia forces V are zero (no acceleration) and the big crankshaft forces B cancel each other out. That's great: no free forces and no vibration in any direction.

If you time these crankshafts at 180°-firing as in the right side of the left-hand picture, at the pistons-halfway position the forces B both act in the same direction; they reinforce each other, and the engine will vibrate strongly in the horizontal plane, though it will still be vibration-free in the vertical plane.

You can reduce the forces B and so reduce the horizontal vibrations, but then the vertical forces V will no longer be completely compensated by the forces B, like in a single-cylinder engine without a balance shaft, where you accept some horizontal vibration in order to reduce the vertical vibration, or vice versa.

The difference between a single and a twin is that the vertical forces V in this 180°-firing counter-rotating inline-twin counteract each other, no matter how big they are, so you could give this engine a zero % balance factor, thus completely eliminating the forces B and their horizontal vibration. This only leaves a torque, caused by the vertical forces V, multiplied by the horizontal center-to-center distance between the two cylinders, which is trying to rock the engine around its transverse axis.
In this respect, the situation is similar to a 180°-firing transverse twin without a balance shaft, where the unbalanced parts of the V-forces are rocking the engine around its longitudinal axis, while the B-forces are rocking it around its vertical axis.

Maybe the vibration of this resulting torque, rocking the 180°-firing inline engine around its transverse axis, is acceptable if the smoother engine torque of the 180°-firing permits the use of softer tire compounds. If we didn't have this damned Covid I'd go and have a cup of coffee with Dolph. It's always a joy to sharpen our minds together.

[Muhr]

Rick,
I seem to remember someone, was it Jan, say they were laser welded and very expensive. Assuming they were hollow, then they must have been made in multiple parts which are then welded, pressed or bonded together. Maybe there is some other magic out there though. I think Wob’s design is utilising the standard pin, so some form of retention is required and, in his case, no distortion of the OD of the pin

If the circlip is to be accessed to allow pin removal, then one could assume there would need to be sufficient annular gap to achieve this. Despite its end having a spherical and tight clearance to the bore, close. It could never be as good as a form fitting pin or plug. I believe Wob is on the case to make a comparison.

Any form fitting pin or plug needs accurate indexing and axial location.

Can't think of any other way the pin could change the performance, other than less short circuiting, change of mass or sealing off the central volume of the pin.

https://www.mondokart.com/en/engine-...in&results=147

Attachment 348597Attachment 348598

I wonder where the first photo comes from?

I'll cut one to pieces when I get home to try to understand what's so special about a Pankel

[andreas]

Frits, I liked your pipe article series, maybe there can be a collectively done translation of it, but now I cant find it. It's gone?

[wobbly]

Answers to a few questions - the best way to route water , and this has been tested on a KZ kart engine , up to a TZ750 classic racer , is to pump the cold water in over the boost port.
This then flows forward over the transfers , then picks up the greatest heat load around the Exhaust duct , then passes up into the head.
The head is a catch 22 in that you want to cool the plug thread and squish area as much as possible , but keep the comustion chamber only , hot , to reduce throwing burn energy away via a big temp delta to the water.

I have dyno tested several versions of pin plugs in KZ engines , the latest being the laser welded tophat type , that allows stock pins and clips to be retained.
The first test was a full piston pin hole cover , with indexing , in plastic Torlon that utilised the clip for retention ( thanks Ken ).
This was worth about 1/2 Hp on a stock Aux port that had little port linking anyway.
But with very much enlarged Aux ports ( around to bore center ) the difference was closer to 2 Hp average.
But after two race meetings the lack of lubrication access from the transfer flow , into the piston /pin bearing area , caused the pin surface to turn blue.

Next test was a simple cap , laser welded slightly inside the pin end , this had maybe 0.25 Hp on a stock cylinder and 0.75 Hp down low on a big port cylinder ( they fell out as well ).
So caps operating just as a method of removing the pin interior volume from the system , worked , but achieved little.
Now I have just tested the top hat pins , beautifully laser welded , and these , with a new design big port cylinder were worth between 3.5 @ 10.000 and 1.5 Hp @ 14000 - no contest.
In the weekend just gone this traslated into 0.3 sec lap time reduction.

Re the Tandem twin balancing . Frits has detailed it all well as he would . Its impossible to run a Tandem at 180 , Kawasaki did it first here in NZ testing , the bike was absolutely impossible to ride , as Ballingtons/Mamola's
hands and balls went to sleep , and worse , it fell to bits.
A balance shaft is needed , but this adds inertia plus friction , and the 180 screamer firing achieves nothing.
The best layout ( for a bike ) I believe is a big parrallel twin ( KTM 250 GP ) but turn the cylinders around , and then add twin RV across the front driven by the balance shaft , needed anyway for 0-90 firing.
Using Flets RV gib system , then adds a huge bunch of power , and can then be used to delete the carb slide. Mk2 TPI will be designed into the castings , once TZ350 tells me how to control the ECU on a road race engine.
Dr Henise is CAD drawing this engine around my EngMod and sketch files as we speak.

[husaberg]

It would be intersting to find out why the Kawasaki designers used a 180 firing order for the KR250 tandem road bike.
Maybe they liked the sound better, but they must have had a reason?



Long term with a big bang contra-rotating primary does that mean the primary gear wears faster?

[SwePatrick]

The best layout ( for a bike ) I believe is a big parrallel twin ( KTM 250 GP ) but turn the cylinders around , and then add twin RV across the front driven by the balance shaft , needed anyway for 0-90 firing.
Using Flets RV gib system , then adds a huge bunch of power , and can then be used to delete the carb slide. Mk2 TPI will be designed into the castings , once TZ350 tells me how to control the ECU on a road race engine.
Dr Henise is CAD drawing this engine around my EngMod and sketch files as we speak.

Yamaha 3ma engine is equipped with balanceshaft and have the cylinders turned 180 degrees, also an alternative?

[Frits Overmars]

... usage & inspection at regular periods of the Pankl pin shows the superior performance of this pin over numerous other manufacturers pins. As I indicated there is more to the Pankl pin than the closed ends that is responsible to any performance gains in my opinion.

I'll cut one to pieces when I get home to try to understand what's so special about a Pankl

Found this in my Aprilia documentation and I wouldn't be surprised if this drawing originated on a Pankl drawing board.

Frits, I liked your pipe article series, maybe there can be a collectively done translation of it, but now I cant find it. It's gone?

I'm glad you liked them Andreas, but those articles are from 1978 / 1979, so their value today may be historical rather than technical. Most of what I wrote back then is still true (that is the nice thing about the laws of physics as compared to politics) but with today's knowledge I feel that some important aspects were incomplete, so I would not bother translating it myself now. And as the perfectionist that I still am,
I probably wouldn't be satisfied with a translation by someone else. That is the downside of perfectionism: you think there is always room for improvement, which is a perfect recipe for a burnout.
Been there, and once is enough.

[andreas]

Right, got it.

[Muhr]

Found this in my Aprilia documentation and I wouldn't be surprised if this drawing originated on a Pankl drawing board.

It turned out to be something like this. unfortunately no magic dust when it was opened. But appears to be welded in gas, such as a chamber or laser given the lack of signs of high temperature on the inside

[SwePatrick]

You probably need to weld it inside a gaschamber as when you trap air inside it might be hard to seal up, as air want´s to escape due to it gains volume when hot, and thereby became a problem getting the last dime done.

[katinas]

Another interesting pin with usual conical shape on the both sides, but with approx 1.5 mm steps at the ends. This pin from Yamaha 500 latest 2002 version OWK1 with Honda style exhaust. Marks on piston shows that sides of exhaust windows not overlapping with piston pin hole.

[Flettner]

My tandem engine, same direction, 180 firing, was smooth enough. BUT the torsional loads on the small drive gears were too high. Kept busting gears. So I gave up and just built a 180 degree, case reed, parallel twin with a balance shaft. Smooth, reliable and flyable.

But now I'm thinking V twin version of this, not for aviation though. https://youtu.be/mS0cyt7F9js,

[TZ350]

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More Two Stroke Stuffing.
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