ESE's works engine tuner

[philou]

I have to move the pin on a piston ring.

which difference in diameter between the hole and the pin for proper maintains ?

0,1 mm it's correct ?

[Frits Overmars]

Does the wet crankcase prevent the cylinders pointing downwards?

Not more than on any radial four-stroke engine. In short: No.

[MotleyCrue]

Quote " the volume of mixture transferred to the cylinder at BDC is no greater than the cylinder swept volume " .
WRONG.
I posted a few pages back answering a question about how much volume is going thru the transfer ducts into the cylinder.
There have been cases I have seen of a Delivery Ratio number of 1.3, this indicates 30% more volume is being inducted and deposited in the
cylinder than the numeric swept volume.
But as the scavenging and trapping efficiency are both less than unity, some of this ends up as pollution in the Ex duct - despite the stuffing
effect of the rear cone area contraction.

Quote " The pressure in cylinder at BDC is same as pressure under piston at TDC, so no supercharging."
WRONG AGAIN.
The pipe diffuser is pulling a huge depression on the Ex port at BDC, thus the pressure in the cylinder is LOWER than the case pressure or we would have no flow
due to no pressure ratio delta - we have pipe effect induced supercharging if you like.
Only lawnmowers use the case pressure to transfer A/F into the cylinder.

I think the original point being made is that there is no positive displacement supercharging for a non-stepped piston.

[Dutch Fisher]

I didn't see any definition of supercharging in the CIK-FIA karting regulations.

Indeed the best we get is Article 2.6.1 Para.3
"The engine shall not comprise a compressor or any supercharging system"

Very enlightening, the use of the word system is somewhat open-ended.


Here's a revision of my previous question with a couple of well placed extra characters that escaped my last attempt.

Is a primary CR ratio of 1.8:1 or greater considered supercharging?

[wobbly]

Surely the logic that the current engines all have a primary CR near 1.3 means that at 1.8 ( a tiny case = more compression ) means it
is no different.
My belief is that the Ryger is using "direct transfer technology " ( if they were Japs not Dutch it would already be called DTT ) ie some of the 11 transfers allow direct passage of flow from the inlet
straight into the cylinder without having to go thru any connecting volume.

[husaberg]

My belief is that the Ryger is using "direct transfer technology " ( if they were Japs not Dutch it would already be called DTT ) ie some of the 11 transfers allow direct passage of flow from the inlet
straight into the cylinder without having to go thru any connecting volume.

That's what I think to due to the ports Kadenacy effect and intake flow inertia.

. The Kadenacy effect depends on a pressure difference over both sides of a tube. This difference will accelerate a mass of gas in the tube until the pressure difference is zero. Because of inertia the mass will keep on moving, causing a low pressure at the former high-pressure side of the tube. This low pressure sucks in ambient gas. That's all folks..

That coupled with a very high delivery ratio

[WilDun]

There have been cases I have seen of a Delivery Ratio number of 1.3, this indicates 30% more volume is being inducted and deposited in the cylinder than the numeric swept volume.

Seems to me that trying to fit all this into the competition rulebooks in a fair manner is a bit of a nightmare! but then, I know that Frits will be aware of that!

Looking at it from the point of view of two strokes in general, I reckon it all looks very interesting, as there are no impediments such as the banning of supercharging as in competition engines , (which seems to exist anyway without being noticed and is very difficult to quantify).

Then there will be the battle with the big four stroke boys, firmly battened down and securely attached to their perch! I think it will all be very exciting!

[Frits Overmars]

Seems to me that trying to fit all this into the competition rulebooks in a fair manner is a bit of a nightmare! but then, I know that Frits will be aware of that!

You bet. I've been formulating technical regulations for various types of motor sport during the last couple of decades, but before that I practiced reading between the rulebook lines all my life. And the CIK karting technical regulations are a joy.
Small example: in some classes it is not allowed to add ports to the cylinder. So what are ports? Let me take you on a wonderful trip through the rulebook....

1.2.3.2 – Ducts or passages
Ducts or passages are cylindrical or cylindrical-conical ele­ments allowing the passage of gases....

1.2.3.3 – Inlet or exhaust port
A port is composed of the intersection of the periphery of the cylinder and the inlet or exhaust duct....

Suppose I add two auxiliary exhaust channels with rectangular cross sections. Since they are neither cylindrical nor cylindrical-conical, they do not qualify as ducts.
So their intersections with the periphery of the cylinder do not qualify as ports either.
Don't you love it?

[ken seeber]

I have to move the pin on a piston ring.

which difference in diameter between the hole and the pin for proper maintains ?

0,1 mm it's correct ?

Philou,
The pins we use are around 8 long and dia 1.55. They have a taper on one end and also have a longitudinal slot to prevent any hydraulicing ?(from say coolant) when bring pressed in. We drill the piston with a 1.5 drill, giving a 0.05 interference. The actual force to press the pin in, at a guess, is around 800 - 1000 N.



Frits,
Agreed, the definition of passages/ports/ducts is confusing, but always happens when some new technology(in any field) comes along that is outside the conventional understanding and the associated rules, regulations and laws..
Irrespective, I am starting to think that the Ryger system is a form of direct air inlet system, and just used the below piston volume for starting and possibly some small contribution to the dampening of the piston downward piston inertia forces. The routing of the passages etc being necessary to route all the ingested air to pass thru the obligatory 30 carb.

[Frits Overmars]

Frits, Agreed, the definition of passages/ports/ducts is confusing, but always happens when some new technology(in any field) comes along that is outside the conventional understanding and the associated rules, regulations and laws..

Ken, the above-quoted CIK-rules are still the same as they were 10 years ago .

[jonny quest]

Usually good rulebooks also include

*and anything may be deemed legal and or unlegal by sanctioning body at any time.

[WilDun]

That is a very thought provoking photo Ken! - is it for real? or ...........what?

[ken seeber]

Ken, the above-quoted CIK-rules are still the same as they were 10 years ago .

Frits, that's the point. They have a responsibility to keep up with the times and any new technologies. Their KZ rules and they are filled up with all sorts of ambiguities, possibly due to the translation, but confusing nonetheless. Rules are always going to be challenged. How's the world to advance if this is not the case, but if the rules are vague then it is open to varying interpretations, bias, corruption etc.

Following JQ's point that rules "can be deemed legal or illegal by the sanctioning body at any time" is fraught with problems. How is anyone going to know what is going on, whether it be the officials or the competitor. I consider that if this would constitute a bad rule book.

Willy, that pic is of a set of rubberies of a TM KZ10B cylinder, these being mounted on a 54 mandrel to show their correct relationship. In this case, a B passage has been removed and a rough model of a direct air inlet (throttled) put in its place. I posted this here a round 3 - 4 months ago, just to show the principle. Following that, we applied this to the side of a kart engine, mainly to see if it would start. It sort of did, with this being the only inlet, all the rest being blocked off, isolating the crankcase from any airflow or scavenging function. As to its high speed operation, I haven't done anything since. Work and karting events just seem to get in the way. Notwithstanding, there is a very productive man on the case.

[2005bully]

posted by ken seeber
Irrespective, I am starting to think that the Ryger system is a form of direct air inlet system, and just used the below piston volume for starting and possibly some small contribution to the dampening of the piston downward piston inertia forces. The routing of the passages etc being necessary to route all the ingested air to pass thru the obligatory 30 carb.

Ken... From the information available that is the most logical conclusion. As an added twist..... Frits has said SIMPLE and a stepped piston just does not seem simple enough. What if instead of a stepped piston the separate primary compression chamber was fed by combustion pressure .... i.e. "exhaust". The chamber would inter mix or maybe even replace the first mixture exiting the transfer ports with hi pressure ex gases. This separate primary compression chamber would be fed combustion pressure from the previous stroke through a reed valve, thus making the pressure available to be released dependent upon the strength of the previous power stroke, as each previous power stroke becomes stronger the chambers exiting velocity would increase and exert more draw on the direct air inlet transfer ports. Kinda like a jet engine.... as speed increases it would deliver an ever escalating quantity of inducted air. That would explain the achievement of extreme rpm's. Perhaps this scheme would help promote hcci as well as lower the emissions by reducing the fresh mixture exiting out the exhaust. Where the theory falls flat is that there still needs to be some method of mechanical primary pumping action to get it started. Then again maybe stepped pistons are SIMPLE ??? Kermit Buller

[Grumph]

posted by ken seeber
Irrespective, I am starting to think that the Ryger system is a form of direct air inlet system, and just used the below piston volume for starting and possibly some small contribution to the dampening of the piston downward piston inertia forces. The routing of the passages etc being necessary to route all the ingested air to pass thru the obligatory 30 carb.

Ken... From the information available that is the most logical conclusion. As an added twist..... Frits has said SIMPLE and a stepped piston just does not seem simple enough. What if instead of a stepped piston the separate primary compression chamber was fed by combustion pressure .... i.e. "exhaust". The chamber would inter mix or maybe even replace the first mixture exiting the transfer ports with hi pressure ex gases. This separate primary compression chamber would be fed combustion pressure from the previous stroke through a reed valve, thus making the pressure available to be released dependent upon the strength of the previous power stroke, as each previous power stroke becomes stronger the chambers exiting velocity would increase and exert more draw on the direct air inlet transfer ports. Kinda like a jet engine.... as speed increases it would deliver an ever escalating quantity of inducted air. That would explain the achievement of extreme rpm's. Perhaps this scheme would help promote hcci as well as lower the emissions by reducing the fresh mixture exiting out the exhaust. Where the theory falls flat is that there still needs to be some method of mechanical primary pumping action to get it started. Then again maybe stepped pistons are SIMPLE ??? Kermit Buller

If that mystery lump on the barrel is some kind of pressure bleed port from the exhaust, and looking at what you've both posted, could we be looking at some form of pressure wave compressor ? Comprex comes to mind as an example vaguely similar in function. IMO, very little primary compression is needed at cranking speed to fire things up, just get a little vapour in there...
But of course, I'd think a form of pressure wave compression would fall down on the no supercharging clause.