Saw a link to this outfit on Autoblog: http://www.scuderigroup.com/technology/the_technology.html Look at the animations particularly---make your brain itch. What the thing amounts to is essentially a 2-stroke engine with built in supercharging. More I think about the idea the more sense it makes. Whether their claims of substantially increased efficiency and reduced NOx output pan out remains to be seen but according to Autoblog they just got a grant from the Department of Defense to develop the design.
I see multiple reasons why it won't work as well as claimed, probably worse than a convential engine. the prrof will be in the pudding for me. http://www.scuderigroup.com/technology/animations/split_sideview.html Can you name two reasons this won't work as well as a conventional engine?
I think the pumping and friction losses would offset the power gains. Not to mention the engine would be overly heavy. Looking from here, a blown engine, turbo or mechanically blown could do as well. Interesting too that they don't seem to have a working model of the engine. Theory and cartoons are interesting, but it looks more like an investment scam than anything else. Build the engine, get it on a dyno and then we'll see how it does. Until then....
mee too, i'm no engineer, and without me going on and struggling to find the words to explain, i just don't think it will work. it's kinda hard too, to critique their theory, when they just give you the very basics, hope they have it thought out a lot more than the animations!i guess they can prove me wrong and build a prototype! you'd have to have some incredible gains in efficiency and power to justify the increased complexity
I like the magical poppet in the first stage's cylinder - they don't show how that is operated. Also I would think they're overlooking the fuel washdown and puddling problems of a cold non-firing cylinder then p***ing it to the firing cylinder. I would think the fuel would be better off injected by the secondary intake valve, but then it's just another forced induction engine - and a turbo would probably outperform it due to less frictional losses...
Most new engine technology is developed with motorcycles first... In the case of the split-single design, an eastern European engineer working with DKW developed this configuration (or a variation of it, actually) prior to WWII to increase the output of two stroke motors. I want to say the engineer's name was Janicek, but that doesn't sound quite right. Someone already hit the nail on the head - the configuration's frictional losses offset the majority of the HP gains. Actual HP gains were modest at best. The config used by DKW relied on a large diameter, short-stroke 'displacer' piston to compress the intake charge, and the design was indeed raced in the late 30's. Yeah - it's a method to separate the undeducated Barrett-Jackson folks from their capital.
There was an early American car with I think big 2-stroke cold cylinders used to supercharge 2 each regular smaller power producing 4 stroke cylinders. Name is gone from my head--Bluto, Fur Biscuit, and '37 Kid probably drive them to work, though. Hard to move enough air, pumping cylinder is just as inefficient as the power cylinders when engine is off its torque curve as well as friction...seems to me pumping cylinders would need to be BIG, and would need to be run at variable speed DIFFERENT than power cylinders, have variable valve timing to broaden best filling range... But I'll buy one of them there magical poppets--that'll be dynamite in a flathead.
im by FAR not a motor guy, but at the moment im learning all i can whle rebuilding my motorcycle motor... id say it would be like a motorcycle (say a vtwin) running on 1 cylinder which if ya ever fouled a plug, it ****s..... the flow of air from 1 cyl to the other i would ***UME would NOT provide more power than a conventional engine. think about it, for this motor, you need to run at more than DOUBLE the power of a dare i say "conventional" motor. a ya got crank weight, etc. etc.
in the motorcycle world this type of engine is known as the "twingle" i think you could buy Sears Allstate bikes built by DKW or Puch Or Zundapp,i can't remember which...
Was a puch twingle. twingles had a shared combustion chamber; they were single-stage in their compression. The DKW motor had a separate 1st stage displacer piston. I'll try to dig up a ref on the web...
I'm not findin' much tech info, but here's a pic of the bike. Won world championships in '38 and '39. Featured damned near the EXACT same architecture as the motor in the thread - the displacer piston can be seen on the front of the motor; the two pistons were in parallel longitudinally and the head is the silvery thingie on top of the motor. All that is old is new once again...
I'm not entirely sure why you'd need the compression side to be wildly bigger than the combustion side for good power. It'd need to be rather bigger to get a supercharging effect but it doesn't seem like a severe limiitation in a fresh design. Additionally as they point out each side can be optimized for its job. The compression side can be built with lighter components since it wouldn't have to endure combustion pounding. Fuel washing in the "cold" intake cylinder shouldn't be a big problem since high efficiency direct injection could be used. Cold is a relative term here. The heat of compression and careful design of the coolant jacketing should help in that regard. Seriously precise timing would be needed in something like this but it should be no sweat for modern engine manangement systems. That "poppet" valve, a check valve actually, might well be the trickiest part of the whole thing. As far as power goes there are the same number of power pulses per revolution as any other 4-stroke engine. The combustion side may be a "2-stroke" setup but it would not suffer from things such as fixed port timing and oil in the fuel. As to why not just bolt a blower on and be done---well beats me but but this particular split cycle design at least attempts to address that question---a**** others. The DoD gave the company over a million bucks to get some hardware built---admittedly not that much these days. Guess we'll see what they do with it. The whole thing being a scam is a distinct possibility.
Darwin - the advantage of a big displacer piston is the piston's only job is compression - which means it's no longer limited to attempting the balance between long stroke (torque) and short stroke (revs). If all the displacer has to do is compress the charge, then it can have a REALLY short stroke which cuts down on ring speeds, frictional losses, and heat generation. Steam engines on ships used a variation of this - a three-cylinder 'up-and-downer' had a very small primary cylinder, a medium size 2nd stage, and a hu****ous 3rd cylinder. Steam was shuttled from cylinder-to-cylinder, losing pressure with each revolution - the net effect was a similar power output from each cylinder, even tho the final stage had only a few PSI on it. These engines were friggin BIIG, BTW. I stood on a main bearing inna cement freighter circa 1926; the cap had cracked - they repaired it via welding WHILE IT WAS RUNNING!
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