Another New ICE: The Scuderi Split-Cycle Engine.

[Einhander Sn0m4n]

Firing after TDC?!

By Dan Orzech| Also by this reporter
02:00 AM Aug, 28, 2006

If your next car gets twice the gas mileage of your current vehicle, and belches out only a fraction of the pollution, you may have Carmelo Scuderi to thank.

Scuderi, a Massachusetts engineer and inventor, started tinkering with the fundamentals of the internal combustion engine when he retired in the mid-1990s. The result was a radical new design that could make engines for anything from gas-powered lawn mowers to diesel locomotives lighter, far more efficient, and a whole lot easier on the environment.

Scuderi died in 2002, shortly after patenting the basic concept for his engine. Since then, his children have made it their mission to bring the engine to market. Five of them now work full time for the family startup, the Scuderi Group.

Scuderi began by splitting the heart of the internal combustion engine -- the chamber where air is compressed, mixed with fuel and then ignited -- into two separate cylinders, linked by a passage. Air is compressed in the first cylinder, and then shot through the passage into the second cylinder, where it mixes with the gas and burns.
Click below to see the Scuderi Group's explanation of how it works:

Youtube Video: Engine

The general idea of a split-cycle engine has been around for a century, but none have ever matched the efficiency of traditional engines. Scuderi believed he could solve the problem by pumping highly pressurized air from the compression cylinder into the combustion chamber, and then allowing the fuel and air to ignite when the head of the piston was already moving away from the top of the combustion cylinder.

The method was counterintuitive, because it creates a condition known as firing after top dead center, considered a cardinal sin in engine design since at least the days of Henry Ford.

"In a normal engine, firing after top dead center doesn't work, because the piston will outrun the flame, so you can't build up any pressure," says Scuderi's son, Sal. In the Scuderi engine, however, the combination of highly pressurized air and firing after top dead center creates a highly turbulent environment where the fuel and air ignite explosively, producing far more power than conventional engines.

So far, the engine exists only as a computer model. Two real-life prototypes -- one diesel and one gasoline -- are under construction at the Southwest Research Institute, an engineering research lab in Texas, and are due out next year.

While it is possible that engineering problems may yet emerge, those involved in the project believe the prototypes will work as planned. Computer-generated models are universally used in the automotive industry to design new engines and other parts, and are considered extremely accurate in predicting performance.

Those models show the combustion in a Scuderi engine will be not only more powerful than conventional engines; it will also, surprisingly, be cooler. That means it will spew out far fewer pollutants than today's engines do.

The Scuderi engine could even boost mileage by recapturing energy normally lost during braking, as do hybrid cars. "Unlike current electric hybrids which store the energy in a battery, we are able to store energy in the form of compressed air," says Sal Scuderi. That can be done by simply adding a small air-storage tank, which costs far less than the generators and banks of batteries gas-electric hybrids need.

While working models of the Scuderi engine won't see the light of day until next year, the radical design is already attracting a lot of attention in the automotive world. The company is in talks with big automakers, and when it showed off the new engine at a major automotive-engineering conference in Detroit earlier this year, the Scuderi booth was mobbed.





Interesting how these nice ideas for combustion engines are coming out of the woodwork...

[Mr Bean]

Fixed your link, I heard about them on NPR already. The show there was of course mixed 50% BRILLANT! Hire them! and 50% Crazys! it'll never work!

Which of course was moronic, if they already had plans to build it, why not just sit back and see if it works dumbass?(Or at least that's what I thought when they got some Engineer in there claming that the computer models were flawed and the thing would never work.)

[CaptainChewbacca]

I'll wait and see, but I'm a hopeless optimist for this sort of thing.

[drachefly]

I thought that combustion already consumed most of the fuel (even if it is far less than 100% efficient). Hmm. Maybe if most of the fuel consumed in real cars is consumed uselessly after the BANG part of the cycle, then this could help substantially.

As for realism? Hey, at least they're not claiming over-unity. That's a plus.

[aerius]

I read about this one in one of the major car magazines in the last few months, looks promising but we'll see. I'm pretty optimistic that it'll work but getting it put into production is a whole different matter.

I thought that combustion already consumed most of the fuel (even if it is far less than 100% efficient). Hmm. Maybe if most of the fuel consumed in real cars is consumed uselessly after the BANG part of the cycle, then this could help substantially.

The fuel is almost 100% consumed, but the engine can only harness about 25% of the energy released by the combustion process. It has something to do with thermodynamics, fluid dynamics, friction, mechanical constraints, and lots of fancy math which I don't know of and wouldn't understand anyway, but the end result is that about 3/4 of the energy released by combusting gasoline in an Otto-cycle engine gets wasted as heat.

This engine gets around some of the mechanical constraints & flow issues in a conventional engine which allows it to work more efficiently.

[drachefly]

Yeah, I covered the Otto cycle in my stat mech class. This is still the Otto cycle!

So, if it's better, it had better be just improving something within the class of Otto engines.

[General Trelane (Retired)]

I, too, will wait and see what becomes of the prototypes. At least they're building them.

One weakness--having two cylinders per stage will result in added weight, so while it may be more thermodynamically efficient, what will be its net power to weight?

[Seggybop]

Considering total vehicle weight, I don't think it'd make much difference. Or am I missing something?

[General Trelane (Retired)]

Considering total vehicle weight, it may not seem like much. . .but current develop of ICEs try to shave off every unnecessary ounce. That's partly driven by economics (don't pay for material you don't need) but also by performance.

If the resulting split-cycle engine is 20 pounds heavier than a similar conventional ICE, I expect that to be a problem. How much of a problem depends on just how much more efficient the split-cycle engine is. Considering that a major design goal for high-efficiency vehicles is the reduction on total vehicle weight, even a small additional weight from the engine needs justification.

Then there's also size--this split-cycle engine will likely be larger than a comparable 'conventional' ICE, so power density (power-to-volume ratio) is another point of comparison because in reducing vehicle weight, space is at a premium.