Dr. James Liao Wins 2010 Presidential Green Chemistry Challenge Academic Award; Second 2010 Green Chemistry Award for Advanced Biofuels
Navistar Delivers eStar All-Electric Trucks to PG&E

Scuderi Split-Cycle Engine Obtaining Better Combustion Consistency Under Low Load When One Crossover Passage Is Shut Off

When operating under low load conditions, the pressure—and ultimately the efficiency—of the Scuderi Engine prototype increases, and becomes more repeatable from cycle to cycle, when one of the two crossover passages is shut off (thereby effectively doubling the pressure in the single open crossover passage), testing by Southwest Research Institute (SwRI) has shown.

The Scuderi Engine is a split-cycle engine that divides the four strokes of the Otto cycle over a paired combination of one compression cylinder and one power cylinder. Intake air is compressed in the compression cylinder and transferred to the power cylinder for combustion. The Scuderi Engine prototype (earlier post) has two crossover (Xovr) passages that connect the two cylinders, which separate the four strokes of the pistons.

Each crossover passage has a crossover compression (XovrC) valve on its upstream end and a crossover expansion (XovrE) valve on its downstream end, which control flow through the crossover passage. In one, cylinder intake and compression occur while combustion and exhaust take place in the other. Fuel is injected in the downstream end of the crossover passages just as the XovrE valve opens. Compressed air then travels at sonic velocity from the XovrE passage to the combustion cylinder, where combustion occurs.

One of the things that was always critical to us was whether or not we would be able to maintain our pressure [at low load]...one of the keys to the Scuderi engine is to maintain high pressure in the crossover passage. We have had several schemes to do that at low loads, low pressure...because we knew that as we went down in load and speed we would be losing pressure in the crossover passages.

—Stephen Scuderi, vice president and patent attorney for Scuderi Group

One concern the Scuderi Group had about the scheme of shutting down one crossover passage at low load was a potential degradation of the mixing of air and fuel, Scuderi said. In fact, he noted, the testing showed that mixing improved with one passage, resulting in a more consistent combustion process.

In tests of the prototype running at near idle load and speed (i.e., less than 2 bar load and 700 rpm) to loads of up to 4 bar and speeds of up to 1600 rpm, shutting down one of the two crossover passages yields a coefficient of variance (COV) as low as 1.4%, according to tests conducted by SwRI.

Typically, a conventional auto engine running on the Otto Cycle will produce COV rates ranging from 2.5 to 4.0%. COV is a measure of the variability between each combustion cycle. Lower COV figures correlate with higher efficiency and more complete combustion. Moreover, the very low COV in the Scuderi Engine indicates that the combustion mix (oxygen and fuel) is even more complete and robust than in a conventional engine.

This makes us very confident that, when fully mapped and analyzed, the efficiency of the engine will be even higher than previously predicted, which so far has been the pattern in the measured data we have acquired to date.

—Stephen Scuderi


Henry Gibson

After years of computer simulations and no prototypes it is a big surprize that such a discovery can be made. Computers simulations are perfect examples of how machines and global warming works.

Computer controlled valve can be built and installed and operated for all engines.

Or perhaps we can see that the Scuderi engine is just a piston version of a jet engine and just go with the Capstone turbines.

If you want a combination of turbine and piston you can go with the Electro-turbine-supercharger of the new OPOC or you could go in the other direction with the Pescara free piston turbine combinations that could burn crude oil without refining like the super large piston ship engines. ..HG..

bill coughlin


It appears you take the time to post a reply without any understanding of this technology. Perhaps, if you "read" the article, you would see that this press release discusses the "tests of the prototype running at near idle load and speed".

Please don't waste anyone's time replying to this post.

Henry Gibson

I was commenting that the many years of computer similations of Scuderi did not reveal the whole truth, and that a prototype should have been built and tested years ago. Scuderi has been long known for relying on simulations rather than tests to keep the investors excited. Please read my prior comment carefully to try and get the irony about computer simulations that was built into it. You can also read my prior posts about Scuderi to find out, fully, that I knew that they were testing now a prototype at long last.

Except for the interesting concept of an air-hybrid version of their engine, the efficiency increases proposed are achieved by plug in hybrids which can use far less gasoline, and turbines are simpler and sufficiently efficient for the low efficiency of traveling at high speeds on motorways.

Wasting energy by traveling at 80 instead of 55, even for long trips, is an issue that will eventually have to be looked at in this world of required energy efficient appliances and water efficient toilets.

If you cannot describe to me, without looking it up, how a Pescara engine worked, please restrain your comments about my understanding of engines. You may also consider what you know about the Still engine used in several ships and stationary engines as well as a locomotive first. ..HG..

bill coughlin

Your disparaging comments towards "Scuderi" appear to have skewed your objectiveness. Sounds like you have been following this years and this has become "personal" for you.
You lack an understanding the new "Scuderi Cycle", the thermodynamics properties that are present in this new technology and the efficiencies gained when the engine is run in the air-hybrid mode.
When you develop a full understanding of these concepts, perhaps you may well be able to provide more insightful comments, instead of bashing.

Roger Pham

Pretty soon, most cars will be HEV's, and the ICE will only run when it's most efficient to do so. This will make this discovery moot. No need to run ICE at low power setting, low efficiency level anymore.

I move that the nation should have plan to retrofit many many existing cars into HEV's, in the wake of the Gulf oil spill disaster.

bill coughlin

You mean to tell me that if your ICE in your HEV could be was 50% more efficient you would not use Scuderi technology.
...your comment.. "This will make this discovery moot"....
You need to do some research on this before you discount it so quickly.


I think Henry understands this "technology" quite well, even amidst the BS that comes from Scuderi.

So now, just like daytime TV they create a problem where none existed and say they solved it and, in fact, the "very low COV in the Scuderi Engine indicates that the combustion mix is even more complete and robust than in a conventional engine."

I will be relieved when all the other auto makers are forced to quit unloading those high COV engine on us.

And then
"This makes us very confident that, when fully mapped and analyzed, the efficiency of the engine will be even higher than previously predicted, which so far has been the pattern in the measured data we have acquired to date."

I guess they mean after another decade of simulation and fund raising.

Roger Pham

Current HEV's using Atkinson-cycle ICE has already demonstrated higher peak efficiency and even higher part-load efficiency than the Otto-cycle ICE that are in conventional non-hybrid vehicles. Scuderi-cycle engine claims 10-15% higher efficiency than Otto-cycle engine in conventional cars, but cannot be more efficient than the Atkinson-cycle engine, the latter is simpler and does not have the losses of moving compressed air through a series of valves and pipes instead of combusting the compressed air directly.

Watch out for HEV's using HCCI combustion in conjunction with high expansion Atkinson cycle, and HEV's with turbocharging Atkinson-cycle engine with electrical turbocompounding for larger vehicles in order to wring out the last BTU's from every drop of fuel.

And after 2015, watch out for FCV's with tank-to-wheel thermal efficiency above 60% that will solve the oil spill and oil pollution problem once for all the coming milleniums.


I don't think the Scuderi concept is really promising for gasoline engines, it is more interesting for diesel because its highly turbulent combustion and injection after TDC reduces NOx and soot, at least if we beleive their claim which they haven't really proved yet...

But any concept of ICE will have hard time to make it through, turbo charged high pressure diesel are already very efficient and powerful. Future will tell but they will have to show really strong benefits to convince cars manufacturers. I think new ICE concept could be successful in emerging countries where marketing has not yet established standards so the market is more open, and hybrid are probably too expensive for India or china.


After having read your often bold statements, pro and con the Scuderi principle, I am curios where you get the information for such assessments. For example, at the home page of Scuderi, I find mostly information adapted to investors, not engineers. There are many patents and patent applications but mostly such information tend to be somewhat misleading and do not fully reveal how the idea will be applied. I have been in the business since mid-1980´s and I think that I could grasp that, at least theoretically, this combustion cycle could have a potential for high efficiency (as many other modifications to the otto and diesel cycles do...). However, when you try to make a practical application, you sometimes have to make compromises that reduce this potential. To be able to better assess the potential of the Scuderi engine in practical applications, I would like to study some technical/scientific publication where the current development status and the routes chosen are clearly stated. Since I have not seen any information of this kind, I come back to my initial question: Where do you find the information to make your assessments?

I can fully understand that Scuderi want to keep some aspects confidential and therefore, they choose to reveal just as much (or little) information as they want, i.e. just enough to keep current investors happy and to attract new investors but not enough for anyone else to get any insight.


ESStor is following Scuderi's foot steps?


The thing I still can't get past is how the Scuderi engine's combustion piston/cylinder will survive constant exposure to high temperatures. Inconel engines anyone?


You mean, "if they ever build a production prototype, will the combustion piston/cylinder will survive constant exposure to high temperatures".

The computer simulation does just fine, I am sure.


Most of the Scuderi comments on this web site have been anti-Scuderi from the same group of naysayers however the Scuderi Group continues to keep the interest of 15 of the top 20 OEM'S. Why so? Do you think the top OEM's executives and engineers would pay them the time of day if there was no real substance in this technology? After licensing agreements are sign and the company goes public will you still have reason to continue to bash the Scuderi Group? Your future credibility is at stake.


Scuderi has no intention of building a full engine, they just want to licence their patents, that means that if an engine or car manufacturer isn't convinced in the first place, this engine will stay as it is : vaporware.

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.


Post a comment

Your Information

(Name is required. Email address will not be displayed with the comment.)