Two Stroke Motocross
Two Stroke Motocross Forum => General Two Stroke Talk => Topic started by: 2smoker on May 06, 2010, 09:29:13 PM
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Omnivore Interview (http://www.youtube.com/watch?v=-vl9MYsHdRw#)
ยป Home Lotus Engineering (http://www.youtube.com/watch?v=zaDL-B0cKQw&feature=related#ws)
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After making a bunch of cars with uninspiring Toyota engines, Lotus has done something absolutely epic. I like their little robot in the exhaust, too, just because it's bizarre.
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What about starting the engine without a spark? just by turning the compression ratio up.. sick! compression ratio from 10:1 to 40:1 lol Can run on Diesel to Ethanol lol DIrect Injection & Wet sump
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Well, running without spark isn't necessarily a new thing. Honda's super-cool whiz-bang two-stroke could do that, although of course it wasn't omnivorous. They could've made some real ground with that, but of course I think we know what happened to that "dangerous" little bike. Can't let anything like that threaten the camshaft mafia.
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Very nice.
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Your right JETZcorp!Hondo would never let that happen!God forbid the hondoo corp.lose any money!That engine would have changed the status quo for hondoo and they would have lost money in the short term but if the powers that be at the Hondoo corp.did'nt think "bass ackwards"they would probably be sitting pretty or prettier by now.
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Very true maicoman.
I find it bafling a company can be so against a product that their own engineers have proven can be better then the status quo.
They have proven the 2 stroke works but god forbid if anyone else agrees.
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What I really don't get is why they do things like they do. I mean, everybody is quick to say they're going four-stroke for profit, but surely their slick-haired businessmen and accountants would've seen that sucking that extra profit margin out of their customers couldn't be sustainable. And besides, if they'd gone ahead with that thing, maybe dropped a couple of patents, they could have market share and be reaping profits that would make Rockefeller piss his pants. Strange company.
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I heard something interesting about Honda. I was told that apparently they tried several of those two strokes that can work without a spark in the Dakar. Is that true? If so, than the engine must have been very well developed and probably close to being finished. What a loss :(.
Anyways, very interesting technology, amazing... and based on a two stroke as well... Perfect :D.
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i have a better idea... an engine that is neither 2 or 4 stoke, has no cylinders is 1.3 litres in capacity and is capable of 6 second 1/4 mile passes ;)
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Sounds like your talking about a rotary engine Rota
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That's what it sounds like to me, too. Too bad they get bad gas mileage, though.
DangisMX - Here's some info on the spark-less two-stroke thing from Honda.
"et's look now at what Honda was doing just before they announced to the world, "No more two-strokes!" The story really begins a long time ago when people discovered that two-stroke engines would sometimes run without spark-ignition. That is, one could pull off the sparkplug lead, while the engine was running, and it would continue to run as if nothing had changed. People said, "It's dieseling." Actually, what was happening was very different from combustion in a diesel engine. The phenomenon was best explored by Shigeru Onishi in the 1970s. He called it "Active Thermo-Atmosphere Combustion (ATAC)." He said, "With ATAC the fuel consumption and exhaust emissions of two-stroke cycle, spark-ignition engines are remarkably improved, and noise and vibration are reduced." He eventually showed that a carbureted two-stroke engine could be more efficient (lower fuel consumption) than a diesel engine. But only within a narrow range of speed-load conditions.
In the 1990s, Honda R&D Chief Engineer, Yoichi Ishibashi, wanted to clean up two-stroke motorcycle engines. He called ATAC: "Activated Radical (AR) Combustion." Onishi's engines ran generators at nearly a constant speed. Ishibashi needed to greatly extend the range where AR combustion was stable. He found that throttling the exhaust was the secret. He developed a 400-cc single-cylinder engine. For real-world testing, several of these EXP-2 engines were put in endurance-racing chassis. They ran in the Granada-Dakar Rally and the Baja 1000. The results were good enough for Ishibashi to press on and develop the engine further.
Two bikes were entered in the Dakar - both finished. As Ely Kumli reported in 1997: "The race results were very good even though the bike was not designed to win races, but to test new technology. When the dust settled, the EXP-2 had earned 5th overall and first in both the under-500cc and experimental classes..."
As it turned out, the second-string riders had been given the better equipment! "Compared to Honda's NXR780 four-stroke twin rally race bike," said Kumli, "the EXP-2 has very similar performance, with several advantages. While the single-cylinder EXP-2 produces 54hp to the big NXR's 71hp, they both make 58 lbs-ft of torque, but the EXP-2 is 118 pounds lighter giving it a slightly better power-to-weight ratio. What all this boils down to is that the EXP-2 has about the same real-world performance as the 780, but with substantially better fuel economy and lower emissions."
As good as that sounds, Ishibashi was just beginning. The exhaust valve prevented most of the fresh charge (fuel-air mixture) from getting lost out the exhaust port, but he needed to scavenge the cylinder with air only, and admit the fuel late in the cycle. He came up with a 'pneumatic injection system' that used a standard four-stroke-type fuel injector. Ishibashi summarized the results: "...PDI-AR Combustion drastically decreases HC emission close to the level of four-stroke, and CO and NOx level is 1/5 and 1/7 of four-stroke level respectively. Furthermore, fuel consumption is improved 15% compared with the four-stroke." His English isn't perfect.
I will add: A Honda four-stroke engine giving equal performance had carbon monoxide emissions 500% higher and oxides of nitrogen emissions 700% higher than his two-stroke. Without an oxidizing catalyst, the two-stroke hydrocarbon emissions were slightly more than the four-stroke's, but with a cat, the levels of HC were the same. The CO levels dropped, but the two-strokes advantage over the four-stroke was actually greater. (NOx is unaffected by an oxidizing catalyst).
Obviously, Honda had a good engineer doing good work. He had one more song to sing before the bean-counters dropped the axe on him...
He did not begin with the long-stroke CR250, but with half of Honda's NSR500V. This was a case-reed road-racing engine with a square bore-stroke ratio - like the McGrath generation YZ250s. Honda said that it made "135-plus horsepower" at 10,500 rpm; about 68-hp for a 250.
If ten-five makes it sound like all the power was on the top end, one rider called it a "torque monster" and said the power was "similar to an open-class motocrosser". This engine was introduced at the first 500 GP, 1996. I have given these details because there has been, at least, the suggestion that the long-stroke 250 two-stroke had reached some sort of a technological limit (at less than 50-hp) and that the 450 four-stroke was some sort of a 'solution' to this 'problem'. In 2005, MotoVerde magazine (Spain) dyno tested the CRF450 and the RMZ450 and got 56-hp and 55.2-hp, respectively.
So this was the basis of Ishibashis new 'environmental conscious power unit'. But he really only used the parameters; he built a new design. He got AR Combustion to work from about 3000 rpm to peak power - meaning that the engine could operate normally within that range without an ignition system! At the very bottom, the sparkplug initiated combustion and his Pneumatic Direct Injection limited HC and CO emissions. The engine made 60-hp at 11,000 rpm.
Because the solenoid injector fed an anti-chamber - not the cylinder - its high-frequency limit did not restrict high-end power. In other words, Ishibashis approach did not require the invention of any new technology, only basic engineering. The technology required existed in the 1970s.
There was a rumor that the NSR500V might be turned into a killer street bike. Of course, that never happened. Instead, Ishibashi was sent off to design Civic door latches, or whatever...
About now, someone should be asking: "If Honda knew how to make two-strokes that are cleaner and more economical than their four-strokes, that do not require any new technology, and that could win endurance races, why didn't they produce them?"
Back in 1984, Steve Anderson (then Technical Editor of Cycle World Magazine) went to Japan for a VIP tour of Honda's (then) new racing R&D facility. There, Takeo Fukui, Design Director, "...made it clear that Honda views itself as a four-stroke company that will not be satisfied until it wins all of its championships with four-strokes." Simply put, the four-stroke engine has been company policy; in fact, it has been more of a religion. Anderson saw, "...shelf after shelf of oval pistons..." and was told that engines were running "...with at least eight valves per cylinder..." and turbo charging. We haven't heard anything about oval pistons in a long time because, after spending umpteen millions of dollars, somebody saw that it was a really stupid idea. It was a way of getting around the racing rules. Four-strokes couldn't win within the rules, so Honda had to find some way to beat the two-strokes and/or the rules. The trouble was, no matter what the shape of the pistons, or how many valves they could stuff in, or how many rpm they could get out of them, the two-strokes kept getting faster and the four-strokes weren't even able to keep pace. In 1995, Mick Doohan was asked how much power his NSR500 two-stroke made: "I can't tell you that, but I can tell you that if Honda produced a one-liter motor it would make upwards of 400 horsepower."
It was about that time, it seems, when one of the four-stroke monks had an epiphany: "Instead of spending more money on exotic engines," he might have said, "which hasn't been getting us anywhere, why don't we just buy the AMA and FIM and make our own rules? For instance, we could require that all two-stroke riders wear their helmets backward - if they can't find the first turn, we have to win!" And that is - sort of - what happened.
http://www.dirt-bike-tips-and-pics.com/future-of-two-strokes.html (http://www.dirt-bike-tips-and-pics.com/future-of-two-strokes.html)
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It's strange that most people blame Honda for the damage the sport has suffered due to overstressed 4s's taking over when it was Yamaha that first brought out the YZ400F and then the 250F. Honda was actually kind of late getting into the 4s game as a result of (I think) having just redesigned the CR250 2s. I place most of the blame at the feet of sanctioning groups such as the FIM and the AMA. What happened next was the major manufacturers exploiting the situation to gain market share and "line their wallets".
It should be noted that BRP and Bombardier Corp. are now seperate business entities and I'm not sure what in the way of resources is shared between the companies.
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As far as manufacturers go, I do think Honda was the worst. I mean, Yamaha started the four-stroke thing, but considering that they're the only Japanese factory that continues to tow the line on two-strokes, you have to start thinking that they might just actually like to have a diverse product line-up and explore new ideas. Then again, I think I remember reading that Yamaha (along with Suzuki) was pushing harder than the rest to get the 500s kicked out, which is pretty low. I think they all played a role in the death of two-strokes in motocross, but with on the picture as a whole, I think Honda was the worst. No one else, as far as I know, has completely taken two-strokes off their line-up, including minibikes and yard equipment. And I really don't think any of the rest stood on the verge of revolutionizing the entire world of car and motorcycle engines, as Honda did, but scrapped it anyway. That's why I put my hammer down on Honda more than the others.
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yeh honda don't even make a 2 stroke outboard, i think the little 85's should never be replaced!!! , actually i'm saving up for a big wheel 85 for my girlfriend at the moment, went to honda the other day lookin at 85's and the guy was tryin to talk me into a 150, haha i actually had fun pointing out that i don't want an unreliable 4 stoke
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I think storm clouds "are a brewing" in the great 2s vs. 4s debate. You see ,I read an article recently about how a clean sheet design BMW demolished the competition in a 1000cc sportbike shootout. The combination of state of the art chassis and engine management electronics gave the bavarian machine a decisive advantage, the 180 hp (!) engine had a 20hp advantage over the nearest japanese rival.
That 1000cc BMW engine and a bandsaw would give us a 45+hp, reliable, 250cc 4s MX'r. All of a sudden BMW's aquisition of Husqvarna makes sense. I think it is safe to say the Germans are coming.
Where does that leave the 2s? First of all I think if you are still holding your breath waiting for the japanese or KTM to bring out something new you will have turned blue and fallen over by now.
Companies,no matter how massive, are defined by finite resources and all of their R&D dollars will be going into further 4s development.
Mid level companies like Gas Gas (that produce their own engines) are in a bad situation , any move they make will require resources virtually beyond what they can handle. The solution (I think) lies in the "cottage" industry - where inovation usually takes hold.
In the late 60's and early 70's Fichtel and Sachs high volume manufactured, think "Economy of Scale", 50/80/100 and 125cc 2s engines that were tough and torquey. These engines gave rise to a virtual explosion of cottage manufacturers around the globe, from Allouette in Canada and Rupp in the U.S., Monark in Sweden, Dalesmen and Tyran in the U.K., KTM in Austria, to a "Kazillion" Italion manufacturers such as Ancillotti and SWM. German Sachs powered DKWs beat bikes 3 times their size in the Californian desert.
I think the 2s revival solution may lie right here in Canada. All BRP has to do is , thru. their Austrian subsidiary Rotax, is cast up a set of cases to hold the bits and pieces of what they already produce:clutches/transmissions and powerful,state of the art, emissions freindly Skidoo powerheads.Cases that would allow cottage manufacturers to produce competitive 250/400cc 2s MX's and enduros. Think CCM or even a reborn EMC. I am certain the demand is there to allow an economy of scale that could make it all happen. If BRP would get to work, I think the "little guys" would shake up the sport.
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Thanks for the info JETZcorp. Really interesting stuff. What a shame though :(. Maybe someone will pick up this idea and try to do something with it again...
Yamaha might have started the whole four stroke thing, but they still make their YZ bikes. I want one! Yamaha all the way! (My next bike is definitely going to be the YZ :) )
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Just out of curiosity, is there a particular reason for wanting the YZ in particular? I don't mean to say the YZ is a bad bike, but I just wonder sometimes if people automatically go Japanese, figuring the big company is going to give them the best bike. I've heard big things about TM's line-up, and KTM seems to be making good bikes, and I wonder if there's anything in particular that put you toward the YZ, like looks or price or whatever.
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In Lithuania (where I live) we don't yet have any dealers for TM, Maico, Sherco and all the small companies. Maybe we never will have, it's a small country, small market, not very profitable. I don't fancy on trips to Latvia (neighboring country) to pick up parts. Of course I could order from Ebay or from the shops abroad, but why bother, Yamahas are decent bikes I think, and theres a dealership near by. KX and RM bikes are kind of being manufactured, but not updated at all, so I thought KTM or Yamaha is the best choice that I have. I already had a 150 sx and was very disappointed by the costumer service here as well as part prices! The bike was nice, I liked it, but it broke down far too often. A couple of people told me that they had Yamaha YZs before they switched to 4t bikes, and that they were really reliable. I'm not aiming to be a national champion or anything, so really I care very much about reliability and running costs and not so much about performance, a novice or an intermediate rider couldn't really feel a big difference between a KTM or a Yamaha or any other similar two stroke I think. Even If I could, I wouldn't know how to use it to my advantage yet :D.
To sum it up, I plan to buy a Yamaha because it's the most acceptable choice for me at the moment. Besides, I think they're kinda cool anyways :D.
P.S. If I could, I think I would go Maico !!!
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Okay, that makes a lot of sense. And from what I've heard, customer service with KTM isn't only a problem in Lithuania. ;)
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I totally agree with you JETZcorp about Hondoo!I have in the past placed a large amount of blame on Yamaha for bringing the YZ-400 4 choke out when they did and I still beleive that certainetly did'nt help the 2-stroke situation however I also hate Hondoo for not using that technology when they most definetly should have!As far as Yamaha goes like I've said in a previous post their only saving grace is the fact that they have kept the 125 & 250 2-strokes in their line up but unlike KTM their not making to many if any at all improvements on their 2 stroke line up.So for me the bottom line is I'll stick with my KTM's & only buy the European brands that still beleive in 2-stroke technology.And so far at least for me I have'nt had any problems getting parts for my 2008 KTM but I'm seriously considering buying a 2010 KTM-300xc and from what I've been told & heard from the local shops is that the new KTM's are getting harder to find!
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DangiMX: Buy the YZ. If thats the only dealer in your area stick with what you know and you can get parts for.
The Yz engine is well known for having a very usable power band.
Sachs: BRP owns Rotax/Skidoo/Seadoo/Evinrude/Canam.
Bombardier still makes Trains & Lear Jets.
There is a fair bit of intercompany shareing on products within BRP.
Earlier on Rotax sent engineers over to Evinrude to learn about the DI engines.
You are dead right about the motors being able to be sold to the cottage industry.
To fit the DI system in another product is quite simple from an engineering point of view.
I have quite often thought it would be great to fit a etec injector on my TM.
First i would need to machine up a new cylinder head to fit the injector and move the spark plug of to one side.
Next, modify the carb into a throttle slide and fit a TPS.
Remove the crankshaft and drill passages from mains to big end.
Fit oil feed holes through cases to the crank mains.
Then fit a potentiometer to the power valve shaft to measure power valve position.
Next fit a more powerfull stator to supply the power needed to run the system.
Next just bolt on all the sensors, oil/ fuel pump and you are ready to go !!!.
NOT.
Unfortunatly i am no computer programer.
Thats the problem.
It is actually pretty simple except for the programming.
I know i have simplified thing here but you get my point.
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After making a bunch of cars with uninspiring Toyota engines, Lotus has done something absolutely epic. I like their little robot in the exhaust, too, just because it's bizarre.
So you've become a powervalve affecianado eh jetzcorp?Whoda thunk it? ;D
As for the Yamaha thing.I've always been a euro fan but I've been disappointed by the suspension and niggling engineering details on my last three.No such concerns with the YZ.Besides,it's blue ;D
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Besides,it's blue
:D Exactly
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Hey Ford,what suspension & niggling engineering details have dissapointed you with your last three Euro brand bikes? ::) or were you talking about your last 3 pair of blue European panties riding your a$$ the wrong way or WHAT??? :-\