i keep thinking that somehow the unburnt mixture is prevented from escaping the cylinder. how else could a 2t have such good emissions and still look like a traditional engine ?
Hardcore Biker
i keep thinking that somehow the unburnt mixture is prevented from escaping the cylinder. how else could a 2t have such good emissions and still look like a traditional engine ?
L-Plate Rider
Looks very interesting. I am following the same process although a few steps behind you. I'm curious if the 3D printed PLA must be "finished" in some way to smooth the layers or is that taken care of after casting (by machining in some way)? I don't yet have privileges to send PMs on this forum but please keep me updated on the build and show share some pictures when you finish machining the cylinder.Originally Posted by Peiter
i'm a wanker
what did you call guys that dont blipp the throttle lol(-: good race , just picked up a nsr engine my self , did i do the right thing now lol
No8 Wire Extraordinaire
Pesky little blighter isn't he, but Taupo is a bit of a goat track and it seems like he can track real well out of the shortcut where there's a fair bump on the exit, and crucially onto the front straight.
Fair blasts past people at the start. Does it stay in a reasonable heat range throughout?
Don't you look at my accountant.
He's the only one I've got.
Low personal B.M.E.P.
Well historically it's always been an external pump...
The long piston with a ring or rings on the bottom sealing the crankcase off has been done many times before - and is still being done on big 2 stroke diesels.
This enables the use of full pressure lubrication.
I still come back to what I pointed out a long ways back, it would seem that it's only what's in the transfers that gets to the combustion chamber on any given power stroke. And that is drawn there by pressure differential...Which in a conventional layout also recharges the primary space - crankcase and transfers.
If Harry ( he seems like an old friend now...) has found a way of refilling the primary space that we haven't thought of, I'm looking forward to seeing it.
Anorak
One way would be by purge scavenging as a Detroit diesel does with fresh air rather than unburnt mixture, another would be by excluding oil from the mixture burnt.
but a one diameter piston. it would entail a internal piston shaped dye sealed off at bdc otherwise the mixture would remain stagnant there.
Kinky is using a feather. Perverted is using the whole chicken
Low personal B.M.E.P.
If as i suspect, it's only breathing through the transfers, there's no mixture going under the piston at all.
I'd point out that the homologation papers say one exhaust port....If it's only refilling the transfer duct volume, it wouldn't need the very big depression that is used to refill the crankcase volume, so one port should suffice. It could be a lower timing too, which would help emissions.
Pretengineer
Do blip, just cant hear it on the 2T, but I've got no excuse for the ugly over-rev going into 2nd gear
Glad to hear you've joined the dark side. Most fun bike ive ever ridden the NSR. If you want to know anything that we've done just ask, I can give you all the files for the billet heads and head inserts that I'm running if you're keen.
Got a good radiator now, sitting anywhere from 55-60 depending. Still haven't done any ducting though so it's not being very efficient with it's air flow. Good to know I have extra cooling up my sleeve for when we get into summer.
Pristine Knee Sliders
What about FIK? Illegal there too?
Forum whore
You are right if we just compare the maximum torque values. But at 17500 rpm the Ryger's torque is quite a bit higher than the torque of your regular top level 125 at 17500 rpm, let alone at 30000 rpm...
In a reed valve engine this time is limited by the exhaust timing, which is conventional in the Ryger. But you may want to rethink the bold part of your statement..The only thing creating a big suction is the exhaust so the exhaust must be "seeing" the carb better or for more time (or both), than in a regular engine.
True, but there is more to it. The Ryger engine makes us face the fact that conventional combustion is anything but perfect. Trapping all the fuel in the cylinder is one part of the equation; getting it all to burn completely is part two.In order to have good emissions and economy, the scavenging must be such that any and all air/fuel getting into the exhaust port gets shoved back into the cylinder
Let's talk conventional engines for a moment so you may better understand Jonny (just returning your egg).
As long as there is a difference between the maximum volume and the minimum volume of the crankcase, it's a pump. But it's a mediocre pump; it can hardly generate any pressure.
The maximum closed volume is when the inlet shuts and the minimum closed volume is when the transfers open.
For an Aprilia RSA (not the worst of conventional engines) the inlet closes at 85° after TDC = 28 mm below TDC = 64,1 cc below TDC, and the transfers open at 114° after TDC = 40,9 mm below TDC = 93,8 cc below TDC.
Total crankcase volume at TDC is 675 cc, so the primary compression ratio is (675 - 64,1) / (675 - 93,8) = 1,05. Is that mediocre or what?
Nevertheless it is a compression ratio; what else would you call it? And you need something like it to start an engine if you don't want to violate KISS.
PS: will you guys please slow down a bit? your posts are too good to ignore, but answering them reallly eats into my day.
PS2: if he wasn't taller than me, I'd say that Flettner is a clever little bastard. And he's not the only one here....
Hardcore Biker
Fletto,
We checked our R&D archives and, yes, what you say is correct. The RAG engine certainly did start (the main aim of the test) and run. Not spectacularly marvelous, but it did run under no load at up to 3 to 4k. Didn’t try any more as it kept trying to vibrate itself across the floor.
It didn’t run well, if at all, when it was direct piston ported. We then made up a small single petal reed block (3D printed), requiring an extended manifold. Then the action. Note that this was achieved with a small groove, which could have been emulated with an equivalent passage. Not too sure if this a transfer duct or is it an exhaust passage?
Wet sump 2 strokes. At Orbital, we did both a 3 cyl 1 litre and 6 cyl 2 litre versions. These were wet sumped and used a Roots style blower for air flow. To maintain compactness, the transfer passages were shared with the adjacent cylinder ie one vertical passage splitting to go either way to whichever port was open. Probably not good for airflow (Wobbly would probably squirm if the saw them), but enough for the power curve of the time. The 6 cyl was actually installed and run in a BMW car (which incidentally had the most erotic exhaust note ever). The prime purpose was to try to reduce the NVH aspects of a “roller bearinged” crank scavenged engine and used plain bearings for the crank and rods. All seemed to work, with a considerable NVH improvement, and that oil control was good, with no exh smoke, smell or excessive consumption.
The pistons were full skirted with an oil scraper at the bottom, placed such that it would never uncover a port when at TDC. Unfortunately I don’t have a pic or sample, but do have for another 2 stroke DI externally scavenged engine project we did for a UK company. Same in overall principle, but in this case was of 86 bore and used a “shrunk in rod pin”, hence the relatively large pin diameter. I know it’s shitty looking, but hey.
Given all this, here is a pic of what Harry’s piston MIGHT look like, given that it MIGHT be full skirted, meaning it is a simple one piece design with no passages, necking, volumes etc in the piston itself. It was based on the fact that the piston pin boss didn’t protrude beyond the oil scraper groove, meaning that the direct side thrust axis was within the length of the piston and not overhung.
Jeez, we could make these OR could we? It all comes down to the patent status and tactics, which is all a bit of an unknown to virtually all of us. The main feature of patents is that no-one can “make – use – sell” a patented technology unless they are the patent holder or one who has been given permission to use it, eg a licencee. Lodgernz might be able to comment further
So if Smitty,TZ350 and co made one, even for their own use, it could be deemed to be in breach and Harry could take you to court and try to claim damages. Damages bring primarily loss of income to Harry (in this case zero). So, would Harry do this, would Harry bother? Absolutely not. He’ll be happy enough to start initially making the KZ engines to show the world how much better they were and then license the technology to volume engine manufacturers. Let all the rest utilize and demonstrate the technology, known throughout the world as Ryger technology (look at Elon Musk of Tesla fame, he essentially allows anyone to use many of their patents for free). Fame and $s for Harry, not too bad at all.
3 months to go.
"Success is the ability to go from one failure to another with no loss of enthusiasm.”
Hardcore Biker
Peter, what you have done with the PLA investment casting is great. Would it be too much to ask if you could give more details on the technique, I am sure many have lots of questions?Hi guys,
The cylinder has been drawn in a CAD program and 3D printed in PLA after which it was cast in aluminum by using investment casting. At this moment I am machining the raw cast piece and making an adapter plate / head inserts, etc.
For now I think this is enough before my post becomes confusing. In the attachments I have posted a picture of the bike, the cylinder, its mold and the cylinder during the investment casting process and the power curve
cheers,
Peter
However, before you might do this, maybe Hooser could somehow transfer this to the Foundry section rather than keeping it under ESE.
Huser, have you gone to bed yet?
"Success is the ability to go from one failure to another with no loss of enthusiasm.”
Hardcore Biker
Ah yes, a stepped piston, the largest diameter of it would probably be considered the bore size.
Highway Biker
Thinking out loud some more.
If the crankcase volume is small, perhaps approaching just piston displacement, then the crankcase pump would suck in A/F much like the action of filling the cylinder on a 4 stroke intake stroke, but with ports that are big and open fast the displacement would fill quicker than the same displacement could be filled on a 4 stroke with valves, so the little crankcase should be able to be filled to a very high rpm, like 30000. Basically pumping 125+cc every time around.
With a very small crankcase the pressure in the crankcase would be getting pretty darn high as the piston approaches BDC because it would be akin to what's in the cylinder when the piston approaches TDC, so the flow from the crankcase to the cylinder could be very brief and very intense. The exhaust blowdown would be not critical because there would be lots of time between exhaust opening and crankcase discharge and the crankcase discharge pressure would be very high. The very high discharge pressure would also give spectacular A/F mixing.
Now if the exhaust timing were somehow asymetrical then the exhaust could be closed real early perhaps at BDC keeping any A/F from escaping and leaving some exhaust in the cylinder to activate the next combustion cycle.
The exhaust pipe would be less important than usual but would at some speeds help blowdown.
Probably a fatal flaw or two here and I haven't spent any time figuring out how to achieve it mechanically. Just some off the cuff thoughts for now.
Edit: One fatal flaw that comes to mind is that significant crankcase pressure would cause significant power losses due to compression pumping.
Forum whore
Start your own thread and fill it with anything posts until your post count gets high enough.
Someone else might be able to tell you what that post number is.
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