Two Stroke Motocross
Two Stroke Motocross Forum => Technical => Topic started by: Out of Order on January 10, 2010, 05:01:00 PM
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Ok, I have seen a million posts on Direct Injection, you decide in this poll.
The "Other" option is for any thing else, if you decide "Other" post what it is. I would like to see why you choose your pick, but is optional. For now.
Alright bring it on!!!!!!!!!!! ;D
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A "conventional" two stroke engine which we all know and love is fine with carb/carbs. Fuel injection, if done properly, may have certain benefits in some cases with the four bangers but we don't need to worry about that.
But as I said before, DI is not about getting fuel into the engine "per se", it is only a part of a completely different type of engine which I think has the ability to put the four stroke back in it's rightful place. And that place is NOT in lightweight competition motorcycles.
Everything I've read, seen, and heard leads me to believe that the long term future of two-stroke lies primarily with direct injection and for that reason I want it to prosper.
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There are reasons (some of which I know) why D.I. has not been released for production DIRT BIKES. If it was that great, it would be out there. KTM has been dancing around the issue for quite some time now. They would have the market right now. Yet and still, they are "working" on it.
It is worth mentioning again. If you can't tune A BIKE WITH A CARB (IMHO most can't) you won't be able to tune a bike with EFI. The concepts are exactly the same. You change electronic "jets" with your laptop rather than brass with tools. EFI has NOT fixed the 4T's inherent problems (I posted the quotes a awhile back) and DI, EFI won't help 2T's either. It's a perception, not a reality.
How many times do we hear a 4T is easier to ride (it's not, especially a 450, ask Villapoto) that 4T's with EFI are easier to tune, won't bog (ask Jeff Alessi about that), it hasn't. So, we are dealing with perceptions, not reality. I don't know how you get the ignorant masses to reality. That's not my job. That is what the AMA is for. You can see our immediate future, unless AMA is either broken or or replaced.
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All the above is promising. I picked other because I think the boyesen engine is really promising. I like the fact you can use a carb, FI, or DI with it. Also the exhaust valve will prevent most of the crankcase fuel/air mixture from escaping through the exhaust port. This is technology that should have been done years ago, but wasn't. To me this looks like an alternative to FI. I didn't say DI because with DI there is no fuel in the crankcase therefore the engine acts like an air pump. FI is just a glorified carb with electronics.
I hope Boyesen keeps on developing this engine, as it looks like a big contender to the big fat four pokes. :D
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I'm agnostic in this one, so I didn't vote. I defer the future to the free market.
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If you can't tune A BIKE WITH A CARB (IMHO most can't) you won't be able to tune a bike with EFI. The concepts are exactly the same.
I know this is straying off the DI debate a bit but I'm not sure you can apply that as a hard and fast rule across the board.
To give an example, when Aprilia were running the 500 v-twin at GP's they ran carbs for ages. The bike was very fast, very torquey but had certain "quirks" that were very difficult to iron out. Getting it off the line was one, picking up the throttle from over-run mid-corner was another. These problems as ever were due to the size of carb that had to be run for top end performance which made fuelling at small throttle openings very problematic.
By happy co-incidence at the same time Aprilia were working with Orbital Technology in Australia on the Di-Tec scooter project and they asked them to have a look at the fuelling method of the GP bike. A "standard" EFI system was cobbled together and fitted for GP at Brno and made a difference immediately. I remember talking to Jeremy the following week and he said they made more progress that one weekend than in the entire year up to that. The bike improved constantly for the remainder of the season but unfortunately a decision was made during the winter to scrap the project and run with the ill-fated "cube" MGP bike. Rumours abounded of a back-hander from Honda as the Aprilia decision left Roberts as the only ones still flying the 2-stroke 500 flag which meant he was easily out-numbered and the 2-stroke killed off completely from the now newly named MGP class.
Incidently, many people thought the bike was running DI as it had Orbital stickers on it, but that was not the case, it was simply injectors replacing carbs.
EFI gets a raw deal because it many cases it is used where it's not needed therefore brings only added complication with no benefit. But I don't think that's a justification for dismissing it totally out of hand.
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What carb was Aprilia using? Just curious.
I have learned over the years that factory people are no different than the rest of us. They have their way of doing things. They don't always use what's available because it's out of their comfort zone, even in high $$$$$$$$$ racing.
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Dell Orto took care of the carburation and pretty much made anything necessary to try to get the bike to run perfectly.
So they didn't have people jetting the bike, they had a carb manufacturer jetting the bike!
I should also add that a few weeks after Brno, Jeremy set pole position at Philip Island by the biggest margin that season and would probably have won the race if the tyre hadn't disintegrated, again running EFI.
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I know this is straying off the DI debate a bit but I'm not sure you can apply that as a hard and fast rule across the board.
I don't care if you stray off, the info you gave was awesome.
Back in 1993, there was a certain NSR500 with EFI. Shinichi Itoh rode it, and Doohan said he wasn't a R&D rider, he was racing to win. Well it first debuted in the Japanese GP, Wayne Rainey said the bike sounded like a cruise missle coming up and going buy. He also said his YZR500 was being pulled towards Itoh's bike when he was coming from behind him, and then he would rocket by and Wayne would try to get behind him to draft. 9 out if 10 times Rainey couldn't draft Itoh because the bike was fast and would gain about 7 bike lengths. But after the end of 1993 Honda pulled the plug on EFI, not because it didn't work but because of Mick Doohan who wasn't into testing new stuff. Also the NSR 500 of Itao was the first to break 200 mph at Hokenhiem. Funny stuff ain't it?
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Funny stuff ain't it?
Y'know it really hacks me off the way HRC use/abuse (delete according to viewpoint!) the two-stroke engine principle in a way that just suits them. Yes we know the bottom line is that they are sworn against it and you could probably live with that if they'd continually plowed a 4-stroke furrow against the stokers at all levels no matter what.
But the cynical way in which they've used the design to win titles which they then brag about while doing everything in their power to kill it off really tugs my chain. I suppose the final insult was this year when they managed to win the final ever 250cc world championship while ensuring that they're also going to be sole engine supplier for this "conceived in the bowls of hell" 600cc class that's replacing it.
I suppose the only consolation is that Yamaha are giving them a good kicking in just about every other class of racing but that's not much benefit to our beloved 2-strokes!
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I hear ya on that Honda subject MMS, I'm anti-Honda so bad I wish the company as a whole would go down to....well you know where. And it also ticks me off how they treat factory riders like low life scums and if they suck for one race there trying to get rid of that rider instead of fixing the problem, like the bike. Remember the RC211V and the clutch problems. Then to top it they go out and kill every two stroke class by winning the last championship of that class. Except a few like AMA F1 which Yamaha won in 1984 with KR. :P
I think Yamaha and KTM has no reason to remove 2 strokes from there line up. Why? Because they corner the market in these bikes and there selling like hot cakes. ;D They cant justify removing a line up just because every other Jap manufacturer did. Yamaha is playing smart and took their customers from them, so it works out for Yamaha. Now they just need to build a brand new bike for 2011!! :D
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I think the question of Carb or FI is easy to answer.
Flying_lawnmower.wmv
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Helmut, could you please post another link? That one does not work!
Thank you. :D
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Helmut, could you please post another link? That one does not work!
Thank you. :D
Hmmm,dont know why it wont work.Works for me.??? :(
Maybe highlight it and ....??????
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One thing that doesn't seem to get discussed much in DFI threads is volumetric efficiency. A DFI engine can make substantially more power than an identical EFI or carbureted engine, because of greater volumetric efficiency. The fresh air being drawn into the DFI engine is ALL air, there is no fuel to displace any of the air. So the engine is capable of drawing in more air with no other changes than simply switching to DFI.
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I know this is straying off the DI debate a bit but I'm not sure you can apply that as a hard and fast rule across the board.
I don't care if you stray off, the info you gave was awesome.
Back in 1993, there was a certain NSR500 with EFI. Shinichi Itoh rode it, and Doohan said he wasn't a R&D rider, he was racing to win. Well it first debuted in the Japanese GP, Wayne Rainey said the bike sounded like a cruise missle coming up and going buy. He also said his YZR500 was being pulled towards Itoh's bike when he was coming from behind him, and then he would rocket by and Wayne would try to get behind him to draft. 9 out if 10 times Rainey couldn't draft Itoh because the bike was fast and would gain about 7 bike lengths. But after the end of 1993 Honda pulled the plug on EFI, not because it didn't work but because of Mick Doohan who wasn't into testing new stuff. Also the NSR 500 of Itao was the first to break 200 mph at Hokenhiem. Funny stuff ain't it?
The problem with open loop fuel injection on a race engine is the hot/cold pipe dynamic in the engine. Worked OK at Hockenheim and Suzuka but never worked when mid range part throttle fueling was of importance.
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One thing that doesn't seem to get discussed much in DFI threads is volumetric efficiency. A DFI engine can make substantially more power than an identical EFI or carbureted engine, because of greater volumetric efficiency. The fresh air being drawn into the DFI engine is ALL air, there is no fuel to displace any of the air. So the engine is capable of drawing in more air with no other changes than simply switching to DFI.
Very true, hadn't thought about it that way. Plus, each drop of fuel is undiluted by oil. pure air + pure fuel!
Also, i was looking at the bore/stroke ratio of the e-tec direct injected marine engines and was blown away by the piston dimensions. For instance, on one of their engines which has 432cc cylinders, it has a 91mm x 66mm bore/stroke. Hugely oversquare = high revving screamer! can't recall a 2 stroke ever being this oversquare
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Your still going to get a little bit of oil in the combustion chamber no matter what. Why? Because if the main bearings are oiled through lets say the gearbox oil (Bimota V-Due) all that's left is the rod bearings which aren't going to need a lot of oil. But you can now run oil ratios like a RX-7 wankel engine which are like in the 1000 range, maybe not that drastic but you get the point.
In the end, is the engine going to be cleaner? Yes. Is it going to be more efficient? Yes. Will it need less oil to run? That's a positive. Is it going to make more power? Now that depends. No one will know with out R&D, because you just can't assume these days, you need facts to back it up. To be honest I think a DI engine will work for motorcycles we just need someone to build the damn thing. ;D