As all of us regulars here have come to see and expect we tend to have a 'New IC engine design of the week" thread running here almost every day so I thought that I would start my own 'New IC engine design of the week' related thread that asks the basic and oh so overlooked questions that never get properly answered or accounted for from the designers of those wacky whimsical contraptions that are supposed to save us from our selves or at least save us from saving our money anyway. 
So for both good fun and proper engineering etiquette here are four basic questions that need to be accurately and plausibly answered before your 'New IC engine design of the week' will get any serious interest other than being just a good laugh for those who actually know something about IC engine design and operation principals. 
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All too often the idea for a 'new and improved' internal combustion engine pops up, usually with very little rational explanation as to the how's and whys, of its supposed improvements or gains over the common IC engines mass produced today. So to be fair here is a basic check list of four things that need to be addressed before anyone of any intelligence or engineering backgrounds will take a new design serious to any great degree. Mostly this need comes from the overwhelming problem faced by the reality that form still follows the intended function and there are a few basic criteria that need to be addressed before anything can be designed.
1. What is the real reasoning behind the new design, cleaner or more efficient?
2. What is the intended application or target market of this new design small public transport or commercial level application?
3. What evidence do you have that supports it being better in any rational way meaning, did you at least do your homework before hand?
4. What gains/losses will the customer/end user see for using such a new engine design?
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The first question can be put as simply as 'Why do you want it more ______' to save fuel/money or some other reason? Although that sounds simple enough here just some of the basic problems behind it. Internal combustion engines can be made far more efficient at turning fuel energy into usable mechanical energy but at some point the design, manufacturing, and operational costs start to outweigh the financial savings gained by using less fuel.
So do you make the system less efficient but save over the long term on operating costs or do you find a cheaper/more cost effective alternative for one or more components related to this problem? Then there is the second major issue with the first question is that there are the inevitable standards that the new design has to meet which means do you save money or fuel by making the energy conversion operate at peak efficiency or do you make it work at a "cleanest burn rate"? Peak engine energy conversion efficiency and peak theoretical combustion cleanliness is not the same thing.
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The second question can be put as simply as 'Who/what is the intended target market and application of this new design?' Although that sounds simple enough again that too has problems simply from the unavoidable fact that not that all applications and working environments are the same and cannot ever be made to be the same. What is the new design intended to be used in, a steady fixed load rate or highly variable operating condition?
A steady continuous load does not require large changes in speed or overall working conditions so in that application it can be designed to work near an optimum efficiency level simply do to that type of application having a small range of expected working conditions. However in a different application, such as a commuter vehicle that deals with widely varying working speeds and environmental conditions, the design has to be made far different or else some secondary method of leveling out the highly variable work load needs to be implemented which will add further complexity and costs to be able to work in that type of application. A freight train and a taxi cab are too very different working environments.
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The third question relates to hard evidence based on real science and understandings of how things really actually truly work. That is if you did not do your homework and thusly cannot provide a solid proven base for the new designs supposed gains over previous and similar concepts it's probably going to be dead before the first one ever gets built.
To get anyone interested the new design it needs at least some level of hard proven in the field test data to back up the purported claims behind it. That in itself implies that 'Theory theory theory and pretty lines on paper blah blah blah' doesn't mean a thing to anyone else if the new design won't actually do what it's supposed to do when built out of the available materials of today's levels of technology. So unfortunately once again if it relies on some mystery component or material that does not yet exist then it cannot be built or work exactly as proposed.
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The fourth question has as much to do with personal views and politics as it does real science and practical application in the real world. What standards or needs will the new design cater to the most? Is it intended to be the most efficient and cheapest power source so that the user saves money by not paying for more fuel than needed or does it favor questionable political agendas that do not necessarily have the best interests of anyone or anything other than themselves in mind?
Internal combustion engine efficiency for vehicles can and at one time did run at considerably more efficient fuel consumption to mechanical conversion efficiency rates than they do now. Unfortunately, largely to clueless halfwits in politics and environmental organizations, rules and demands on how 'clean' the exhaust is over how little fuel is used to do useful work became more important than how much money goes out of you and everyone else's pockets. So what standards and to whom does this new design favor?
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We all like to hear about a new concept or idea but being left with unanswered questions or flat out no real answers at all never brings out a good or favorable view of the person who proposed it.
Good Answers: