Three rotary discs fed by three Amal carbs?
Hardcore Biker
Three rotary discs fed by three Amal carbs?
Hardcore Biker
Hardcore Biker
Looking through the zip file of MZ pictures, it seemed they were experimenting with crank-case water cooling back then. Vic Willoughby describes Helmut Fath using a watering can on Phil Read's Yamaha engine running on the dyno, but, I guess, that would be later.
Hardcore Biker
If KTM's next big thing is anything like you just said, then we know what's going on hereOriginally Posted by Flettner
I think they will be using what I call DTPI, 'delayed transfer port injection' , as I have done on the YZ. This approach allows for the fuel to be delivered at such a time as to NOT escape out the exhaust. It would take a LOT of time to fully map an engine to get best results and some flash equipment but the upshot is nearly as good as DFI. This approach lends to cheap and durable hardware and allows for better fuel air mixing than DFI (I guess certainly in terms of cost)
We didn't have flash equipment for the YZ, just fuel burn results and seat of the pants (and a home made oscilloscope of sorts) but to show how easily it can be done we were getting between 14% and 21% fuel savings (compared to an identical YZ with a carb), same top end power!
So I would say DTPI is certainly not to be disregarded as a useful technology.
Now all they need is a sliding cylinder and HCCI and no oil burn at all! AND a chamber wave modifier, could be called an exhaust throttle.
Of course, DTPI definitely is a useful technology. Do you know how much of your fuel savings came from better AFR control and how much was due to increased trapping efficiency? Are you injecting against the transfer flow direction, too? Seems kind of counter productive in regards of increasing trapping efficiency (but is ideal for mixing).
Generally, I think for two-strokes to have a comeback in anything else than a niche market, they need to be just as clean as four stroke engines regarding engine raw emissions.
Compared to four-strokes, two-strokes are typically:
- lower on NOx emissions (lower peak temperatures if you fire twice as often)
- much worse in HC, which is due to the scavenging losses (see below)
- worse in CO2 emissions, which is basically fuel consumption, or BSFC (grams of fuel per kW per hour)
- better or worse in particulate emissions (better with PFI, might become worse with high pressure direct injection, longer mixing time is better)
- and CO values depend on AFR setting
(Both types of engines burn oil, but it has already been shown that this can be dealt with, regarding the two-stroke, once the other problems have ben solved.)
So, scavenging losses and BSFC need to be improved. Luckily, if you reduce scavenging losses you also reduce fuel consumption.
Okay then, so the E-TEC is exactly what we are looking for? Well, not quite. The E-TEC has a DI system capable of about 35bar pressure from what I read. This is not enough to get the required mixture in the cylinder and mix it between exhaust port closure and start of ignition (~70 ish deg CA). So at higher loads, it has to inject for much longer periods of time thus generating scavenging losses just as a carbureted two-stroke. How can this be solved? Simple, more pressure. How much? Much more. How much exactly? Well, today's latest car technology uses an injection pressure of about 250 bar in their gasoline engines. These are turbocharged around roughly 20 bar (4-stroke) BMEP, which would be equivalent to 10 bar two-stroke BMEP. And they turn about 6500 rpm. That's 3250 injections per minute, let's say 1/3 of what we would need (~10k). So we're at 750 bar now, right? As we would only need half of the mixture per injection (assuming one injection per stroke), we can halve that and arrive at 375 bar and we realise that we have only about 70 deg CA to get everything done, whereas the 4stroke has more than 180°, (but uses the time available for more than one injection most of the time).
All in all, I think as soon as gasoline DI injection technology has reached a level of 500 bar in serial application (500 bar is what F1 is currently running), and CFD computing power is available abundantly, too, one could give it a try. On the other hand, adapting today's car technology one could already get a quite clean two-stroke, only that it's "clean" area of the engine map woud be somewhat revs and power limited.
Forum whore
You know, the irony, one of my first home made engines, a uniflow, with two pistons in one cylinder controlled the hydrocarbon loss easily just by architecture. More complicated engine but simple fuel control, just with carburetor. Perhaps I should revisit this engine. The apparent down side of this kind of engine is poor transfer delivery, I think with careful transfer layout / aiming this problem can be largely mitigated. The last version of this uniflow engine had an air buffer between the fuel air and the exhaust gases. Cooling the exhaust piston was supposedly going to be my main issue (experts said) but in fact was not a problem with the eventual layout, being all the fuel was delivered through under the exhaust piston. Maximum piston cooling. I guess another one of the problems with the uniflow was combustion chamber shape but with HCCI or perhaps I should differentiate my system by calling it just CCI, Controlled Compression Ignition, this combustion chamber shape might not be such a problem?If KTM's next big thing is anything like you just said, then we know what's going on here
Of course, DTPI definitely is a useful technology. Do you know how much of your fuel savings came from better AFR control and how much was due to increased trapping efficiency? Are you injecting against the transfer flow direction, too? Seems kind of counter productive in regards of increasing trapping efficiency (but is ideal for mixing).
Generally, I think for two-strokes to have a comeback in anything else than a niche market, they need to be just as clean as four stroke engines regarding engine raw emissions.
Compared to four-strokes, two-strokes are typically:
- lower on NOx emissions (lower peak temperatures if you fire twice as often)
- much worse in HC, which is due to the scavenging losses (see below)
- worse in CO2 emissions, which is basically fuel consumption, or BSFC (grams of fuel per kW per hour)
- better or worse in particulate emissions (better with PFI, might become worse with high pressure direct injection, longer mixing time is better)
- and CO values depend on AFR setting
(Both types of engines burn oil, but it has already been shown that this can be dealt with, regarding the two-stroke, once the other problems have ben solved.)
So, scavenging losses and BSFC need to be improved. Luckily, if you reduce scavenging losses you also reduce fuel consumption.
Okay then, so the E-TEC is exactly what we are looking for? Well, not quite. The E-TEC has a DI system capable of about 35bar pressure from what I read. This is not enough to get the required mixture in the cylinder and mix it between exhaust port closure and start of ignition (~70 ish deg CA). So at higher loads, it has to inject for much longer periods of time thus generating scavenging losses just as a carbureted two-stroke. How can this be solved? Simple, more pressure. How much? Much more. How much exactly? Well, today's latest car technology uses an injection pressure of about 250 bar in their gasoline engines. These are turbocharged around roughly 20 bar (4-stroke) BMEP, which would be equivalent to 10 bar two-stroke BMEP. And they turn about 6500 rpm. That's 3250 injections per minute, let's say 1/3 of what we would need (~10k). So we're at 750 bar now, right? As we would only need half of the mixture per injection (assuming one injection per stroke), we can halve that and arrive at 375 bar and we realise that we have only about 70 deg CA to get everything done, whereas the 4stroke has more than 180°, (but uses the time available for more than one injection most of the time).
All in all, I think as soon as gasoline DI injection technology has reached a level of 500 bar in serial application (500 bar is what F1 is currently running), and CFD computing power is available abundantly, too, one could give it a try. On the other hand, adapting today's car technology one could already get a quite clean two-stroke, only that it's "clean" area of the engine map woud be somewhat revs and power limited.
katinas, whats happening with your Ryger test engine?
Weekend cruiser
100% correct !
Low personal B.M.E.P.
Well if we're assured it's three rotary discs, are they inside the crankcase chambers ? Looking at the angled inlets, If the discs are inside - with one crankweb cut away - and the inlet ports come into each crank chamber at an angle, that would explain the layout.
I've seen a similar internal disc in one of Irvings books - used in a cyclemotor of about 30cc.
Hardcore Biker
Less value than pure aluminiumscrap also as it is contaminated with nicasil
Anorak
https://www.kiwibiker.co.nz/forums/s...-tuner/page721
plus some more MZ
https://www.kiwibiker.co.nz/forums/s...post1130887057
https://www.kiwibiker.co.nz/forums/s...post1130411899
https://www.kiwibiker.co.nz/forums/s...post1130410698
https://www.kiwibiker.co.nz/forums/s...post1130150906
Kinky is using a feather. Perverted is using the whole chicken
Anorak
Kinky is using a feather. Perverted is using the whole chicken
Hardcore Biker
Thanks for that. I have actually been around a few racing MZs including a 125 which had a Rotax barrel fitted...
Forum whore
Then this chaos might look familiar.
Forum whore
Well it appears that me who has no life, and is an angry little man + SwePatrick + jamathi ( Jan ) + koenich, have scuppered the whole Ryger reveal.
We simply have not been nice enough and licked Luc's bum sufficiently for him to tell us anything.
He has visited her twice recently and gone away saying nothing.
Maybe the big race where nothing occurred , when winning was supposed to happen, with 66Hp was too much of an embarrassment to continue the charade here any longer.
Really would have been great to have the " Exclusive World First Ryger Reveal of Hard Fact " from Luc on here - but no, we are not good enough, just yet.
So lets all try " not mentioning the war " at all, and maybe he will come back.
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
Hardcore Biker
You might be right there.
The bung may have fallen out of his engine on this occasion...
Hardcore Biker
Well, the one I looked at was all in one piece! It was only because I poked my head almost inside the fairing that I noticed the Rotax barrel but it made me wonder if there was some connection between the two companies.Then this chaos might look familiar
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