Talk:Split-cycle engine

This article was nominated for deletion on March 31 2007. The result of the discussion was keep, conditional.

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The captive pulse engine is a proposed engine design and is not a split cycle design. The split cycle engine is an existing engine design that dates back to the 1890s per the story that is linked from this page. I suggest that you create a new page called the "Captive Pulse Engine" and categorize it as a "proposed engine design." [[[User:Tallik|Tallik]] (talk) 22:11, 10 October 2008 (UTC)][reply]

The captive pulse article, or at least the present one, was placed by an assistant. I'm actually glad to see it.I constanly recieve inquiries as to the specifics of this type of engine. I hope not too much confusion has been caused by its placement.

I will provide a much better description as soon as i have time to do so.

...For the time being, let me clear up a few things.

1; A supercharger is differentiated considerably from a blower. No blowers have been alluded to within the present description. A blower is a constant pressure pump. A supercharger is not only a constant volume pump, but it must provide sub-pre compression air to constitute an actual supercharged engine. this is done with positive displacement and does not allude to scavenging, as provided for in Clerk type engines. An origional Clerk type engine might be mistaken to be supercharged, but the exhaust and inlet valves open together at obout maximum displacement volume as the pump is just beginning to lower its displacement volume....a scavenging/blower funtion...not supercharging.

2;Scuderi claims to have use a positive displacement pump as the main element to raise pre compression...This is not supercharging...It seems like a misconception of a detuned two-stroke captive pulse engine from the third generation of the engine line...The engine they propose is nearly indescernable from Clerk's original engine....except for the elements approaching captive pulse...The big difference is Clerk and myself have invented and built engines...Scuderi spends more on a website than an engine cost, and it's obvious they have no genius....even if they did, it would be too little....they'd need a supergenius to keep from getting smoked flat-out...Homie don't play

3; As for explosion efficiency, it's evident that it is impossible to exceed 50% using only the expansive force of combustion....a constant stroke captive pulse machine also takes advantage of collapsing gases (etc.),,,,like i said, Homie don't play....such engines are still operating...they were operating when Scuderi filed their first patent....go figure

...well, i'm out of time....

...i'll be back,,,,and i'll try to hurry with an acceptable article

...thank you for your time

T.A. Graves

The captive pulse section is totally unreferenced and I can't find any google references to it. The description is pretty much meaningless. Greg Locock (talk) 10:22, 19 January 2008 (UTC)[reply]

Can I suggest a format for the Captive pulse sub article? It needs

Introduction - a short paragraph describing what it is and why it is notable

Overview, a more detailed description of the design and its history

Design features- specific features of interest

Claimed performance

History (optional)

At the moment it seems to be a random collection of factoids, from which it is impossible to tell how the engine works or whether it has even run. The patent does not appear on a google search. Oh, and is it a split cycle engine? If not then it needs a separate article. Greg Locock (talk) 21:50, 19 January 2008 (UTC)[reply]

...i agree for the most part....yes split cycle as defined by scuderi co. is in fact a feint copy of captive pulse....or captive pulse has been construed as split-cycle.....several hundered variations have been operated (BY GRAVES AND CO)(SCUDERI,,,?),,,,time allowing it, the article will be brought within acceptable perimeters....a seperate article is being prepared for both captive pulse and reciprocating supercharger also..... —Preceding unsigned comment added by Angel of abyss (talk • contribs) 23:11, 19 January 2008 (UTC)[reply]

I could not find any specifics on how the air-hybrid capability would function, beyond that the compression cylinder would be used to fill the air tank. I extrapolated based on my understanding of how an air-hybrid vehicle works...--ryos

The last page of this pdf shows some details of the air-hybrid system.

Thanks for that; I've updated the section to reflect this information.--ryos 04:44, 11 July 2006 (UTC)[reply]

While we're not supposed to cover future products without prototypes, this is an engine design concept, and it ought to be covered on that merit even if a prototype is never produced.--ryos

FYI, gasoline and diesel prototypes are scheduled to be completed in 2007.

That would be a good thing to add to the article. Do you have a source for it?--ryos 04:44, 11 July 2006 (UTC)[reply]

I have a source for at least one of the two engine prototypes. It's good that you asked because I may have jumped the gun, evidence wise. See the last paragraph of this blog entry. I will provide a link to info on the second prototype if one becomes available.

I am a newbie as far as contributions go, but I was wondering how to find out why this page was removed? User:Heritage88 04:44, 11 July 2006 (UTC)[reply]

This article is basically a repetition of the claims made by those who are trying to market the engine concept, right down to the supposedly easily solved "drawbacks." One fairly obvious drawback which is never discussed is the fact that the layout is essentially a very narrow-angle V engine. This has a lot of noise, vibration and harshness (NVH) implications that would require some kind of second-order remediation such as a balance shaft. (It basically would have all the balance problems of a Volkswagen VR6, and it's unclear to me how Scuderi would solve them any more expediently than VW did.) These NVH issues would be doubly true if, as the Scuderi organization suggests may be optimal, the compression and power cylinders were of different sizes. The parasitic losses of such a balance shaft arrangement, which would be required to make the engine marketable in an automotive application, are obviously not accounted for in the efficiency claims or "computer modeled" design, because no equipment to solve these problems is discussed or shown in any of the drawings.

Similarly, there are a myriad of options for increasing efficiency of existing engine designs, many of which are not commonly used because of prohibitive manufacturing costs. From what I can tell, this engine doubles manufacturing costs by doubling the number of cylinders and pistons required. To make a fair comparison, this engine should be compared with engines of similar (i.e. high) cost. This would imply a more efficent engine than the presumably non-turbocharged, non-Miller cycle, non-supercharged, non-direct injected power unit that Scuderi must be using as a baseline. VW's productionization of a gasoline engine that is both turbocharged and supercharged and approaches the efficiency of a diesel comes to mind as a very expensive, highly efficient powerplant that may be comparable...and is not a concept, but an engine sold on the European market today. Mazda's marketing of Miller cycle engines, abandoned due to excessive costs for the efficiency gains measured, is another example of the cost/benefit tradeoff.

Finally, in automotive applications, the doubling of cylinders would have significant negative effects on packaging and total efficiency as installed.

It strikes me that an engine concept that simultaneously is claimed to be simple and based on existing technology yet has no running prototype should be approached with a great degree of skepticism. Simply repeating the developers' own recitation of minor problems is not a true criticism. I am not a mechanical engineer; I am only an automotive enthusiast. I would appreciate a truly qualified person adding some thoughts to this article about the problems with this concept, because some obvious issues not discussed leap out at me and I am hardly an expert. Surely there is somebody at Detroit Diesel or GM Powertrain who could poke some holes in this utopian story with a 10 minute review.

You hit multiple points. I will speak to one or two now and hopefully get to others later. The biggest issue I have is the premise that the engine doubles the number of cylinders and therefore a host problems result. Why does a split cylinder configuration with a compression cylinder and a power cylinder imply that number of cylinders gets doubled? My understanding (I too am not an automotive engineer) is that the gasoline Scuderi engine should be slightly more expensive to build than a conventional gasoline engine and that the diesel Scuderi is projected to be significantly less expensive than a conventional diesel engine. While in theory most of improved milage is due to the increase efficiency, some is due to the engine being smaller and lighter than current engine, reducing overall weight of the vehicle. I’ll try and get back to some of the other points.--CSvBibra 16:56, 23 November 2006 (UTC)[reply]

This article should be deleted:

1. It is obviously a future product without a prototype; it could certainly be restored when and if a prototype is built. The fact that the people trying to sell the concept insist that a prototype is coming is not the same as a prototype.

2. It can't possibly have a neutral point of view, because all the empirical data about the viability and improved efficiency of the concept comes from the Scuderi Group. The core support for the entire concept per The Scuderi Group itself is a computer model that, according to their site, is inaccessible unless the reader is willing to sign a nondisclosure agreement. See footnote here. How can there be an NPOV analysis of a concept when the data is either not available, or is an interpretation of the data by people trying to sell licenses for the concept? Also, if these data are pulled from a Scuderi Group-developed computer model, could we consider this data (if it were available) to be a reliable source, unless we had access to all particulars of the model?

Meersman 20:52, 27 November 2006 (UTC)[reply]

It seems the only thing the Scuderi Group is effectively selling these days is hype about their unproven split-cycle engine technology! Apparently, they've done a great deal of local marketing since most of the investment dollars received to date come from local, trusting investors. However, it also seems the Scuderi Group is determined to sell the engine concept to the US Government by using questionable Congressional "appropriations" and pork-barrel shortsightedness. Are we, as taxpayers, willing to freely fund the building of prototypes with questionable merit, and where the funded-party contributes nothing upfront financially? Instead of trying to force applications for their engine on the American taxpayer through government funding, the Scuderi Group should start putting their money to better use - by giving it back to those unwary local investors! --24.9.57.18 20:17, 1 December 2006 (UTC) —The preceding unsigned comment was added by 24.9.57.18 (talk • contribs).,[reply]

==

I think it would be most productive to focus on the technology rather than using this promising concept as an opportunity to bash the U.S. government and the Scuderi Group through unsupported, unsigned attacks. There are a number of interesting issues raised on this page that would help to produce a more informative profile of the Air-Hybrid technology. The Air-Hybrid engine certainly merits a profile on Wikipedia based on the extensive coverage it has attracted in mainstream outlets in the U.S. and around the world, including national broadcast outlets and professional engineering publications. These sorts of citations are typically used as method of measuring Wikipedia "worthiness" from my understanding.

Tallik 16:03, 15 December 2006 (UTC)[reply]

I agree that how either the government or investors are convinced to pay for the engine's development is irrelevant to this article. I still maintain we have a future product with no prototype, so the article should go. (The air-hybrid is even worse: we have a phantom enhancement to the phantom engine.) If this article is to stay, questioning the specifics of the design is not an "unsupported" attack.

If you have any links to "professional engineering publications" that have anything to say about this engine, I'd genuinely appreciate some direction; I have searched for these and found none. All the coverage I've encountered has been in the general consumer press rather than anything remotely scholarly.

I'll summarize some outstanding questions, all of which--in deference to your definition of what is appropriate--focus on the technology. I would be interested to see if Scuderi Group, or a third party, has any answers.

Questions

Scuderi Group, and this article, state the Scuderi engine "should have better efficiency (from 33% to 40%) when compared to conventional engines." The direct question here is this: What is a conventional engine, exactly? A pushrod 1.6 from a '76 Chevette? A Nissan VQ? They assert X is greater than Y, but never define Y. So, why should we find the difference between the two to be so "promising?"

Should we assume the Scuderi engine, in total, is always just two cylinders (one compression, one power?) Would a version for a large, rear-drive luxury car just have two (highly vibratory) cylinders the size of a bottle on a typical office water cooler?

Or, are these two-cylinder combos paired in multiples to make, say, six cylinders?

This "how many cylinders" question, if it's answered, then leads to more questions:

Would the (Scuderi v-2,4,6,8,12,16) engine have packaging disadvantages vs. a conventional engine of the same output?

How would the engine be dynamically balanced?

If it's balanced with a conventionally appropriate angle of "v" for the number of cylinders, or a balance shaft within the "v," which would be the standard ways of handling this, how would the resulting longer tube running from the compression cylinder to the power cylinder be handled? (Remember, Scuderi Group already admits this tube/crossover valve is somewhat problematic.)

In the air-hybrid model, the air tank would have to be of substantial size and/or weight. In an automotive application, what size would this have to be to achieve the efficiencies claimed? (This could be described in terms of a ratio of air tank to displacement of the power cylinder.)

The article states: "Manufacturing engines based on this cycle should be easy because the design is compatible with existing engine manufacturing processes." It also states: "It may be necessary to use expensive exotic materials to line the cylinder walls." If we don't know what expensive, exotic materials would be required, how can we know they are compatible with "existing engine manufacturing processes? Meersman 09:17, 18 December 2006 (UTC)[reply]

The Scuderi Group website at http://www.scuderigroup.com has considerable information about how the engine design works and is a good place to start your research. The "News and Events" link brings you to a page with links to dozens of articles, including articles from a number of leading automobile engineering publications. Many of these articles are quite detailed and likely answer most if not all of your questions.

Since the Scuderi Engine 1) has garnered worldwide interest from major consumer and industry media and 2) won patent protection in markets around the world, including the U.S., Japan, China, and Taiwan (http://www.scuderigroup.com/patent/patent_portfolio.html) and 3) promises to be the first significant improvement to the combustion engine in nearly a century -- I think it's extremely difficult if not impossible to make the case that it doesn't belong in Wikipedia.

http://www.scuderigroup.com/news_and_events/news_articles.html

Here are links to some engineering and speciality pubs:

Automotive Design and Production: http://www.autofieldguide.com/articles/wip/0506wip01.html

Engine Technology International: http://www.scuderigroup.com/news_and_events/pdf/Engine_Technology_0906.pdf

The Engineer Online: http://www.e4engineering.com/Articles/295801/Driving%20on%20air.htm

Ward's Automotive: http://wardsauto.com/ar/scuderi_air_hybrid/

European Auto Design: http://www.scuderigroup.com/news_and_events/pdf/Scuderi_EuroAutoDesign_7_6_06.pdf

MotorTrend: http://www.motortrend.com/features/editorial/112_0606_technologue_hybrid_qa/index.html

The website is at http://www.scuderigroup.com.

Tallik 14:46, 9 January 2007 (UTC)[reply]

I just read all of your links. Posting links to Scuderi's PR tearsheets doesn't answer any of the questions posted here by myself and others, especially the issues of NVH and what alloys would be required to make this run and survive a decent durablity cycle. Nothing there is an analysis of the concept; it's all "Scuderi thinks..." Most of the criticism in those articles is either fake criticsm from Scuderi or their vendors, or discusses the difficulty of achieving mass OEM productionization on a licensing basis. That's not the point; the concept has flaws that can't be explained away. GM's potential resistance isn't the primary problem.

We still have that bizarre bifurcation: the assertion that it's simple and easy to manufacture, along with no prototype. What's the problem? NVH and materials, maybe?

In response to your specific points above: 1. widespread "interest" means Scuderi has an effective PR machine. I've never questioned that. 2. Patent trolling proves zero. And, 3. "it promises to be the first significant improvement to the combustion engine in nearly a century." All this "promise," just like the links above, ultimately comes back to unverifiable claims made by Scuderi Group. The fact that the article is totally Scuderi POV with no remotely knowledgable and critical response is the issue. I am starting to conclude that this is because, like the fabled 100 mpg carb, the concept is so flawed that actual experts in the field find it unworthy of comment. Therefore, NPOV may ultimately be impossible, because the only people who care enough to comment either way are already Scuderi believers.Meersman 19:42, 28 January 2007 (UTC)[reply]

The Scuderi Group points out on their own website there are over 700 engine builders worldwide. Doesn't it seem peculiar with all the publicity associated with this technology that not one of those "seasoned" companies are responding? There is a call for an expert in automotive engineering to add input to this discussion. I say that there has been "expert" input simply by the lack of excitement or even the slightest bit of interest and input from any of those engine builders who know what is good or bad for their own business and field of technology! Anyone crying conspiracy in the matter will have a hard case to prove. If breakthrough technology is available, then companies will compete for it to get a one-up on their competitors. That's the way the real world of business is! The references cited to justify the Scuderi engine are definitely reputable, but they border on the line of wishful thinking and the authors of those articles clearly and wisely limit their analyses to what they know. Guy Negre has technology similar to the Scuderi Engine and he is an engine builder and businessman with many years of experience. Furthermore, Negre is doing something with his technology and not simply sitting back waiting for someone else to do it for him! So, I believe if there is to be something written about split-cycle engines, then Guy Negre should be given much of the credit. Furthermore, the fact that the Scuderi Group has a host of very similar patents and applications worldwide merely indicates they are no better than a universal "troll" waiting to pounce on anyone willing enough to venture (and actually do something) with any technology remotely similar to theirs. In any case, the Scuderi engine should be featured only as part of discussion forums and should not be given the scientific credibility to be featured as factual until actual prototypes are provided for a thorough analysis, not by us, but by the people who make it their living: the engine builders! CornPops 15:48, 14 January 2007 (UTC)[reply]

In the diagram:

1. Wouldn't we need a water jacket between the compression and power cylinder if the power cylinder were to be as unprecedentedly hot as Scuderi admits it would have to be? The diagram looks like the two cylinders are siamesed. And, therefore, wouldn't that already problematic crossover tube have to be longer to accomodate?

Does their amazing computer model account for this? Who knows? We can't see the model until we sign a confidentiality agreement, and if we do we can't criticize it publicly.

2. Is the compression cylinder marginally larger than the power cylinder? This further complicates the dynamic balance question of how this 12-degree V-whatever wouldn't shake itself apart.Meersman 19:56, 28 January 2007 (UTC)[reply]

I hit the wrong button when I reverted, I think that the edits were in good faith, but seemed a bit random and out of place to me. Sorry if I hit some real stuff in there. LeeG 19:52, 31 March 2007 (UTC)[reply]

I'm a Mechanical Engineer, although my specialty is in energy systems and fluids, not in engine design. I didn't hear about this technology until this morning, but I'll weigh in on this discussion.

First of all, this technology intrigues me more than any hydrogen/biodiesel/plug-in hybrid talked about so often. I don't see any of the pitfalls that typically accompany new, exotic engine technologies. It takes Ford years just to design a new F-150, so Scuderi taking time on a prototype for a completely new engine doesn't rule out them having a good idea. Even Toyota's hybrid "Synergy" drive train originated from an ASME conceptual paper in the 1970s.

Also, many criticisms have at least been answered by Scuderi. The engine will NOT require double the cylinders for the same output, again as modeled by Scuderi. The two cylinders move nearly in unison, with the cylinders either in both inlet and power, or in both compression and exhaust. So, a power cycle would happen twice as often with half the cylinders.

The first problem I see is the higher sustained temperature in the power cylinder. Typical ICEs don't need much treatment for heat as combustion only occurs one fourth of the cycle. By contrast, turbines in power plants must handle combustion temperatures constantly and thus some of the more efficient turbines must use expensive refractory metals. One Scuderi article mentioned using ceramics for the high temperature cylinder, making manufacturing somewhat more expensive.

The second problem is lubricating the power cycle cylinder. Regular engine oil's viscosity is highly dependent on temperature and it could never survive in this engine's hot cylinder. I'm sure lubricants are out there that could handle the temperature, but I'm not sure how expensive they are.

The complex valve system will also be a problem. The Automotive Engineering article seems to say they're moving towards a complex camless design with variable valves, which definitely won't be easy. However, using a pressurized air tank to store energy isn't anything new. If the valves can be taken care of, air hybrid technology will make much more sense than any four thousand dollar battery on the horizon.

Scuderi also said WRT balancing that they will use conventional crankshaft counterweights to balance the engine. Vibrations could definitely be an issue, but vibrations and dampening systems are not my specialty. The place to look on that would be any split-engine prototypes ever made in the past.

Whether it should stay an article, I'm not sure. It's definitely an intriguing idea and probably worthy of an article just about the idea. However, putting it in the same category as Carnot, Diesel, Rankine and Otto is a bit premature. —The preceding unsigned comment was added by 69.180.22.231 (talk) 12:16, 4 April 2007 (UTC).[reply]

A note on cylinder temperature. I don't see why the power cylinder of a split cycle engine should get any hotter than that of a two-stroke engine. Biscuittin 15:11, 11 September 2007 (UTC)[reply]

Although the peak temps should be reduced (firing after top-dead-center accomplishes this), firing every stroke will raise the average temps by reducing the ime to cool between ignitions. —Preceding unsigned comment added by 71.164.100.237 (talk) 18:46, 12 February 2009 (UTC)[reply]

Anyone know where that nifty little animated .gif of a split-cycle engine went?--Lostcause365 03:24, 4 May 2007 (UTC)[reply]

That would be Image:Scuderi Split Cycle Engine - Cycle.gif. Megapixie 03:35, 4 May 2007 (UTC)[reply]

Thanks. Why is it no longer included in the main article?--Lostcause365 04:21, 4 May 2007 (UTC)[reply]

...ok, the captive pulse info needs to be cleaned up....does anybody want to keep all the "dubious and citation needed" tags for any realistic reason...they seem silly....espescially to me, since as an actual witness to the entirety of this machine development i didn't tag anything....i wonder why anyone else would???.....well, i understand to some extent....however, the info is practically sound....or I would have raised hell...

i need arguments for each point of contention... otherwise, i want to pull all those silly denotations... let me know please...Angel of abyss (talk) 00:21, 25 July 2008 (UTC)[reply]

No if you remove the tags without supplying references then I will revert all your changes. Wiki needs references, that is why those tags appear. Presumably Mr Graves will supply adequate documenation when he thinks he wants to, until then, I'm a bit surprised he even wants any mention of the engine, the article as it stands is not good publicity. Greg Locock (talk) 05:07, 25 July 2008 (UTC)[reply]

While the recent edit successfully describes the Twingle,I think you'd be hard pushed to find an RS for the definition of a split cycle engine being used. However if that definition can be sustained by an RS as opposed to self promotional rubbish by fantasists and convicted frauds then I'd agree the twingle doesn't belong here. Perhaps one solution would be a section describing the various forms of piston-supercharged piston engine types.Greglocock (talk) 04:06, 11 April 2015 (UTC)[reply]

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