There seems something fishy there.. If you're using the engine to compress it's exhaust there will be more resistance to the exhaust leaving the cylinders and the engine will have to work harder (i.e more fuel/air).. Not that theoretically there aren't times during the functioning of a normal engine that there isn't excess energy produced, but it just doesn't seem like it would be all that fruitful.

i agree about the questionable use of exhaust. that would require a whole redesign of exhaust system. it's possible a small amount of exhaust pressure could somehow be stored in a "trickle charge" way.

the part that seems totally reasonable is using the air pressure from something like engine braking (or j-brake). in theory that is a lot of potential compressed air that's otherwise wasted. engines already compress air/fuel for combustion, so that part of the hardware is in every car already. clever thinking!

i would think capturing this air would also eliminate the noise ordinances against trucks j-braking in some towns/cities?

==== author's response follows ====
Am not able to discern from the site whether exchaust is compressed directly or used to compress pure air instead. It seems plausible that the design includes different valve types as well. Many questions that only will be resolved when a full prototype is tested and shown.

There's nothing fishy here. The compressed air does not come from the exhaust. It comes from the non-firing piston. I would imagine that the compressed air is diverted from the combustion cylinder to the storage tank when there is no power requirement such as during braking. It may also be that some of the compressed air created is used in the combustion process and some is stored in the tank, the ratio of stored air varying with the power requirement. There would be no modification of the exhaust system. This engine could be built using the same hardware that is used in today's engines. Nothing new would have to be invented. No major retooling would be required. That's one of the many attractive features of this technology.
The engine is like a two stroke in that it fires once for every crankshaft revolution unlike a four stroke that fires only once in two crankshaft revolutions. That's one of the reasons that it makes as much or more power than a conventional engine. Yes, it has half the cylinders where combustion occurs but it fires twice as often.
The intake charge is pressurized as in a supercharged engine but it accomplishes it without a supercharger or turbosupercharger. It can also be manufactured as a diesel or a gasoline engine. It achieves lower emissions without the use of a catalytic converter which further reduces its cost and complexity and allows lean air fuel ratios that would not be possible in conventional engines. Since the exhaust has neither a turbosupercharger or a catalytic converter impeding its flow the exhaust would be considerably less restrictive rather than more restrictive. One of the key ways that this engine achieves its efficiency is that it fires after top dead center while the piston is on it's downward stroke, something that can't be done in a conventional engine without seriously degrading it's efficiency.

There is also BMW's turbosteamer, which apparently functions by converting heat from the exhaust and converting it to steam which in turn turns the crankshaft.

It addresses one of the primary areas of energy loss in the modern internal combustion engine, which is heat.

Still hard to visualize. I wish they had an animated diagram showing exactly what's happening with the intake and exhaust air and whatnot.

And idea that has occurred to me before is to use engine braking to store pressurized air in a tank, and then use that to propel the engine until you run out of pressure again. I think the only thing you'd need to do mechanically would be to put the tank in the car and connect it to the intake and exhaust with computerized valves. Then the computer could be made to possibly downshift (on an auto or CVT transmission) during lighter braking and only activating the real brakes when braking hard enough to need them. I'm sure this has been thought of before...

How about using the heat from the exhaust to compress air. I have no idea how it would work, but the loss of energy in the form of heat is one reason why internal combustion engines are so inefficient; if that energy could be used the efficiency could increase dramatically. I'm also curious as to whether the braking system and the air compression system could be combined so that energy lost accelerating and braking could be recovered.

It is my understanding that 2 stroke engines are (at least historically) quite dirty.. And those seem to be very strong claims concerning the benefits of this design. It sounds too good to be true.

George, Do you know something that we don't?
=== author's response follows ====
The truism you mention about "2-strokes" is in regard to the sort where you have to add oil to the gasoline in about a 1/50 ratio, and the oil is partlly combusted, leaving enough residue on the cylinders to lubricate. These oil burning 2-strokes are used in scooters and were once common on lawn equipment. They predominate still in chainsaws and wherever else weight is at a premium. Not needing oil distribution, they are much lighter than ordinary 4 stroke engines. George probably intends the non-oil burning variation.

Incidentally, Saab made a 2 stroke engine automobile (with oil auto injected into fuel) for which it was famous until some time in the 1970.s A real smoke bomb.

This is perhaps an oversimplification and the claims of "revolutionary" are probably overstated as well. According to the description Motortrend gives of the independent analysis, the gains are theoretically there, though incremental, not fundamental.

Using exhaust pressure to precompress combustion gases is after all basically what a turbo charger does.

Recapturing heat loss through steam assist is also an idea that's been around for decades, but the relatively small efficiency gain for the added complexity has not been demanded by consumers at the accompanying price.

Here's a more complete description of the engine cycle. http://www.motortrend.com/features/editorial/112_0606_technologue_hybrid_qa/scuderi.html

So don't get too excited. Theoretical efficiency improvements have been collecting in closets for years. It's only news when someone can make it perform in real world production and business model.

Good luck to them.

When many big trucks slow down you may hear this loud "jack hammer" sound, which is nothing more than compression braking. Basically the intake and exhauast valves are kinda reversed so that the engine and transmission help to slow down the truck by compressing air. Instead of using the expanding gases in an active firing cylinder to move the vehicle, the dead cylinder is used to compress air to help with braking and fuel savings. It sounds like this new hybrid sys just takes the compressed air during braking and stores it in a tank. It can then be used to help propel the truck from a stand still. This is perfect for UPS trucks in a stop and go urban environment.

Sorry that link got cut short. Here's the MotorTrend Article

http://www.scuderigroup.com/technology/animations/index.html

Here is an animation of the Scuderi engine from the Scuderi site.
Three different views are presented, side split view, three quarter view, and side view. Click on any one of the view descriptions to see that view. I think it will help a lot to understand how this engine works.

It is not a two stroke engine. I said in my earlier post that it's "like" a two stroke engine in that it fires once for every crankshaft revolution.

I think it would be more accurately described as a four stroke with the strokes divided between two pistons. Two pistons that do two of the strokes simultaneously allowing the engine to fire every crankshaft revolution instead of every other crankshaft revolution as in a conventional four stroke engine.

The intake and compression strokes occur in the non-firing cylinder. The power and exhaust strokes occur in the firing cylinder.

The compression and exhaust strokes occur simultaneously. The intake and power strokes occur simultaneously.

Here's the twist...the intake stroke is not utilized.
Instead, a fuel injector injects fuel directly into the combustion chamber. It's called direct injection.

There are conventional four stroke engines that have direct injection, i.e. Audi, Volkswagen. I believe the latest Audi A6 was the first car with direct injection.

In carburated or non-direct fuel injected engines the air fuel mixture is DRAWN into the cylinder by the vacuum created by the downward traveling piston. A direct injected engine does not utilized this vacuum. Instead, as I said, a fuel injector INJECTS the fuel into the cylinder.

There have been two stroke engines built that don't mix the oil with the gas and have their lubrication in the crankcase just like a four stroke engine. However, I don't believe that these engines have ever reached mass production in four wheeled vehicles. The beauty of these engines is that they make the same power with half the displacement because they fire once for every crankshaft revolution. They utilize direct fuel injection. If you would like to do more research type "Orbital engine" in your search engine.

I read the Motor Trend article on the Scuderi engine.
A quote from it:
"The basic engine's overall efficiency is estimated at 43 percent (up from about 33 percent for ordinary engines), with a compressed-air hyrbrid system boosting that to over 50 percent."

That means that a Scuderi engine without hybrid technology is 30% [(43-33)/33] more efficient than a conventional engine. Adding hybrid technology boosts it to 51% [(50-33)/33].
The hybrid contribution being 21% (51-30).
In other words, the contribution of the Scuderi technology exceeds the contribution of the hybrid technology.
In other words, a hybrid Scuderi engine whomps a hybrid only engine in efficiency gain by more than double (51% vs 21%).
And...it does this without electrical motors or batteries.
It's energy storage system consists of an air tank. And, of course, we know that what's inside this tank is as light as....air!

=== author's response follows ====
Thanks George. Looking back what I've read, including these great comments, I must say that the Scuderi people could do a better job of explaining themselves to non-engineering people. The recent press releases, especially, do not lay out clearly that two distinct technologies are combined under the Air-Hybrid term.

As someone else mentioned, success will rely on business accumen. "Build-it-and-they-will-come" attitudes never have worked and never will. If they were able to leverage multi-fuel compatibility, a favorable weight/HP, high torque, low cost to mfg, and (fingers crossed) a generally lower emissions profile than all other ICE's on today's market, it would be a killer combo.

The concept of the air engine design is not radically new. Several vehicles have used exhaust gas recycling for many years; carbonization is a significant problem requiring frequent costly service. The idea of increasing compression has also been used for many years in the form of turbo-charged engines to increase oxygen delivery. The real problem that needs to be addressed is the incomplete combustion of the delivered fuel (less than 25%). What is required for complete combustion is delivery of the fuel source into the combustion chamber at optimal temperature in a 100% vapor state, rather than the cold liquid state in which it is currently delivered. Furthermore, the addition of other gases to the hydrocarbon fuels increases their combustibility yielding more rapid and complete release of energy. Finally, recovering energy loss in the form of heat using a heat exchanger (to achieve vapor state and optimal temperature) significantly helps to reduce the current inefficiency of the internal combustion engine and increase it’s power output.

To better understand how this engine works, see this movie:

http://www.youtube.com/watch?v=Kogz4wedwtk

I think you have air-pressure hybrid and Scuderi concepts accidentally mixed together. According to A Wired article: the air pressure used in the specific Scuderi design actually produces twice as much power per gallon of gas -- something about air turbulence; also the ability to fire past top dead center instead of before (the flame wave has to chase the cylinder in the before).
http://www.wired.com/news/technology/autotech/0,71648-0.html?tw=wn_index_25

ON TO OF THAT you get to add the pressure saving hybrid design to get even more efficency (being tested by UPS): a virtual efficiency miracle that may be right around the corner -- or it may not.

Looks a lot like a "CAFEC" engine to me.
http://www.cafecengine.com

I wonder which came first